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Periodic table - Wikipedia
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id="toc-Group_names_and_numbers" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Group_names_and_numbers"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.1</span> <span>Group names and numbers</span> </div> </a> <ul id="toc-Group_names_and_numbers-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Presentation_forms" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Presentation_forms"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.2</span> <span>Presentation forms</span> </div> </a> <ul id="toc-Presentation_forms-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Electron_configurations" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Electron_configurations"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.3</span> <span>Electron configurations</span> </div> </a> <ul id="toc-Electron_configurations-sublist" class="vector-toc-list"> <li id="toc-Order_of_subshell_filling" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Order_of_subshell_filling"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.3.1</span> <span>Order of subshell filling</span> </div> </a> <ul id="toc-Order_of_subshell_filling-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Electron_configuration_table" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Electron_configuration_table"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.4</span> <span>Electron configuration table</span> </div> </a> <ul id="toc-Electron_configuration_table-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Variations" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Variations"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Variations</span> </div> </a> <button aria-controls="toc-Variations-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Variations subsection</span> </button> <ul id="toc-Variations-sublist" class="vector-toc-list"> <li id="toc-Period_1" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Period_1"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.1</span> <span>Period 1</span> </div> </a> <ul id="toc-Period_1-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Group_3" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Group_3"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.2</span> <span>Group 3</span> </div> </a> <ul id="toc-Group_3-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Periodic_trends" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Periodic_trends"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Periodic trends</span> </div> </a> <button aria-controls="toc-Periodic_trends-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Periodic trends subsection</span> </button> <ul id="toc-Periodic_trends-sublist" class="vector-toc-list"> <li id="toc-Atomic_radius" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Atomic_radius"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1</span> <span>Atomic radius</span> </div> </a> <ul id="toc-Atomic_radius-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Ionisation_energy" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Ionisation_energy"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2</span> <span>Ionisation energy</span> </div> </a> <ul id="toc-Ionisation_energy-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Electron_affinity" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Electron_affinity"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.3</span> <span>Electron affinity</span> </div> </a> <ul id="toc-Electron_affinity-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Valence_and_oxidation_states" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Valence_and_oxidation_states"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.4</span> <span>Valence and oxidation states</span> </div> </a> <ul id="toc-Valence_and_oxidation_states-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Electronegativity" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Electronegativity"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.5</span> <span>Electronegativity</span> </div> </a> <ul id="toc-Electronegativity-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Metallicity" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Metallicity"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.6</span> <span>Metallicity</span> </div> </a> <ul id="toc-Metallicity-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Further_manifestations_of_periodicity" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Further_manifestations_of_periodicity"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.7</span> <span>Further manifestations of periodicity</span> </div> </a> <ul id="toc-Further_manifestations_of_periodicity-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Classification_of_elements" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Classification_of_elements"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Classification of elements</span> </div> </a> <ul id="toc-Classification_of_elements-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-History" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#History"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>History</span> </div> </a> <button aria-controls="toc-History-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle History subsection</span> </button> <ul id="toc-History-sublist" class="vector-toc-list"> <li id="toc-Early_history" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Early_history"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.1</span> <span>Early history</span> </div> </a> <ul id="toc-Early_history-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Mendeleev" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Mendeleev"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.2</span> <span>Mendeleev</span> </div> </a> <ul id="toc-Mendeleev-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Atomic_number" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Atomic_number"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.3</span> <span>Atomic number</span> </div> </a> <ul id="toc-Atomic_number-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Electron_shells" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Electron_shells"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.4</span> <span>Electron shells</span> </div> </a> <ul id="toc-Electron_shells-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Synthetic_elements" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Synthetic_elements"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.5</span> <span>Synthetic elements</span> </div> </a> <ul id="toc-Synthetic_elements-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Future_extension_beyond_the_seventh_period" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Future_extension_beyond_the_seventh_period"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>Future extension beyond the seventh period</span> </div> </a> <ul id="toc-Future_extension_beyond_the_seventh_period-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Alternative_periodic_tables" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Alternative_periodic_tables"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>Alternative periodic tables</span> </div> </a> <ul id="toc-Alternative_periodic_tables-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Notes" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Notes"> <div class="vector-toc-text"> <span class="vector-toc-numb">9</span> <span>Notes</span> </div> </a> <ul id="toc-Notes-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">10</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Bibliography" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Bibliography"> <div class="vector-toc-text"> <span class="vector-toc-numb">11</span> <span>Bibliography</span> </div> </a> <ul id="toc-Bibliography-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Further_reading" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Further_reading"> <div class="vector-toc-text"> <span class="vector-toc-numb">12</span> <span>Further reading</span> </div> </a> <ul id="toc-Further_reading-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">13</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Toggle the table of contents</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Periodic table</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 202 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-202" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">202 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-af mw-list-item"><a href="https://af.wikipedia.org/wiki/Periodieke_tabel" title="Periodieke tabel – Afrikaans" lang="af" hreflang="af" data-title="Periodieke tabel" data-language-autonym="Afrikaans" data-language-local-name="Afrikaans" class="interlanguage-link-target"><span>Afrikaans</span></a></li><li class="interlanguage-link interwiki-als mw-list-item"><a href="https://als.wikipedia.org/wiki/Periodensystem" title="Periodensystem – Alemannic" lang="gsw" hreflang="gsw" data-title="Periodensystem" data-language-autonym="Alemannisch" data-language-local-name="Alemannic" class="interlanguage-link-target"><span>Alemannisch</span></a></li><li class="interlanguage-link interwiki-am mw-list-item"><a href="https://am.wikipedia.org/wiki/%E1%8B%A8%E1%8A%95%E1%8C%A5%E1%88%A8_%E1%8A%90%E1%8C%88%E1%88%AE%E1%89%BD_%E1%88%A0%E1%8A%95%E1%8C%A0%E1%88%A8%E1%8B%A5" title="የንጥረ ነገሮች ሠንጠረዥ – Amharic" lang="am" hreflang="am" data-title="የንጥረ ነገሮች ሠንጠረዥ" data-language-autonym="አማርኛ" data-language-local-name="Amharic" class="interlanguage-link-target"><span>አማርኛ</span></a></li><li class="interlanguage-link interwiki-smn mw-list-item"><a href="https://smn.wikipedia.org/wiki/R%C3%A1i%C4%91ul%C3%A2%C5%A1_vu%C3%A1h%C3%A1d%C3%A2h" title="Ráiđulâš vuáhádâh – Inari Sami" lang="smn" hreflang="smn" data-title="Ráiđulâš vuáhádâh" data-language-autonym="Anarâškielâ" data-language-local-name="Inari Sami" class="interlanguage-link-target"><span>Anarâškielâ</span></a></li><li class="interlanguage-link interwiki-anp mw-list-item"><a href="https://anp.wikipedia.org/wiki/%E0%A4%86%E0%A4%B5%E0%A4%B0%E0%A5%8D%E0%A4%A4_%E0%A4%B8%E0%A4%BE%E0%A4%B0%E0%A4%A3%E0%A5%80" title="आवर्त सारणी – Angika" lang="anp" hreflang="anp" data-title="आवर्त सारणी" data-language-autonym="अंगिका" data-language-local-name="Angika" class="interlanguage-link-target"><span>अंगिका</span></a></li><li class="interlanguage-link interwiki-ab mw-list-item"><a href="https://ab.wikipedia.org/wiki/%D0%90%D0%B5%D0%BB%D0%B5%D0%BC%D0%B5%D0%BD%D1%82%D2%9B%D3%99%D0%B0_%D1%80%D0%BF%D0%B5%D1%80%D0%B8%D0%BE%D0%B4%D0%B8%D0%BA%D0%B0%D1%82%D3%99_%D1%81%D0%B8%D1%81%D1%82%D0%B5%D0%BC%D0%B0" title="Аелементқәа рпериодикатә система – Abkhazian" lang="ab" hreflang="ab" data-title="Аелементқәа рпериодикатә система" data-language-autonym="Аԥсшәа" data-language-local-name="Abkhazian" class="interlanguage-link-target"><span>Аԥсшәа</span></a></li><li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%A7%D9%84%D8%AC%D8%AF%D9%88%D9%84_%D8%A7%D9%84%D8%AF%D9%88%D8%B1%D9%8A" title="الجدول الدوري – Arabic" lang="ar" hreflang="ar" data-title="الجدول الدوري" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-an mw-list-item"><a href="https://an.wikipedia.org/wiki/Tabla_periodica_d%27os_elementos" title="Tabla periodica d'os elementos – Aragonese" lang="an" hreflang="an" data-title="Tabla periodica d'os elementos" data-language-autonym="Aragonés" data-language-local-name="Aragonese" class="interlanguage-link-target"><span>Aragonés</span></a></li><li class="interlanguage-link interwiki-roa-rup mw-list-item"><a href="https://roa-rup.wikipedia.org/wiki/Tabela_periodic%C3%A3-a_elements%C3%A3lor" title="Tabela periodicã-a elementsãlor – Aromanian" lang="rup" hreflang="rup" data-title="Tabela periodicã-a elementsãlor" data-language-autonym="Armãneashti" data-language-local-name="Aromanian" class="interlanguage-link-target"><span>Armãneashti</span></a></li><li class="interlanguage-link interwiki-as mw-list-item"><a href="https://as.wikipedia.org/wiki/%E0%A6%AA%E0%A7%B0%E0%A7%8D%E0%A6%AF%E0%A6%BE%E0%A6%AC%E0%A7%83%E0%A6%A4%E0%A7%8D%E0%A6%A4_%E0%A6%A4%E0%A6%BE%E0%A6%B2%E0%A6%BF%E0%A6%95%E0%A6%BE" title="পৰ্যাবৃত্ত তালিকা – Assamese" lang="as" hreflang="as" data-title="পৰ্যাবৃত্ত তালিকা" data-language-autonym="অসমীয়া" data-language-local-name="Assamese" class="interlanguage-link-target"><span>অসমীয়া</span></a></li><li class="interlanguage-link interwiki-ast mw-list-item"><a href="https://ast.wikipedia.org/wiki/Tabla_peri%C3%B3dica" title="Tabla periódica – Asturian" lang="ast" hreflang="ast" data-title="Tabla periódica" data-language-autonym="Asturianu" data-language-local-name="Asturian" class="interlanguage-link-target"><span>Asturianu</span></a></li><li class="interlanguage-link interwiki-awa mw-list-item"><a href="https://awa.wikipedia.org/wiki/%E0%A4%AA%E0%A5%80%E0%A4%B0%E0%A4%BF%E0%A4%AF%E0%A5%89%E0%A4%A1%E0%A4%BF%E0%A4%95_%E0%A4%9F%E0%A5%87%E0%A4%AC%E0%A4%B2" title="पीरियॉडिक टेबल – Awadhi" lang="awa" hreflang="awa" data-title="पीरियॉडिक टेबल" data-language-autonym="अवधी" data-language-local-name="Awadhi" class="interlanguage-link-target"><span>अवधी</span></a></li><li class="interlanguage-link interwiki-gn mw-list-item"><a href="https://gn.wikipedia.org/wiki/Ap%E1%BB%B9i_k%C3%ADmiko_rechaukaha" title="Apỹi kímiko rechaukaha – Guarani" lang="gn" hreflang="gn" data-title="Apỹi kímiko rechaukaha" data-language-autonym="Avañe'ẽ" data-language-local-name="Guarani" class="interlanguage-link-target"><span>Avañe'ẽ</span></a></li><li class="interlanguage-link interwiki-az mw-list-item"><a href="https://az.wikipedia.org/wiki/Kimy%C9%99vi_elementl%C9%99rin_d%C3%B6vri_sistemi" title="Kimyəvi elementlərin dövri sistemi – Azerbaijani" lang="az" hreflang="az" data-title="Kimyəvi elementlərin dövri sistemi" data-language-autonym="Azərbaycanca" data-language-local-name="Azerbaijani" class="interlanguage-link-target"><span>Azərbaycanca</span></a></li><li class="interlanguage-link interwiki-azb mw-list-item"><a href="https://azb.wikipedia.org/wiki/%D8%B4%DB%8C%D9%85%DB%8C%D8%A7%DB%8C%DB%8C_%D8%A7%D9%84%D9%85%D9%86%D8%AA%D9%84%D8%B1_%D8%AA%D8%A7%D8%A8%D9%84%D9%88%D8%B3%D9%88" title="شیمیایی المنتلر تابلوسو – South Azerbaijani" lang="azb" hreflang="azb" data-title="شیمیایی المنتلر تابلوسو" data-language-autonym="تۆرکجه" data-language-local-name="South Azerbaijani" class="interlanguage-link-target"><span>تۆرکجه</span></a></li><li class="interlanguage-link interwiki-ban mw-list-item"><a href="https://ban.wikipedia.org/wiki/Tab%C3%A9l_p%C3%A9riodik" title="Tabél périodik – Balinese" lang="ban" hreflang="ban" data-title="Tabél périodik" data-language-autonym="Basa Bali" data-language-local-name="Balinese" class="interlanguage-link-target"><span>Basa Bali</span></a></li><li class="interlanguage-link interwiki-bn mw-list-item"><a href="https://bn.wikipedia.org/wiki/%E0%A6%AA%E0%A6%B0%E0%A7%8D%E0%A6%AF%E0%A6%BE%E0%A6%AF%E0%A6%BC_%E0%A6%B8%E0%A6%BE%E0%A6%B0%E0%A6%A3%E0%A6%BF" title="পর্যায় সারণি – Bangla" lang="bn" hreflang="bn" data-title="পর্যায় সারণি" data-language-autonym="বাংলা" data-language-local-name="Bangla" class="interlanguage-link-target"><span>বাংলা</span></a></li><li class="interlanguage-link interwiki-zh-min-nan mw-list-item"><a href="https://zh-min-nan.wikipedia.org/wiki/Chiu-k%C3%AE-pi%C3%A1u" title="Chiu-kî-piáu – Minnan" lang="nan" hreflang="nan" data-title="Chiu-kî-piáu" data-language-autonym="閩南語 / Bân-lâm-gú" data-language-local-name="Minnan" class="interlanguage-link-target"><span>閩南語 / Bân-lâm-gú</span></a></li><li class="interlanguage-link interwiki-ba mw-list-item"><a href="https://ba.wikipedia.org/wiki/%D0%A5%D0%B8%D0%BC%D0%B8%D0%BA_%D1%8D%D0%BB%D0%B5%D0%BC%D0%B5%D0%BD%D1%82%D1%82%D0%B0%D1%80%D2%99%D1%8B%D2%A3_%D0%BF%D0%B5%D1%80%D0%B8%D0%BE%D0%B4%D0%B8%D0%BA_%D1%81%D0%B8%D1%81%D1%82%D0%B5%D0%BC%D0%B0%D2%BB%D1%8B" title="Химик элементтарҙың периодик системаһы – Bashkir" lang="ba" hreflang="ba" data-title="Химик элементтарҙың периодик системаһы" data-language-autonym="Башҡортса" data-language-local-name="Bashkir" class="interlanguage-link-target"><span>Башҡортса</span></a></li><li class="interlanguage-link interwiki-be mw-list-item"><a href="https://be.wikipedia.org/wiki/%D0%9F%D0%B5%D1%80%D1%8B%D1%8F%D0%B4%D1%8B%D1%87%D0%BD%D0%B0%D1%8F_%D1%81%D1%96%D1%81%D1%82%D1%8D%D0%BC%D0%B0_%D1%8D%D0%BB%D0%B5%D0%BC%D0%B5%D0%BD%D1%82%D0%B0%D1%9E" title="Перыядычная сістэма элементаў – Belarusian" lang="be" hreflang="be" data-title="Перыядычная сістэма элементаў" data-language-autonym="Беларуская" data-language-local-name="Belarusian" class="interlanguage-link-target"><span>Беларуская</span></a></li><li class="interlanguage-link interwiki-be-x-old mw-list-item"><a href="https://be-tarask.wikipedia.org/wiki/%D0%9F%D1%8D%D1%80%D1%8B%D1%8F%D0%B4%D1%8B%D1%87%D0%BD%D0%B0%D1%8F_%D1%81%D1%8B%D1%81%D1%82%D1%8D%D0%BC%D0%B0_%D1%85%D1%96%D0%BC%D1%96%D1%87%D0%BD%D1%8B%D1%85_%D1%8D%D0%BB%D0%B5%D0%BC%D1%8D%D0%BD%D1%82%D0%B0%D1%9E" title="Пэрыядычная сыстэма хімічных элемэнтаў – Belarusian (Taraškievica orthography)" lang="be-tarask" hreflang="be-tarask" data-title="Пэрыядычная сыстэма хімічных элемэнтаў" data-language-autonym="Беларуская (тарашкевіца)" data-language-local-name="Belarusian (Taraškievica orthography)" class="interlanguage-link-target"><span>Беларуская (тарашкевіца)</span></a></li><li class="interlanguage-link interwiki-bh mw-list-item"><a href="https://bh.wikipedia.org/wiki/%E0%A4%AA%E0%A5%80%E0%A4%B0%E0%A4%BF%E0%A4%AF%E0%A5%89%E0%A4%A1%E0%A4%BF%E0%A4%95_%E0%A4%9F%E0%A5%87%E0%A4%AC%E0%A4%B2" title="पीरियॉडिक टेबल – Bhojpuri" lang="bh" hreflang="bh" data-title="पीरियॉडिक टेबल" data-language-autonym="भोजपुरी" data-language-local-name="Bhojpuri" class="interlanguage-link-target"><span>भोजपुरी</span></a></li><li class="interlanguage-link interwiki-bcl mw-list-item"><a href="https://bcl.wikipedia.org/wiki/Peryodikong_tableta" title="Peryodikong tableta – Central Bikol" lang="bcl" hreflang="bcl" data-title="Peryodikong tableta" data-language-autonym="Bikol Central" data-language-local-name="Central Bikol" class="interlanguage-link-target"><span>Bikol Central</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%9F%D0%B5%D1%80%D0%B8%D0%BE%D0%B4%D0%B8%D1%87%D0%BD%D0%B0_%D1%81%D0%B8%D1%81%D1%82%D0%B5%D0%BC%D0%B0" title="Периодична система – Bulgarian" lang="bg" hreflang="bg" data-title="Периодична система" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-bar mw-list-item"><a href="https://bar.wikipedia.org/wiki/Periodnsystem" title="Periodnsystem – Bavarian" lang="bar" hreflang="bar" data-title="Periodnsystem" data-language-autonym="Boarisch" data-language-local-name="Bavarian" class="interlanguage-link-target"><span>Boarisch</span></a></li><li class="interlanguage-link interwiki-bo mw-list-item"><a href="https://bo.wikipedia.org/wiki/%E0%BD%A2%E0%BE%A9%E0%BC%8B%E0%BD%A2%E0%BE%AB%E0%BD%A6%E0%BC%8B%E0%BD%80%E0%BE%B1%E0%BD%B2%E0%BC%8B%E0%BD%91%E0%BD%B4%E0%BD%A6%E0%BC%8B%E0%BD%A0%E0%BD%81%E0%BD%BC%E0%BD%A2%E0%BC%8B%E0%BD%A2%E0%BD%BA%E0%BD%A0%E0%BD%B4%E0%BC%8B%E0%BD%98%E0%BD%B2%E0%BD%82%E0%BC%8D" title="རྩ་རྫས་ཀྱི་དུས་འཁོར་རེའུ་མིག། – Tibetan" lang="bo" hreflang="bo" data-title="རྩ་རྫས་ཀྱི་དུས་འཁོར་རེའུ་མིག།" data-language-autonym="བོད་ཡིག" data-language-local-name="Tibetan" class="interlanguage-link-target"><span>བོད་ཡིག</span></a></li><li class="interlanguage-link interwiki-bs mw-list-item"><a href="https://bs.wikipedia.org/wiki/Periodni_sistem_elemenata" title="Periodni sistem elemenata – Bosnian" lang="bs" hreflang="bs" data-title="Periodni sistem elemenata" data-language-autonym="Bosanski" data-language-local-name="Bosnian" class="interlanguage-link-target"><span>Bosanski</span></a></li><li class="interlanguage-link interwiki-br mw-list-item"><a href="https://br.wikipedia.org/wiki/Taolenn_beriodek_an_elfenno%C3%B9" title="Taolenn beriodek an elfennoù – Breton" lang="br" hreflang="br" data-title="Taolenn beriodek an elfennoù" data-language-autonym="Brezhoneg" data-language-local-name="Breton" class="interlanguage-link-target"><span>Brezhoneg</span></a></li><li class="interlanguage-link interwiki-bxr mw-list-item"><a href="https://bxr.wikipedia.org/wiki/%D2%AE%D0%B5%D0%BB%D1%85%D1%8D_%D1%81%D0%B8%D1%81%D1%82%D0%B5%D0%BC%D1%8D" title="Үелхэ системэ – Russia Buriat" lang="bxr" hreflang="bxr" data-title="Үелхэ системэ" data-language-autonym="Буряад" data-language-local-name="Russia Buriat" class="interlanguage-link-target"><span>Буряад</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Taula_peri%C3%B2dica" title="Taula periòdica – Catalan" lang="ca" hreflang="ca" data-title="Taula periòdica" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cv mw-list-item"><a href="https://cv.wikipedia.org/wiki/%D0%AD%D0%BB%D0%B5%D0%BC%D0%B5%D0%BD%D1%82%D1%81%D0%B5%D0%BD_%D0%BF%D0%B5%D1%80%D0%B8%D0%BE%D0%B4%D0%BB%D0%B0_%D1%82%D1%8B%D1%82%C4%83%D0%BC%C4%95" title="Элементсен периодла тытăмĕ – Chuvash" lang="cv" hreflang="cv" data-title="Элементсен периодла тытăмĕ" data-language-autonym="Чӑвашла" data-language-local-name="Chuvash" class="interlanguage-link-target"><span>Чӑвашла</span></a></li><li class="interlanguage-link interwiki-ceb mw-list-item"><a href="https://ceb.wikipedia.org/wiki/Talaang_peryodiko" title="Talaang peryodiko – Cebuano" lang="ceb" hreflang="ceb" data-title="Talaang peryodiko" data-language-autonym="Cebuano" data-language-local-name="Cebuano" class="interlanguage-link-target"><span>Cebuano</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Periodick%C3%A1_tabulka" title="Periodická tabulka – Czech" lang="cs" hreflang="cs" data-title="Periodická tabulka" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-sn mw-list-item"><a href="https://sn.wikipedia.org/wiki/Chapotera_cheNhangande_Dzakadevana" title="Chapotera cheNhangande Dzakadevana – Shona" lang="sn" hreflang="sn" data-title="Chapotera cheNhangande Dzakadevana" data-language-autonym="ChiShona" data-language-local-name="Shona" class="interlanguage-link-target"><span>ChiShona</span></a></li><li class="interlanguage-link interwiki-co mw-list-item"><a href="https://co.wikipedia.org/wiki/Tavola_periodica" title="Tavola periodica – Corsican" lang="co" hreflang="co" data-title="Tavola periodica" data-language-autonym="Corsu" data-language-local-name="Corsican" class="interlanguage-link-target"><span>Corsu</span></a></li><li class="interlanguage-link interwiki-cy mw-list-item"><a href="https://cy.wikipedia.org/wiki/Tabl_cyfnodol" title="Tabl cyfnodol – Welsh" lang="cy" hreflang="cy" data-title="Tabl cyfnodol" data-language-autonym="Cymraeg" data-language-local-name="Welsh" class="interlanguage-link-target"><span>Cymraeg</span></a></li><li class="interlanguage-link interwiki-da badge-Q17559452 badge-recommendedarticle mw-list-item" title="recommended article"><a href="https://da.wikipedia.org/wiki/Periodiske_system" title="Periodiske system – Danish" lang="da" hreflang="da" data-title="Periodiske system" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-ary mw-list-item"><a href="https://ary.wikipedia.org/wiki/%D8%B7%D8%A7%D8%A8%D9%84%D9%88_%D8%AF%D9%88%D8%B1%D9%8A" title="طابلو دوري – Moroccan Arabic" lang="ary" hreflang="ary" data-title="طابلو دوري" data-language-autonym="الدارجة" data-language-local-name="Moroccan Arabic" class="interlanguage-link-target"><span>الدارجة</span></a></li><li class="interlanguage-link interwiki-se mw-list-item"><a href="https://se.wikipedia.org/wiki/Periodala%C5%A1_tabealla" title="Periodalaš tabealla – Northern Sami" lang="se" hreflang="se" data-title="Periodalaš tabealla" data-language-autonym="Davvisámegiella" data-language-local-name="Northern Sami" class="interlanguage-link-target"><span>Davvisámegiella</span></a></li><li class="interlanguage-link interwiki-de badge-Q17437796 badge-featuredarticle mw-list-item" title="featured article badge"><a href="https://de.wikipedia.org/wiki/Periodensystem" title="Periodensystem – German" lang="de" hreflang="de" data-title="Periodensystem" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-dv mw-list-item"><a href="https://dv.wikipedia.org/wiki/%DE%95%DE%A9%DE%83%DE%A8%DE%87%DE%A6%DE%91%DE%A8%DE%86%DE%B0_%DE%8C%DE%A7%DE%88%DE%A6%DE%8D%DE%AA" title="ޕީރިއަޑިކް ތާވަލު – Divehi" lang="dv" hreflang="dv" data-title="ޕީރިއަޑިކް ތާވަލު" data-language-autonym="ދިވެހިބަސް" data-language-local-name="Divehi" class="interlanguage-link-target"><span>ދިވެހިބަސް</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Keemiliste_elementide_perioodilisuss%C3%BCsteem" title="Keemiliste elementide perioodilisussüsteem – Estonian" lang="et" hreflang="et" data-title="Keemiliste elementide perioodilisussüsteem" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/%CE%A0%CE%B5%CF%81%CE%B9%CE%BF%CE%B4%CE%B9%CE%BA%CF%8C%CF%82_%CF%80%CE%AF%CE%BD%CE%B1%CE%BA%CE%B1%CF%82_%CF%84%CF%89%CE%BD_%CF%87%CE%B7%CE%BC%CE%B9%CE%BA%CF%8E%CE%BD_%CF%83%CF%84%CE%BF%CE%B9%CF%87%CE%B5%CE%AF%CF%89%CE%BD" title="Περιοδικός πίνακας των χημικών στοιχείων – Greek" lang="el" hreflang="el" data-title="Περιοδικός πίνακας των χημικών στοιχείων" data-language-autonym="Ελληνικά" data-language-local-name="Greek" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Tabla_peri%C3%B3dica_de_los_elementos" title="Tabla periódica de los elementos – Spanish" lang="es" hreflang="es" data-title="Tabla periódica de los elementos" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/Perioda_tabelo" title="Perioda tabelo – Esperanto" lang="eo" hreflang="eo" data-title="Perioda tabelo" data-language-autonym="Esperanto" data-language-local-name="Esperanto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-ext mw-list-item"><a href="https://ext.wikipedia.org/wiki/Tabra_peri%C3%BAdica_e_los_elementus" title="Tabra periúdica e los elementus – Extremaduran" lang="ext" hreflang="ext" data-title="Tabra periúdica e los elementus" data-language-autonym="Estremeñu" data-language-local-name="Extremaduran" class="interlanguage-link-target"><span>Estremeñu</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/Taula_periodikoa" title="Taula periodikoa – Basque" lang="eu" hreflang="eu" data-title="Taula periodikoa" data-language-autonym="Euskara" data-language-local-name="Basque" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fa badge-Q17437798 badge-goodarticle mw-list-item" title="good article badge"><a href="https://fa.wikipedia.org/wiki/%D8%AC%D8%AF%D9%88%D9%84_%D8%AA%D9%86%D8%A7%D9%88%D8%A8%DB%8C" title="جدول تناوبی – Persian" lang="fa" hreflang="fa" data-title="جدول تناوبی" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-hif mw-list-item"><a href="https://hif.wikipedia.org/wiki/Periodic_table" title="Periodic table – Fiji Hindi" lang="hif" hreflang="hif" data-title="Periodic table" data-language-autonym="Fiji Hindi" data-language-local-name="Fiji Hindi" class="interlanguage-link-target"><span>Fiji Hindi</span></a></li><li class="interlanguage-link interwiki-fo mw-list-item"><a href="https://fo.wikipedia.org/wiki/Skei%C3%B0bundna_skipanin" title="Skeiðbundna skipanin – Faroese" lang="fo" hreflang="fo" data-title="Skeiðbundna skipanin" data-language-autonym="Føroyskt" data-language-local-name="Faroese" class="interlanguage-link-target"><span>Føroyskt</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Tableau_p%C3%A9riodique_des_%C3%A9l%C3%A9ments" title="Tableau périodique des éléments – French" lang="fr" hreflang="fr" data-title="Tableau périodique des éléments" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-fy mw-list-item"><a href="https://fy.wikipedia.org/wiki/Periodyk_systeem_fan_de_eleminten" title="Periodyk systeem fan de eleminten – Western Frisian" lang="fy" hreflang="fy" data-title="Periodyk systeem fan de eleminten" data-language-autonym="Frysk" data-language-local-name="Western Frisian" class="interlanguage-link-target"><span>Frysk</span></a></li><li class="interlanguage-link interwiki-fur mw-list-item"><a href="https://fur.wikipedia.org/wiki/Tabele_periodiche" title="Tabele periodiche – Friulian" lang="fur" hreflang="fur" data-title="Tabele periodiche" data-language-autonym="Furlan" data-language-local-name="Friulian" class="interlanguage-link-target"><span>Furlan</span></a></li><li class="interlanguage-link interwiki-ga mw-list-item"><a href="https://ga.wikipedia.org/wiki/T%C3%A1bla_peiriadach" title="Tábla peiriadach – Irish" lang="ga" hreflang="ga" data-title="Tábla peiriadach" data-language-autonym="Gaeilge" data-language-local-name="Irish" class="interlanguage-link-target"><span>Gaeilge</span></a></li><li class="interlanguage-link interwiki-gv mw-list-item"><a href="https://gv.wikipedia.org/wiki/Taabyl_reiltagh_ny_bunstooghyn" title="Taabyl reiltagh ny bunstooghyn – Manx" lang="gv" hreflang="gv" data-title="Taabyl reiltagh ny bunstooghyn" data-language-autonym="Gaelg" data-language-local-name="Manx" class="interlanguage-link-target"><span>Gaelg</span></a></li><li class="interlanguage-link interwiki-gd mw-list-item"><a href="https://gd.wikipedia.org/wiki/Cl%C3%A0r_pillteach" title="Clàr pillteach – Scottish Gaelic" lang="gd" hreflang="gd" data-title="Clàr pillteach" data-language-autonym="Gàidhlig" data-language-local-name="Scottish Gaelic" class="interlanguage-link-target"><span>Gàidhlig</span></a></li><li class="interlanguage-link interwiki-gl badge-Q17437796 badge-featuredarticle mw-list-item" title="featured article badge"><a href="https://gl.wikipedia.org/wiki/T%C3%A1boa_peri%C3%B3dica_dos_elementos" title="Táboa periódica dos elementos – Galician" lang="gl" hreflang="gl" data-title="Táboa periódica dos elementos" data-language-autonym="Galego" data-language-local-name="Galician" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-inh mw-list-item"><a href="https://inh.wikipedia.org/wiki/%D0%A5%D0%B8%D0%BC%D0%B5_%D1%8D%D0%BB%D0%B5%D0%BC%D0%B5%D0%BD%D1%82%D0%B8%D0%B9_%D0%BC%D1%83%D1%80%D0%B0_%D1%81%D0%B8%D1%81%D1%82%D0%B5%D0%BC%D0%B0" title="Химе элементий мура система – Ingush" lang="inh" hreflang="inh" data-title="Химе элементий мура система" data-language-autonym="ГӀалгӀай" data-language-local-name="Ingush" class="interlanguage-link-target"><span>ГӀалгӀай</span></a></li><li class="interlanguage-link interwiki-gan mw-list-item"><a href="https://gan.wikipedia.org/wiki/%E5%85%83%E7%B4%A0%E9%80%B1%E6%9C%9F%E8%A1%A8" title="元素週期表 – Gan" lang="gan" hreflang="gan" data-title="元素週期表" data-language-autonym="贛語" data-language-local-name="Gan" class="interlanguage-link-target"><span>贛語</span></a></li><li class="interlanguage-link interwiki-ki mw-list-item"><a href="https://ki.wikipedia.org/wiki/Metha_Njokereri" title="Metha Njokereri – Kikuyu" lang="ki" hreflang="ki" data-title="Metha Njokereri" data-language-autonym="Gĩkũyũ" data-language-local-name="Kikuyu" class="interlanguage-link-target"><span>Gĩkũyũ</span></a></li><li class="interlanguage-link interwiki-gu mw-list-item"><a href="https://gu.wikipedia.org/wiki/%E0%AA%86%E0%AA%B5%E0%AA%B0%E0%AB%8D%E0%AA%A4_%E0%AA%95%E0%AB%8B%E0%AA%B7%E0%AB%8D%E0%AA%9F%E0%AA%95" title="આવર્ત કોષ્ટક – Gujarati" lang="gu" hreflang="gu" data-title="આવર્ત કોષ્ટક" data-language-autonym="ગુજરાતી" data-language-local-name="Gujarati" class="interlanguage-link-target"><span>ગુજરાતી</span></a></li><li class="interlanguage-link interwiki-hak mw-list-item"><a href="https://hak.wikipedia.org/wiki/Ngi%C3%A8n-su_ch%C3%BB-kh%C3%AC-p%C3%A9u" title="Ngièn-su chû-khì-péu – Hakka Chinese" lang="hak" hreflang="hak" data-title="Ngièn-su chû-khì-péu" data-language-autonym="客家語 / Hak-kâ-ngî" data-language-local-name="Hakka Chinese" class="interlanguage-link-target"><span>客家語 / Hak-kâ-ngî</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EC%A3%BC%EA%B8%B0%EC%9C%A8%ED%91%9C" title="주기율표 – Korean" lang="ko" hreflang="ko" data-title="주기율표" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/%D5%8A%D5%A1%D6%80%D5%A2%D5%A5%D6%80%D5%A1%D5%AF%D5%A1%D5%B6_%D5%A1%D5%B2%D5%B5%D5%B8%D6%82%D5%BD%D5%A1%D5%AF" title="Պարբերական աղյուսակ – Armenian" lang="hy" hreflang="hy" data-title="Պարբերական աղյուսակ" data-language-autonym="Հայերեն" data-language-local-name="Armenian" class="interlanguage-link-target"><span>Հայերեն</span></a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%86%E0%A4%B5%E0%A4%B0%E0%A5%8D%E0%A4%A4_%E0%A4%B8%E0%A4%BE%E0%A4%B0%E0%A4%A3%E0%A5%80" title="आवर्त सारणी – Hindi" lang="hi" hreflang="hi" data-title="आवर्त सारणी" data-language-autonym="हिन्दी" data-language-local-name="Hindi" class="interlanguage-link-target"><span>हिन्दी</span></a></li><li class="interlanguage-link interwiki-hr badge-Q17437796 badge-featuredarticle mw-list-item" title="featured article badge"><a href="https://hr.wikipedia.org/wiki/Periodni_sustav_elemenata" title="Periodni sustav elemenata – Croatian" lang="hr" hreflang="hr" data-title="Periodni sustav elemenata" data-language-autonym="Hrvatski" data-language-local-name="Croatian" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-io mw-list-item"><a href="https://io.wikipedia.org/wiki/Periodala_tabelo" title="Periodala tabelo – Ido" lang="io" hreflang="io" data-title="Periodala tabelo" data-language-autonym="Ido" data-language-local-name="Ido" class="interlanguage-link-target"><span>Ido</span></a></li><li class="interlanguage-link interwiki-ilo mw-list-item"><a href="https://ilo.wikipedia.org/wiki/Periodiko_a_lamisaan_dagiti_elemento" title="Periodiko a lamisaan dagiti elemento – Iloko" lang="ilo" hreflang="ilo" data-title="Periodiko a lamisaan dagiti elemento" data-language-autonym="Ilokano" data-language-local-name="Iloko" class="interlanguage-link-target"><span>Ilokano</span></a></li><li class="interlanguage-link interwiki-bpy mw-list-item"><a href="https://bpy.wikipedia.org/wiki/%E0%A6%AA%E0%A6%B0%E0%A7%8D%E0%A6%AF%E0%A6%BE%E0%A6%AF%E0%A6%BC_%E0%A6%B8%E0%A6%BE%E0%A6%B0%E0%A6%A3%E0%A7%80" title="পর্যায় সারণী – Bishnupriya" lang="bpy" hreflang="bpy" data-title="পর্যায় সারণী" data-language-autonym="বিষ্ণুপ্রিয়া মণিপুরী" data-language-local-name="Bishnupriya" class="interlanguage-link-target"><span>বিষ্ণুপ্রিয়া মণিপুরী</span></a></li><li class="interlanguage-link interwiki-id badge-Q17437796 badge-featuredarticle mw-list-item" title="featured article badge"><a href="https://id.wikipedia.org/wiki/Tabel_periodik" title="Tabel periodik – Indonesian" lang="id" hreflang="id" data-title="Tabel periodik" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-ia mw-list-item"><a href="https://ia.wikipedia.org/wiki/Tabella_periodic_del_elementos" title="Tabella periodic del elementos – Interlingua" lang="ia" hreflang="ia" data-title="Tabella periodic del elementos" data-language-autonym="Interlingua" data-language-local-name="Interlingua" class="interlanguage-link-target"><span>Interlingua</span></a></li><li class="interlanguage-link interwiki-ie mw-list-item"><a href="https://ie.wikipedia.org/wiki/Tabelle_periodic" title="Tabelle periodic – Interlingue" lang="ie" hreflang="ie" data-title="Tabelle periodic" data-language-autonym="Interlingue" data-language-local-name="Interlingue" class="interlanguage-link-target"><span>Interlingue</span></a></li><li class="interlanguage-link interwiki-os mw-list-item"><a href="https://os.wikipedia.org/wiki/%D0%AD%D0%BB%D0%B5%D0%BC%D0%B5%D0%BD%D1%82%D1%82%D1%8B_%D0%BF%D0%B5%D1%80%D0%B8%D0%BE%D0%B4%D0%BE%D0%BD_%D1%81%D0%B8%D1%81%D1%82%D0%B5%D0%BC%C3%A6" title="Элементты периодон системæ – Ossetic" lang="os" hreflang="os" data-title="Элементты периодон системæ" data-language-autonym="Ирон" data-language-local-name="Ossetic" class="interlanguage-link-target"><span>Ирон</span></a></li><li class="interlanguage-link interwiki-zu mw-list-item"><a href="https://zu.wikipedia.org/wiki/Icansi_lezinhlwa" title="Icansi lezinhlwa – Zulu" lang="zu" hreflang="zu" data-title="Icansi lezinhlwa" data-language-autonym="IsiZulu" data-language-local-name="Zulu" class="interlanguage-link-target"><span>IsiZulu</span></a></li><li class="interlanguage-link interwiki-is mw-list-item"><a href="https://is.wikipedia.org/wiki/Lotukerfi%C3%B0" title="Lotukerfið – Icelandic" lang="is" hreflang="is" data-title="Lotukerfið" data-language-autonym="Íslenska" data-language-local-name="Icelandic" class="interlanguage-link-target"><span>Íslenska</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Tavola_periodica_degli_elementi" title="Tavola periodica degli elementi – Italian" lang="it" hreflang="it" data-title="Tavola periodica degli elementi" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%94%D7%98%D7%91%D7%9C%D7%94_%D7%94%D7%9E%D7%97%D7%96%D7%95%D7%A8%D7%99%D7%AA" title="הטבלה המחזורית – Hebrew" lang="he" hreflang="he" data-title="הטבלה המחזורית" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-jv mw-list-item"><a href="https://jv.wikipedia.org/wiki/Prat%C3%A9lan_unsur_miturut_lambang" title="Pratélan unsur miturut lambang – Javanese" lang="jv" hreflang="jv" data-title="Pratélan unsur miturut lambang" data-language-autonym="Jawa" data-language-local-name="Javanese" class="interlanguage-link-target"><span>Jawa</span></a></li><li class="interlanguage-link interwiki-kn mw-list-item"><a href="https://kn.wikipedia.org/wiki/%E0%B2%86%E0%B2%B5%E0%B2%B0%E0%B3%8D%E0%B2%A4_%E0%B2%95%E0%B3%8B%E0%B2%B7%E0%B3%8D%E0%B2%9F%E0%B2%95" title="ಆವರ್ತ ಕೋಷ್ಟಕ – Kannada" lang="kn" hreflang="kn" data-title="ಆವರ್ತ ಕೋಷ್ಟಕ" data-language-autonym="ಕನ್ನಡ" data-language-local-name="Kannada" class="interlanguage-link-target"><span>ಕನ್ನಡ</span></a></li><li class="interlanguage-link interwiki-pam mw-list-item"><a href="https://pam.wikipedia.org/wiki/Tablang_periodiku_da_ring_elementu" title="Tablang periodiku da ring elementu – Pampanga" lang="pam" hreflang="pam" data-title="Tablang periodiku da ring elementu" data-language-autonym="Kapampangan" data-language-local-name="Pampanga" class="interlanguage-link-target"><span>Kapampangan</span></a></li><li class="interlanguage-link interwiki-ka mw-list-item"><a href="https://ka.wikipedia.org/wiki/%E1%83%A5%E1%83%98%E1%83%9B%E1%83%98%E1%83%A3%E1%83%A0_%E1%83%94%E1%83%9A%E1%83%94%E1%83%9B%E1%83%94%E1%83%9C%E1%83%A2%E1%83%97%E1%83%90_%E1%83%9E%E1%83%94%E1%83%A0%E1%83%98%E1%83%9D%E1%83%93%E1%83%A3%E1%83%9A%E1%83%98_%E1%83%A1%E1%83%98%E1%83%A1%E1%83%A2%E1%83%94%E1%83%9B%E1%83%90" title="ქიმიურ ელემენტთა პერიოდული სისტემა – Georgian" lang="ka" hreflang="ka" data-title="ქიმიურ ელემენტთა პერიოდული სისტემა" data-language-autonym="ქართული" data-language-local-name="Georgian" class="interlanguage-link-target"><span>ქართული</span></a></li><li class="interlanguage-link interwiki-kk mw-list-item"><a href="https://kk.wikipedia.org/wiki/%D0%A5%D0%B8%D0%BC%D0%B8%D1%8F%D0%BB%D1%8B%D2%9B_%D1%8D%D0%BB%D0%B5%D0%BC%D0%B5%D0%BD%D1%82%D1%82%D0%B5%D1%80%D0%B4%D1%96%D2%A3_%D0%BF%D0%B5%D1%80%D0%B8%D0%BE%D0%B4%D1%82%D1%8B%D2%9B_%D0%B6%D2%AF%D0%B9%D0%B5%D1%81%D1%96" title="Химиялық элементтердің периодтық жүйесі – Kazakh" lang="kk" hreflang="kk" data-title="Химиялық элементтердің периодтық жүйесі" data-language-autonym="Қазақша" data-language-local-name="Kazakh" class="interlanguage-link-target"><span>Қазақша</span></a></li><li class="interlanguage-link interwiki-kw mw-list-item"><a href="https://kw.wikipedia.org/wiki/An_Vosen_Beriodek" title="An Vosen Beriodek – Cornish" lang="kw" hreflang="kw" data-title="An Vosen Beriodek" data-language-autonym="Kernowek" data-language-local-name="Cornish" class="interlanguage-link-target"><span>Kernowek</span></a></li><li class="interlanguage-link interwiki-sw mw-list-item"><a href="https://sw.wikipedia.org/wiki/Mfumo_radidia" title="Mfumo radidia – Swahili" lang="sw" hreflang="sw" data-title="Mfumo radidia" data-language-autonym="Kiswahili" data-language-local-name="Swahili" class="interlanguage-link-target"><span>Kiswahili</span></a></li><li class="interlanguage-link interwiki-kv mw-list-item"><a href="https://kv.wikipedia.org/wiki/%D0%A5%D0%B8%D0%BC%D0%B8%D1%8F_%D1%8D%D0%BB%D0%B5%D0%BC%D0%B5%D0%BD%D1%82%D1%8A%D1%8F%D1%81%D0%BB%D3%A7%D0%BD_%D0%BF%D0%B5%D1%80%D0%B8%D0%BE%D0%B4_%D1%81%D0%B8%D1%81%D1%82%D0%B5%D0%BC%D0%B0" title="Химия элементъяслӧн период система – Komi" lang="kv" hreflang="kv" data-title="Химия элементъяслӧн период система" data-language-autonym="Коми" data-language-local-name="Komi" class="interlanguage-link-target"><span>Коми</span></a></li><li class="interlanguage-link interwiki-ht mw-list-item"><a href="https://ht.wikipedia.org/wiki/Tablo_klasifikasyon_peryodik_eleman" title="Tablo klasifikasyon peryodik eleman – Haitian Creole" lang="ht" hreflang="ht" data-title="Tablo klasifikasyon peryodik eleman" data-language-autonym="Kreyòl ayisyen" data-language-local-name="Haitian Creole" class="interlanguage-link-target"><span>Kreyòl ayisyen</span></a></li><li class="interlanguage-link interwiki-gcr mw-list-item"><a href="https://gcr.wikipedia.org/wiki/Tablo_p%C3%A9ryodik_di_s%C3%A9_%C3%A9l%C3%A9man" title="Tablo péryodik di sé éléman – Guianan Creole" lang="gcr" hreflang="gcr" data-title="Tablo péryodik di sé éléman" data-language-autonym="Kriyòl gwiyannen" data-language-local-name="Guianan Creole" class="interlanguage-link-target"><span>Kriyòl gwiyannen</span></a></li><li class="interlanguage-link interwiki-ku mw-list-item"><a href="https://ku.wikipedia.org/wiki/S%C3%AEstema_vedor%C3%AE_ya_elementan" title="Sîstema vedorî ya elementan – Kurdish" lang="ku" hreflang="ku" data-title="Sîstema vedorî ya elementan" data-language-autonym="Kurdî" data-language-local-name="Kurdish" class="interlanguage-link-target"><span>Kurdî</span></a></li><li class="interlanguage-link interwiki-ky mw-list-item"><a href="https://ky.wikipedia.org/wiki/%D0%AD%D0%BB%D0%B5%D0%BC%D0%B5%D0%BD%D1%82%D1%82%D0%B5%D1%80_%D0%BC%D0%B5%D0%B7%D0%B3%D0%B8%D0%BB%D0%B4%D0%B8%D0%BA_%D1%81%D0%B8%D1%81%D1%82%D0%B5%D0%BC%D0%B0%D1%81%D1%8B" title="Элементтер мезгилдик системасы – Kyrgyz" lang="ky" hreflang="ky" data-title="Элементтер мезгилдик системасы" data-language-autonym="Кыргызча" data-language-local-name="Kyrgyz" class="interlanguage-link-target"><span>Кыргызча</span></a></li><li class="interlanguage-link interwiki-lld mw-list-item"><a href="https://lld.wikipedia.org/wiki/Tabela_periodica_di_elemenc" title="Tabela periodica di elemenc – Ladin" lang="lld" hreflang="lld" data-title="Tabela periodica di elemenc" data-language-autonym="Ladin" data-language-local-name="Ladin" class="interlanguage-link-target"><span>Ladin</span></a></li><li class="interlanguage-link interwiki-lo mw-list-item"><a href="https://lo.wikipedia.org/wiki/%E0%BA%95%E0%BA%B2%E0%BA%95%E0%BA%B0%E0%BA%A5%E0%BA%B2%E0%BA%87%E0%BA%97%E0%BA%B2%E0%BA%94" title="ຕາຕະລາງທາດ – Lao" lang="lo" hreflang="lo" data-title="ຕາຕະລາງທາດ" data-language-autonym="ລາວ" data-language-local-name="Lao" class="interlanguage-link-target"><span>ລາວ</span></a></li><li class="interlanguage-link interwiki-la mw-list-item"><a href="https://la.wikipedia.org/wiki/Systema_periodicum" title="Systema periodicum – Latin" lang="la" hreflang="la" data-title="Systema periodicum" data-language-autonym="Latina" data-language-local-name="Latin" class="interlanguage-link-target"><span>Latina</span></a></li><li class="interlanguage-link interwiki-lv mw-list-item"><a href="https://lv.wikipedia.org/wiki/%C4%B6%C4%ABmisko_elementu_periodisk%C4%81_tabula" title="Ķīmisko elementu periodiskā tabula – Latvian" lang="lv" hreflang="lv" data-title="Ķīmisko elementu periodiskā tabula" data-language-autonym="Latviešu" data-language-local-name="Latvian" class="interlanguage-link-target"><span>Latviešu</span></a></li><li class="interlanguage-link interwiki-lb mw-list-item"><a href="https://lb.wikipedia.org/wiki/Periodesystem_vun_den_Elementer" title="Periodesystem vun den Elementer – Luxembourgish" lang="lb" hreflang="lb" data-title="Periodesystem vun den Elementer" data-language-autonym="Lëtzebuergesch" data-language-local-name="Luxembourgish" class="interlanguage-link-target"><span>Lëtzebuergesch</span></a></li><li class="interlanguage-link interwiki-lez mw-list-item"><a href="https://lez.wikipedia.org/wiki/%D0%A5%D0%B8%D0%BC%D0%B8%D1%8F%D0%B4%D0%B8%D0%BD_%D1%8D%D0%BB%D0%B5%D0%BC%D0%B5%D0%BD%D1%82%D1%80%D0%B8%D0%BD_%D0%B4%D0%B5%D0%B2%D0%B8%D1%80%D0%B4%D0%B8%D0%BD_%D1%81%D0%B8%D1%81%D1%82%D0%B5%D0%BC%D0%B0" title="Химиядин элементрин девирдин система – Lezghian" lang="lez" hreflang="lez" data-title="Химиядин элементрин девирдин система" data-language-autonym="Лезги" data-language-local-name="Lezghian" class="interlanguage-link-target"><span>Лезги</span></a></li><li class="interlanguage-link interwiki-lt mw-list-item"><a href="https://lt.wikipedia.org/wiki/Periodin%C4%97_element%C5%B3_lentel%C4%97" title="Periodinė elementų lentelė – Lithuanian" lang="lt" hreflang="lt" data-title="Periodinė elementų lentelė" data-language-autonym="Lietuvių" data-language-local-name="Lithuanian" class="interlanguage-link-target"><span>Lietuvių</span></a></li><li class="interlanguage-link interwiki-li mw-list-item"><a href="https://li.wikipedia.org/wiki/Periodiek_systeem_vaan_eleminte" title="Periodiek systeem vaan eleminte – Limburgish" lang="li" hreflang="li" data-title="Periodiek systeem vaan eleminte" data-language-autonym="Limburgs" data-language-local-name="Limburgish" class="interlanguage-link-target"><span>Limburgs</span></a></li><li class="interlanguage-link interwiki-ln mw-list-item"><a href="https://ln.wikipedia.org/wiki/Et%C3%A1nda_ya_bileko" title="Etánda ya bileko – Lingala" lang="ln" hreflang="ln" data-title="Etánda ya bileko" data-language-autonym="Lingála" data-language-local-name="Lingala" class="interlanguage-link-target"><span>Lingála</span></a></li><li class="interlanguage-link interwiki-jbo mw-list-item"><a href="https://jbo.wikipedia.org/wiki/dikni_selratni_cartu" title="dikni selratni cartu – Lojban" lang="jbo" hreflang="jbo" data-title="dikni selratni cartu" data-language-autonym="La .lojban." data-language-local-name="Lojban" class="interlanguage-link-target"><span>La .lojban.</span></a></li><li class="interlanguage-link interwiki-lmo mw-list-item"><a href="https://lmo.wikipedia.org/wiki/Taula_periodica" title="Taula periodica – Lombard" lang="lmo" hreflang="lmo" data-title="Taula periodica" data-language-autonym="Lombard" data-language-local-name="Lombard" class="interlanguage-link-target"><span>Lombard</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/K%C3%A9miai_elemek_peri%C3%B3dusos_rendszere" title="Kémiai elemek periódusos rendszere – Hungarian" lang="hu" hreflang="hu" data-title="Kémiai elemek periódusos rendszere" data-language-autonym="Magyar" data-language-local-name="Hungarian" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/%D0%9F%D0%B5%D1%80%D0%B8%D0%BE%D0%B4%D0%B5%D0%BD_%D1%81%D0%B8%D1%81%D1%82%D0%B5%D0%BC_%D0%BD%D0%B0_%D0%B5%D0%BB%D0%B5%D0%BC%D0%B5%D0%BD%D1%82%D0%B8%D1%82%D0%B5" title="Периоден систем на елементите – Macedonian" lang="mk" hreflang="mk" data-title="Периоден систем на елементите" data-language-autonym="Македонски" data-language-local-name="Macedonian" class="interlanguage-link-target"><span>Македонски</span></a></li><li class="interlanguage-link interwiki-mg mw-list-item"><a href="https://mg.wikipedia.org/wiki/Tabilaon%27ny_singa" title="Tabilaon'ny singa – Malagasy" lang="mg" hreflang="mg" data-title="Tabilaon'ny singa" data-language-autonym="Malagasy" data-language-local-name="Malagasy" class="interlanguage-link-target"><span>Malagasy</span></a></li><li class="interlanguage-link interwiki-ml mw-list-item"><a href="https://ml.wikipedia.org/wiki/%E0%B4%86%E0%B4%B5%E0%B5%BC%E0%B4%A4%E0%B5%8D%E0%B4%A4%E0%B4%A8%E0%B4%AA%E0%B5%8D%E0%B4%AA%E0%B4%9F%E0%B5%8D%E0%B4%9F%E0%B4%BF%E0%B4%95" title="ആവർത്തനപ്പട്ടിക – Malayalam" lang="ml" hreflang="ml" data-title="ആവർത്തനപ്പട്ടിക" data-language-autonym="മലയാളം" data-language-local-name="Malayalam" class="interlanguage-link-target"><span>മലയാളം</span></a></li><li class="interlanguage-link interwiki-mt mw-list-item"><a href="https://mt.wikipedia.org/wiki/Tavla_perjodika" title="Tavla perjodika – Maltese" lang="mt" hreflang="mt" data-title="Tavla perjodika" data-language-autonym="Malti" data-language-local-name="Maltese" class="interlanguage-link-target"><span>Malti</span></a></li><li class="interlanguage-link interwiki-mi mw-list-item"><a href="https://mi.wikipedia.org/wiki/Ripanga_p%C5%ABmotu" title="Ripanga pūmotu – Māori" lang="mi" hreflang="mi" data-title="Ripanga pūmotu" data-language-autonym="Māori" data-language-local-name="Māori" class="interlanguage-link-target"><span>Māori</span></a></li><li class="interlanguage-link interwiki-mr mw-list-item"><a href="https://mr.wikipedia.org/wiki/%E0%A4%86%E0%A4%B5%E0%A4%B0%E0%A5%8D%E0%A4%A4_%E0%A4%B8%E0%A4%BE%E0%A4%B0%E0%A4%A3%E0%A5%80" title="आवर्त सारणी – Marathi" lang="mr" hreflang="mr" data-title="आवर्त सारणी" data-language-autonym="मराठी" data-language-local-name="Marathi" class="interlanguage-link-target"><span>मराठी</span></a></li><li class="interlanguage-link interwiki-xmf mw-list-item"><a href="https://xmf.wikipedia.org/wiki/%E1%83%A5%E1%83%98%E1%83%9B%E1%83%98%E1%83%A3%E1%83%A0%E1%83%98_%E1%83%94%E1%83%9A%E1%83%94%E1%83%9B%E1%83%94%E1%83%9C%E1%83%A2%E1%83%94%E1%83%A4%E1%83%98%E1%83%A8_%E1%83%9E%E1%83%94%E1%83%A0%E1%83%98%E1%83%9D%E1%83%93%E1%83%A3%E1%83%9A%E1%83%98_%E1%83%A1%E1%83%98%E1%83%A1%E1%83%A2%E1%83%94%E1%83%9B%E1%83%90" title="ქიმიური ელემენტეფიშ პერიოდული სისტემა – Mingrelian" lang="xmf" hreflang="xmf" data-title="ქიმიური ელემენტეფიშ პერიოდული სისტემა" data-language-autonym="მარგალური" data-language-local-name="Mingrelian" class="interlanguage-link-target"><span>მარგალური</span></a></li><li class="interlanguage-link interwiki-arz mw-list-item"><a href="https://arz.wikipedia.org/wiki/%D8%AC%D8%AF%D9%88%D9%84_%D8%AF%D9%88%D8%B1%D9%89" title="جدول دورى – Egyptian Arabic" lang="arz" hreflang="arz" data-title="جدول دورى" data-language-autonym="مصرى" data-language-local-name="Egyptian Arabic" class="interlanguage-link-target"><span>مصرى</span></a></li><li class="interlanguage-link interwiki-mnw mw-list-item"><a href="https://mnw.wikipedia.org/wiki/%E1%80%9E%E1%80%B9%E1%81%9A%E1%80%AD%E1%80%A1%E1%80%84%E1%80%BA%E1%80%80%E1%80%AC%E1%80%9C" title="သ္ၚိအင်ကာလ – Mon" lang="mnw" hreflang="mnw" data-title="သ္ၚိအင်ကာလ" data-language-autonym="ဘာသာမန်" data-language-local-name="Mon" class="interlanguage-link-target"><span>ဘာသာမန်</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/Jadual_berkala" title="Jadual berkala – Malay" lang="ms" hreflang="ms" data-title="Jadual berkala" data-language-autonym="Bahasa Melayu" data-language-local-name="Malay" class="interlanguage-link-target"><span>Bahasa Melayu</span></a></li><li class="interlanguage-link interwiki-min mw-list-item"><a href="https://min.wikipedia.org/wiki/Tabel_periodik" title="Tabel periodik – Minangkabau" lang="min" hreflang="min" data-title="Tabel periodik" data-language-autonym="Minangkabau" data-language-local-name="Minangkabau" class="interlanguage-link-target"><span>Minangkabau</span></a></li><li class="interlanguage-link interwiki-cdo mw-list-item"><a href="https://cdo.wikipedia.org/wiki/Ngu%C3%B2ng-s%C3%B3_ci%C5%AD-g%C4%AD-bi%C4%93u" title="Nguòng-só ciŭ-gĭ-biēu – Mindong" lang="cdo" hreflang="cdo" data-title="Nguòng-só ciŭ-gĭ-biēu" data-language-autonym="閩東語 / Mìng-dĕ̤ng-ngṳ̄" data-language-local-name="Mindong" class="interlanguage-link-target"><span>閩東語 / Mìng-dĕ̤ng-ngṳ̄</span></a></li><li class="interlanguage-link interwiki-mwl mw-list-item"><a href="https://mwl.wikipedia.org/wiki/Tabela_peri%C3%B3dica" title="Tabela periódica – Mirandese" lang="mwl" hreflang="mwl" data-title="Tabela periódica" data-language-autonym="Mirandés" data-language-local-name="Mirandese" class="interlanguage-link-target"><span>Mirandés</span></a></li><li class="interlanguage-link interwiki-mn mw-list-item"><a href="https://mn.wikipedia.org/wiki/%D2%AE%D0%B5%D0%BB%D1%8D%D1%85_%D1%81%D0%B8%D1%81%D1%82%D0%B5%D0%BC" title="Үелэх систем – Mongolian" lang="mn" hreflang="mn" data-title="Үелэх систем" data-language-autonym="Монгол" data-language-local-name="Mongolian" class="interlanguage-link-target"><span>Монгол</span></a></li><li class="interlanguage-link interwiki-my mw-list-item"><a href="https://my.wikipedia.org/wiki/%E1%80%92%E1%80%BC%E1%80%95%E1%80%BA%E1%80%85%E1%80%84%E1%80%BA%E1%80%A1%E1%80%9C%E1%80%BE%E1%80%8A%E1%80%B7%E1%80%BA%E1%80%80%E1%80%BB%E1%80%87%E1%80%9A%E1%80%AC%E1%80%B8" title="ဒြပ်စင်အလှည့်ကျဇယား – Burmese" lang="my" hreflang="my" data-title="ဒြပ်စင်အလှည့်ကျဇယား" data-language-autonym="မြန်မာဘာသာ" data-language-local-name="Burmese" class="interlanguage-link-target"><span>မြန်မာဘာသာ</span></a></li><li class="interlanguage-link interwiki-nah mw-list-item"><a href="https://nah.wikipedia.org/wiki/Tlap%C4%93uhc%C4%81y%C5%8Dtl_nemachiy%C5%8Dt%C4%ABlp%C4%81ntli" title="Tlapēuhcāyōtl nemachiyōtīlpāntli – Nahuatl" lang="nah" hreflang="nah" data-title="Tlapēuhcāyōtl nemachiyōtīlpāntli" data-language-autonym="Nāhuatl" data-language-local-name="Nahuatl" class="interlanguage-link-target"><span>Nāhuatl</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Periodiek_systeem" title="Periodiek systeem – Dutch" lang="nl" hreflang="nl" data-title="Periodiek systeem" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ne mw-list-item"><a href="https://ne.wikipedia.org/wiki/%E0%A4%86%E0%A4%B5%E0%A4%B0%E0%A5%8D%E0%A4%A4_%E0%A4%B8%E0%A4%BE%E0%A4%B0%E0%A4%A3%E0%A5%80" title="आवर्त सारणी – Nepali" lang="ne" hreflang="ne" data-title="आवर्त सारणी" data-language-autonym="नेपाली" data-language-local-name="Nepali" class="interlanguage-link-target"><span>नेपाली</span></a></li><li class="interlanguage-link interwiki-new mw-list-item"><a href="https://new.wikipedia.org/wiki/%E0%A4%A4%E0%A4%A4%E0%A5%8D%E0%A4%A4%E0%A5%8D%E0%A4%B5%E0%A4%AE%E0%A4%BE%E0%A4%82" title="तत्त्वमां – Newari" lang="new" hreflang="new" data-title="तत्त्वमां" data-language-autonym="नेपाल भाषा" data-language-local-name="Newari" class="interlanguage-link-target"><span>नेपाल भाषा</span></a></li><li class="interlanguage-link interwiki-ja badge-Q17437798 badge-goodarticle mw-list-item" title="good article badge"><a href="https://ja.wikipedia.org/wiki/%E5%91%A8%E6%9C%9F%E8%A1%A8" title="周期表 – Japanese" lang="ja" hreflang="ja" data-title="周期表" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-ce mw-list-item"><a href="https://ce.wikipedia.org/wiki/%D0%A5%D0%B8%D0%BC%D0%B8%D0%BD_%D1%85%D3%80%D1%83%D0%BC%D0%B0%D0%BB%D0%B3%D0%B8%D0%B9%D0%BD_%D1%80%D0%BE%D0%B3%D3%80%D0%B0%D0%BB%D0%BB%D0%B8%D0%BD_%D1%81%D0%B8%D1%81%D1%82%D0%B5%D0%BC%D0%B0" title="Химин хӀумалгийн рогӀаллин система – Chechen" lang="ce" hreflang="ce" data-title="Химин хӀумалгийн рогӀаллин система" data-language-autonym="Нохчийн" data-language-local-name="Chechen" class="interlanguage-link-target"><span>Нохчийн</span></a></li><li class="interlanguage-link interwiki-frr badge-Q17437798 badge-goodarticle mw-list-item" title="good article badge"><a href="https://frr.wikipedia.org/wiki/Perioodisch_tab%C3%A4le" title="Perioodisch tabäle – Northern Frisian" lang="frr" hreflang="frr" data-title="Perioodisch tabäle" data-language-autonym="Nordfriisk" data-language-local-name="Northern Frisian" class="interlanguage-link-target"><span>Nordfriisk</span></a></li><li class="interlanguage-link interwiki-no badge-Q17506997 badge-featuredlist mw-list-item" title="featured list badge"><a href="https://no.wikipedia.org/wiki/Periodesystemet" title="Periodesystemet – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Periodesystemet" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/Periodesystemet" title="Periodesystemet – Norwegian Nynorsk" lang="nn" hreflang="nn" data-title="Periodesystemet" data-language-autonym="Norsk nynorsk" data-language-local-name="Norwegian Nynorsk" class="interlanguage-link-target"><span>Norsk nynorsk</span></a></li><li class="interlanguage-link interwiki-oc mw-list-item"><a href="https://oc.wikipedia.org/wiki/Taula_periodica" title="Taula periodica – Occitan" lang="oc" hreflang="oc" data-title="Taula periodica" data-language-autonym="Occitan" data-language-local-name="Occitan" class="interlanguage-link-target"><span>Occitan</span></a></li><li class="interlanguage-link interwiki-mhr mw-list-item"><a href="https://mhr.wikipedia.org/wiki/%D0%A5%D0%B8%D0%BC%D0%B8%D0%B9_%D1%82%D3%B1%D2%A5%D0%BB%D1%8B%D0%BA-%D0%B2%D0%BB%D0%B0%D0%BA%D1%8B%D0%BD_%D0%BF%D0%B5%D1%80%D0%B8%D0%BE%D0%B4%D0%B8%D0%BA_%D1%80%D0%B0%D0%B4%D0%B0%D0%BC%D0%BB%D1%8B%D0%BA%D1%88%D0%B5" title="Химий тӱҥлык-влакын периодик радамлыкше – Eastern Mari" lang="mhr" hreflang="mhr" data-title="Химий тӱҥлык-влакын периодик радамлыкше" data-language-autonym="Олык марий" data-language-local-name="Eastern Mari" class="interlanguage-link-target"><span>Олык марий</span></a></li><li class="interlanguage-link interwiki-or mw-list-item"><a href="https://or.wikipedia.org/wiki/%E0%AC%AA%E0%AC%B0%E0%AD%8D%E0%AC%AF%E0%AD%8D%E0%AD%9F%E0%AC%BE%E0%AD%9F_%E0%AC%B8%E0%AC%BE%E0%AC%B0%E0%AC%A3%E0%AD%80" title="ପର୍ଯ୍ୟାୟ ସାରଣୀ – Odia" lang="or" hreflang="or" data-title="ପର୍ଯ୍ୟାୟ ସାରଣୀ" data-language-autonym="ଓଡ଼ିଆ" data-language-local-name="Odia" class="interlanguage-link-target"><span>ଓଡ଼ିଆ</span></a></li><li class="interlanguage-link interwiki-om mw-list-item"><a href="https://om.wikipedia.org/wiki/Gabatee_Wahiyyoolee" title="Gabatee Wahiyyoolee – Oromo" lang="om" hreflang="om" data-title="Gabatee Wahiyyoolee" data-language-autonym="Oromoo" data-language-local-name="Oromo" class="interlanguage-link-target"><span>Oromoo</span></a></li><li class="interlanguage-link interwiki-uz mw-list-item"><a href="https://uz.wikipedia.org/wiki/Kimyoviy_elementlar_davriy_sistemasi" title="Kimyoviy elementlar davriy sistemasi – Uzbek" lang="uz" hreflang="uz" data-title="Kimyoviy elementlar davriy sistemasi" data-language-autonym="Oʻzbekcha / ўзбекча" data-language-local-name="Uzbek" class="interlanguage-link-target"><span>Oʻzbekcha / ўзбекча</span></a></li><li class="interlanguage-link interwiki-pa mw-list-item"><a href="https://pa.wikipedia.org/wiki/%E0%A8%AE%E0%A8%BF%E0%A8%86%E0%A8%A6%E0%A9%80_%E0%A8%AA%E0%A8%B9%E0%A8%BE%E0%A9%9C%E0%A8%BE" title="ਮਿਆਦੀ ਪਹਾੜਾ – Punjabi" lang="pa" hreflang="pa" data-title="ਮਿਆਦੀ ਪਹਾੜਾ" data-language-autonym="ਪੰਜਾਬੀ" data-language-local-name="Punjabi" class="interlanguage-link-target"><span>ਪੰਜਾਬੀ</span></a></li><li class="interlanguage-link interwiki-pnb mw-list-item"><a href="https://pnb.wikipedia.org/wiki/%D9%BE%DB%8C%D8%B1%DB%8C%D8%A7%DA%88%DA%A9_%D9%B9%DB%8C%D8%A8%D9%84" title="پیریاڈک ٹیبل – Western Punjabi" lang="pnb" hreflang="pnb" data-title="پیریاڈک ٹیبل" data-language-autonym="پنجابی" data-language-local-name="Western Punjabi" class="interlanguage-link-target"><span>پنجابی</span></a></li><li class="interlanguage-link interwiki-blk mw-list-item"><a href="https://blk.wikipedia.org/wiki/%E1%80%A1%E1%80%91%E1%80%B2%E1%80%B7%E1%80%9B%E1%80%B1%E1%80%AC%E1%80%B7%EA%A9%BB_%E1%80%91%E1%80%AC%EA%A9%BB%E1%80%9B%E1%80%BD%E1%80%B1%E1%80%AC%E1%80%84%E1%80%BA" title="အထဲ့ရော့ꩻ ထာꩻရွောင် – Pa'O" lang="blk" hreflang="blk" data-title="အထဲ့ရော့ꩻ ထာꩻရွောင်" data-language-autonym="ပအိုဝ်ႏဘာႏသာႏ" data-language-local-name="Pa'O" class="interlanguage-link-target"><span>ပအိုဝ်ႏဘာႏသာႏ</span></a></li><li class="interlanguage-link interwiki-pap mw-list-item"><a href="https://pap.wikipedia.org/wiki/Tab%C3%A8l_peri%C3%B3diko" title="Tabèl periódiko – Papiamento" lang="pap" hreflang="pap" data-title="Tabèl periódiko" data-language-autonym="Papiamentu" data-language-local-name="Papiamento" class="interlanguage-link-target"><span>Papiamentu</span></a></li><li class="interlanguage-link interwiki-ps mw-list-item"><a href="https://ps.wikipedia.org/wiki/%D8%AF%D8%B9%D9%86%D8%A7%D8%B5%D8%B1%D9%88_%D8%AF%D9%88%D8%B1%D8%A7%D9%86%D9%8A_%D8%AC%D8%AF%D9%88%D9%84" title="دعناصرو دوراني جدول – Pashto" lang="ps" hreflang="ps" data-title="دعناصرو دوراني جدول" data-language-autonym="پښتو" data-language-local-name="Pashto" class="interlanguage-link-target"><span>پښتو</span></a></li><li class="interlanguage-link interwiki-jam mw-list-item"><a href="https://jam.wikipedia.org/wiki/Piiriadik_tiebl" title="Piiriadik tiebl – Jamaican Creole English" lang="jam" hreflang="jam" data-title="Piiriadik tiebl" data-language-autonym="Patois" data-language-local-name="Jamaican Creole English" class="interlanguage-link-target"><span>Patois</span></a></li><li class="interlanguage-link interwiki-koi mw-list-item"><a href="https://koi.wikipedia.org/wiki/%D0%9F%D0%B5%D1%80%D0%B8%D0%BE%D0%B4%D0%B4%D1%8D%D0%B7_%D1%81%D1%8C%D3%A7%D1%80%D1%82%D1%96_%D1%85%D0%B8%D0%BC%D0%B8%D1%8F_%D3%A7%D1%82%D1%83%D0%B2%D1%82%D0%BE%D1%80%D1%80%D0%B5%D0%B7%D0%BB%D3%A7%D0%BD_%D1%82%D1%8D%D1%87%D0%B0%D1%81" title="Периоддэз сьӧрті химия ӧтувторрезлӧн тэчас – Komi-Permyak" lang="koi" hreflang="koi" data-title="Периоддэз сьӧрті химия ӧтувторрезлӧн тэчас" data-language-autonym="Перем коми" data-language-local-name="Komi-Permyak" class="interlanguage-link-target"><span>Перем коми</span></a></li><li class="interlanguage-link interwiki-km mw-list-item"><a href="https://km.wikipedia.org/wiki/%E1%9E%8F%E1%9E%B6%E1%9E%9A%E1%9E%B6%E1%9E%84%E1%9E%81%E1%9E%BD%E1%9E%94%E1%9E%93%E1%9F%83%E1%9E%92%E1%9E%B6%E1%9E%8F%E1%9E%BB%E1%9E%82%E1%9E%B8%E1%9E%98%E1%9E%B8" title="តារាងខួបនៃធាតុគីមី – Khmer" lang="km" hreflang="km" data-title="តារាងខួបនៃធាតុគីមី" data-language-autonym="ភាសាខ្មែរ" data-language-local-name="Khmer" class="interlanguage-link-target"><span>ភាសាខ្មែរ</span></a></li><li class="interlanguage-link interwiki-pcd mw-list-item"><a href="https://pcd.wikipedia.org/wiki/Tableau_p%C3%A9riodique" title="Tableau périodique – Picard" lang="pcd" hreflang="pcd" data-title="Tableau périodique" data-language-autonym="Picard" data-language-local-name="Picard" class="interlanguage-link-target"><span>Picard</span></a></li><li class="interlanguage-link interwiki-pms mw-list-item"><a href="https://pms.wikipedia.org/wiki/T%C3%A0ula_peri%C3%B2dica" title="Tàula periòdica – Piedmontese" lang="pms" hreflang="pms" data-title="Tàula periòdica" data-language-autonym="Piemontèis" data-language-local-name="Piedmontese" class="interlanguage-link-target"><span>Piemontèis</span></a></li><li class="interlanguage-link interwiki-tpi mw-list-item"><a href="https://tpi.wikipedia.org/wiki/Tebol_bilong_ol_elemen" title="Tebol bilong ol elemen – Tok Pisin" lang="tpi" hreflang="tpi" data-title="Tebol bilong ol elemen" data-language-autonym="Tok Pisin" data-language-local-name="Tok Pisin" class="interlanguage-link-target"><span>Tok Pisin</span></a></li><li class="interlanguage-link interwiki-nds mw-list-item"><a href="https://nds.wikipedia.org/wiki/Periodensystem" title="Periodensystem – Low German" lang="nds" hreflang="nds" data-title="Periodensystem" data-language-autonym="Plattdüütsch" data-language-local-name="Low German" class="interlanguage-link-target"><span>Plattdüütsch</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Uk%C5%82ad_okresowy_pierwiastk%C3%B3w" title="Układ okresowy pierwiastków – Polish" lang="pl" hreflang="pl" data-title="Układ okresowy pierwiastków" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pnt mw-list-item"><a href="https://pnt.wikipedia.org/wiki/%CE%A0%CE%B5%CF%81%CE%B9%CE%BF%CE%B4%CE%B9%CE%BA%CF%8C%CE%BD_%CE%A0%CE%B9%CE%BD%CE%AC%CE%BA%CE%B9%CE%BD" title="Περιοδικόν Πινάκιν – Pontic" lang="pnt" hreflang="pnt" data-title="Περιοδικόν Πινάκιν" data-language-autonym="Ποντιακά" data-language-local-name="Pontic" class="interlanguage-link-target"><span>Ποντιακά</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Tabela_peri%C3%B3dica" title="Tabela periódica – Portuguese" lang="pt" hreflang="pt" data-title="Tabela periódica" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/Tabelul_periodic_al_elementelor" title="Tabelul periodic al elementelor – Romanian" lang="ro" hreflang="ro" data-title="Tabelul periodic al elementelor" data-language-autonym="Română" data-language-local-name="Romanian" class="interlanguage-link-target"><span>Română</span></a></li><li class="interlanguage-link interwiki-qu mw-list-item"><a href="https://qu.wikipedia.org/wiki/Qallawap_%C3%B1iqi_rakirinkuna" title="Qallawap ñiqi rakirinkuna – Quechua" lang="qu" hreflang="qu" data-title="Qallawap ñiqi rakirinkuna" data-language-autonym="Runa Simi" data-language-local-name="Quechua" class="interlanguage-link-target"><span>Runa Simi</span></a></li><li class="interlanguage-link interwiki-rue mw-list-item"><a href="https://rue.wikipedia.org/wiki/%D0%9F%D0%B5%D1%80%D1%96%D0%BE%D0%B4%D1%96%D1%87%D0%BD%D0%B0_%D1%81%D1%96%D1%81%D1%82%D0%B5%D0%BC%D0%B0_%D0%B5%D0%BB%D0%B5%D0%BC%D0%B5%D0%BD%D1%82%D1%96%D0%B2" title="Періодічна сістема елементів – Rusyn" lang="rue" hreflang="rue" data-title="Періодічна сістема елементів" data-language-autonym="Русиньскый" data-language-local-name="Rusyn" class="interlanguage-link-target"><span>Русиньскый</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%9F%D0%B5%D1%80%D0%B8%D0%BE%D0%B4%D0%B8%D1%87%D0%B5%D1%81%D0%BA%D0%B0%D1%8F_%D1%81%D0%B8%D1%81%D1%82%D0%B5%D0%BC%D0%B0_%D1%85%D0%B8%D0%BC%D0%B8%D1%87%D0%B5%D1%81%D0%BA%D0%B8%D1%85_%D1%8D%D0%BB%D0%B5%D0%BC%D0%B5%D0%BD%D1%82%D0%BE%D0%B2" title="Периодическая система химических элементов – Russian" lang="ru" hreflang="ru" data-title="Периодическая система химических элементов" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sah mw-list-item"><a href="https://sah.wikipedia.org/wiki/%D0%9F%D0%B5%D1%80%D0%B8%D0%BE%D0%B4%D1%82%D0%B0%D0%B0%D1%85_%D1%82%D0%B0%D0%B0%D0%B1%D1%8B%D0%BB" title="Периодтаах таабыл – Yakut" lang="sah" hreflang="sah" data-title="Периодтаах таабыл" data-language-autonym="Саха тыла" data-language-local-name="Yakut" class="interlanguage-link-target"><span>Саха тыла</span></a></li><li class="interlanguage-link interwiki-sa mw-list-item"><a href="https://sa.wikipedia.org/wiki/%E0%A4%86%E0%A4%B5%E0%A4%B0%E0%A5%8D%E0%A4%A4%E0%A4%B8%E0%A4%BE%E0%A4%B0%E0%A4%A3%E0%A5%80" title="आवर्तसारणी – Sanskrit" lang="sa" hreflang="sa" data-title="आवर्तसारणी" data-language-autonym="संस्कृतम्" data-language-local-name="Sanskrit" class="interlanguage-link-target"><span>संस्कृतम्</span></a></li><li class="interlanguage-link interwiki-sc mw-list-item"><a href="https://sc.wikipedia.org/wiki/T%C3%A0ula_peri%C3%B2dica_de_is_elementos" title="Tàula periòdica de is elementos – Sardinian" lang="sc" hreflang="sc" data-title="Tàula periòdica de is elementos" data-language-autonym="Sardu" data-language-local-name="Sardinian" class="interlanguage-link-target"><span>Sardu</span></a></li><li class="interlanguage-link interwiki-sco mw-list-item"><a href="https://sco.wikipedia.org/wiki/Periodic_cairt" title="Periodic cairt – Scots" lang="sco" hreflang="sco" data-title="Periodic cairt" data-language-autonym="Scots" data-language-local-name="Scots" class="interlanguage-link-target"><span>Scots</span></a></li><li class="interlanguage-link interwiki-stq mw-list-item"><a href="https://stq.wikipedia.org/wiki/Periodiske_Tabelle" title="Periodiske Tabelle – Saterland Frisian" lang="stq" hreflang="stq" data-title="Periodiske Tabelle" data-language-autonym="Seeltersk" data-language-local-name="Saterland Frisian" class="interlanguage-link-target"><span>Seeltersk</span></a></li><li class="interlanguage-link interwiki-st mw-list-item"><a href="https://st.wikipedia.org/wiki/Tafole_ya_periodiki" title="Tafole ya periodiki – Southern Sotho" lang="st" hreflang="st" data-title="Tafole ya periodiki" data-language-autonym="Sesotho" data-language-local-name="Southern Sotho" class="interlanguage-link-target"><span>Sesotho</span></a></li><li class="interlanguage-link interwiki-sq mw-list-item"><a href="https://sq.wikipedia.org/wiki/Sistemi_periodik_i_elementeve" title="Sistemi periodik i elementeve – Albanian" lang="sq" hreflang="sq" data-title="Sistemi periodik i elementeve" data-language-autonym="Shqip" data-language-local-name="Albanian" class="interlanguage-link-target"><span>Shqip</span></a></li><li class="interlanguage-link interwiki-scn mw-list-item"><a href="https://scn.wikipedia.org/wiki/T%C3%A0vula_piri%C3%B2dica" title="Tàvula piriòdica – Sicilian" lang="scn" hreflang="scn" data-title="Tàvula piriòdica" data-language-autonym="Sicilianu" data-language-local-name="Sicilian" class="interlanguage-link-target"><span>Sicilianu</span></a></li><li class="interlanguage-link interwiki-si mw-list-item"><a href="https://si.wikipedia.org/wiki/%E0%B6%86%E0%B7%80%E0%B6%BB%E0%B7%8A%E0%B6%AD%E0%B7%92%E0%B6%AD%E0%B7%8F_%E0%B7%80%E0%B6%9C%E0%B7%94%E0%B7%80" title="ආවර්තිතා වගුව – Sinhala" lang="si" hreflang="si" data-title="ආවර්තිතා වගුව" data-language-autonym="සිංහල" data-language-local-name="Sinhala" class="interlanguage-link-target"><span>සිංහල</span></a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/Periodic_table" title="Periodic table – Simple English" lang="en-simple" hreflang="en-simple" data-title="Periodic table" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target"><span>Simple English</span></a></li><li class="interlanguage-link interwiki-sd mw-list-item"><a href="https://sd.wikipedia.org/wiki/%D8%AF%D9%88%D8%B1%D9%8A_%D8%AC%D8%AF%D9%88%D9%84" title="دوري جدول – Sindhi" lang="sd" hreflang="sd" data-title="دوري جدول" data-language-autonym="سنڌي" data-language-local-name="Sindhi" class="interlanguage-link-target"><span>سنڌي</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Periodick%C3%A1_tabu%C4%BEka" title="Periodická tabuľka – Slovak" lang="sk" hreflang="sk" data-title="Periodická tabuľka" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/Periodni_sistem_elementov" title="Periodni sistem elementov – Slovenian" lang="sl" hreflang="sl" data-title="Periodni sistem elementov" data-language-autonym="Slovenščina" data-language-local-name="Slovenian" class="interlanguage-link-target"><span>Slovenščina</span></a></li><li class="interlanguage-link interwiki-szl mw-list-item"><a href="https://szl.wikipedia.org/wiki/Uk%C5%82%C5%8Fd_%C3%B4kresowy_elymynt%C5%8Dw" title="Ukłŏd ôkresowy elymyntōw – Silesian" lang="szl" hreflang="szl" data-title="Ukłŏd ôkresowy elymyntōw" data-language-autonym="Ślůnski" data-language-local-name="Silesian" class="interlanguage-link-target"><span>Ślůnski</span></a></li><li class="interlanguage-link interwiki-so mw-list-item"><a href="https://so.wikipedia.org/wiki/Jadwalka_Curiyayaasha" title="Jadwalka Curiyayaasha – Somali" lang="so" hreflang="so" data-title="Jadwalka Curiyayaasha" data-language-autonym="Soomaaliga" data-language-local-name="Somali" class="interlanguage-link-target"><span>Soomaaliga</span></a></li><li class="interlanguage-link interwiki-ckb mw-list-item"><a href="https://ckb.wikipedia.org/wiki/%D8%AE%D8%B4%D8%AA%DB%95%DB%8C_%D8%AE%D9%88%D9%84%DB%8C" title="خشتەی خولی – Central Kurdish" lang="ckb" hreflang="ckb" data-title="خشتەی خولی" data-language-autonym="کوردی" data-language-local-name="Central Kurdish" class="interlanguage-link-target"><span>کوردی</span></a></li><li class="interlanguage-link interwiki-srn mw-list-item"><a href="https://srn.wikipedia.org/wiki/Periodiki_sistemi" title="Periodiki sistemi – Sranan Tongo" lang="srn" hreflang="srn" data-title="Periodiki sistemi" data-language-autonym="Sranantongo" data-language-local-name="Sranan Tongo" class="interlanguage-link-target"><span>Sranantongo</span></a></li><li class="interlanguage-link interwiki-sr badge-Q17437796 badge-featuredarticle mw-list-item" title="featured article badge"><a href="https://sr.wikipedia.org/wiki/%D0%9F%D0%B5%D1%80%D0%B8%D0%BE%D0%B4%D0%BD%D0%B8_%D1%81%D0%B8%D1%81%D1%82%D0%B5%D0%BC" title="Периодни систем – Serbian" lang="sr" hreflang="sr" data-title="Периодни систем" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-sh mw-list-item"><a href="https://sh.wikipedia.org/wiki/Periodni_sistem_elemenata" title="Periodni sistem elemenata – Serbo-Croatian" lang="sh" hreflang="sh" data-title="Periodni sistem elemenata" data-language-autonym="Srpskohrvatski / српскохрватски" data-language-local-name="Serbo-Croatian" class="interlanguage-link-target"><span>Srpskohrvatski / српскохрватски</span></a></li><li class="interlanguage-link interwiki-su mw-list-item"><a href="https://su.wikipedia.org/wiki/Tab%C3%A9l_periodik" title="Tabél periodik – Sundanese" lang="su" hreflang="su" data-title="Tabél periodik" data-language-autonym="Sunda" data-language-local-name="Sundanese" class="interlanguage-link-target"><span>Sunda</span></a></li><li class="interlanguage-link interwiki-fi badge-Q17559452 badge-recommendedarticle mw-list-item" title="recommended article"><a href="https://fi.wikipedia.org/wiki/Jaksollinen_j%C3%A4rjestelm%C3%A4" title="Jaksollinen järjestelmä – Finnish" lang="fi" hreflang="fi" data-title="Jaksollinen järjestelmä" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Periodiska_systemet" title="Periodiska systemet – Swedish" lang="sv" hreflang="sv" data-title="Periodiska systemet" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-tl mw-list-item"><a href="https://tl.wikipedia.org/wiki/Talahanayang_peryodiko" title="Talahanayang peryodiko – Tagalog" lang="tl" hreflang="tl" data-title="Talahanayang peryodiko" data-language-autonym="Tagalog" data-language-local-name="Tagalog" class="interlanguage-link-target"><span>Tagalog</span></a></li><li class="interlanguage-link interwiki-ta mw-list-item"><a href="https://ta.wikipedia.org/wiki/%E0%AE%A4%E0%AE%A9%E0%AE%BF%E0%AE%AE_%E0%AE%85%E0%AE%9F%E0%AF%8D%E0%AE%9F%E0%AE%B5%E0%AE%A3%E0%AF%88" title="தனிம அட்டவணை – Tamil" lang="ta" hreflang="ta" data-title="தனிம அட்டவணை" data-language-autonym="தமிழ்" data-language-local-name="Tamil" class="interlanguage-link-target"><span>தமிழ்</span></a></li><li class="interlanguage-link interwiki-shi mw-list-item"><a href="https://shi.wikipedia.org/wiki/Taflwit_tazdawant_n_ifr%E1%B8%8Disn" title="Taflwit tazdawant n ifrḍisn – Tachelhit" lang="shi" hreflang="shi" data-title="Taflwit tazdawant n ifrḍisn" data-language-autonym="Taclḥit" data-language-local-name="Tachelhit" class="interlanguage-link-target"><span>Taclḥit</span></a></li><li class="interlanguage-link interwiki-kab mw-list-item"><a href="https://kab.wikipedia.org/wiki/Tafelwit_tawalant" title="Tafelwit tawalant – Kabyle" lang="kab" hreflang="kab" data-title="Tafelwit tawalant" data-language-autonym="Taqbaylit" data-language-local-name="Kabyle" class="interlanguage-link-target"><span>Taqbaylit</span></a></li><li class="interlanguage-link interwiki-roa-tara mw-list-item"><a href="https://roa-tara.wikipedia.org/wiki/Tavele_Periodiche" title="Tavele Periodiche – Tarantino" lang="nap-x-tara" hreflang="nap-x-tara" data-title="Tavele Periodiche" data-language-autonym="Tarandíne" data-language-local-name="Tarantino" class="interlanguage-link-target"><span>Tarandíne</span></a></li><li class="interlanguage-link interwiki-tt mw-list-item"><a href="https://tt.wikipedia.org/wiki/%D0%9C%D0%B5%D0%BD%D0%B4%D0%B5%D0%BB%D0%B5%D0%B5%D0%B2%D0%BD%D1%8B%D2%A3_%D0%BF%D0%B5%D1%80%D0%B8%D0%BE%D0%B4%D0%B8%D0%BA_%D1%82%D0%B0%D0%B1%D0%BB%D0%B8%D1%86%D0%B0%D1%81%D1%8B" title="Менделеевның периодик таблицасы – Tatar" lang="tt" hreflang="tt" data-title="Менделеевның периодик таблицасы" data-language-autonym="Татарча / tatarça" data-language-local-name="Tatar" class="interlanguage-link-target"><span>Татарча / tatarça</span></a></li><li class="interlanguage-link interwiki-te mw-list-item"><a href="https://te.wikipedia.org/wiki/%E0%B0%86%E0%B0%B5%E0%B0%B0%E0%B1%8D%E0%B0%A4%E0%B0%A8_%E0%B0%AA%E0%B0%9F%E0%B1%8D%E0%B0%9F%E0%B0%BF%E0%B0%95" title="ఆవర్తన పట్టిక – Telugu" lang="te" hreflang="te" data-title="ఆవర్తన పట్టిక" data-language-autonym="తెలుగు" data-language-local-name="Telugu" class="interlanguage-link-target"><span>తెలుగు</span></a></li><li class="interlanguage-link interwiki-th badge-Q17437798 badge-goodarticle mw-list-item" title="good article badge"><a href="https://th.wikipedia.org/wiki/%E0%B8%95%E0%B8%B2%E0%B8%A3%E0%B8%B2%E0%B8%87%E0%B8%98%E0%B8%B2%E0%B8%95%E0%B8%B8" title="ตารางธาตุ – Thai" lang="th" hreflang="th" data-title="ตารางธาตุ" data-language-autonym="ไทย" data-language-local-name="Thai" class="interlanguage-link-target"><span>ไทย</span></a></li><li class="interlanguage-link interwiki-tg mw-list-item"><a href="https://tg.wikipedia.org/wiki/%D2%B6%D0%B0%D0%B4%D0%B2%D0%B0%D0%BB%D0%B8_%D0%B4%D0%B0%D0%B2%D1%80%D0%B8%D0%B8_%D1%83%D0%BD%D1%81%D1%83%D1%80%D2%B3%D0%BE%D0%B8_%D0%BA%D0%B8%D0%BC%D0%B8%D1%91%D3%A3" title="Ҷадвали даврии унсурҳои кимиёӣ – Tajik" lang="tg" hreflang="tg" data-title="Ҷадвали даврии унсурҳои кимиёӣ" data-language-autonym="Тоҷикӣ" data-language-local-name="Tajik" class="interlanguage-link-target"><span>Тоҷикӣ</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Periyodik_tablo" title="Periyodik tablo – Turkish" lang="tr" hreflang="tr" data-title="Periyodik tablo" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-tk mw-list-item"><a href="https://tk.wikipedia.org/wiki/Himiki_elementleri%C5%88_periodik_ulgamy" title="Himiki elementleriň periodik ulgamy – Turkmen" lang="tk" hreflang="tk" data-title="Himiki elementleriň periodik ulgamy" data-language-autonym="Türkmençe" data-language-local-name="Turkmen" class="interlanguage-link-target"><span>Türkmençe</span></a></li><li class="interlanguage-link interwiki-tyv mw-list-item"><a href="https://tyv.wikipedia.org/wiki/%D0%A5%D0%B8%D0%BC%D0%B8%D0%BA%D1%82%D0%B8%D0%B3_%D1%8D%D0%BB%D0%B5%D0%BC%D0%B5%D0%BD%D1%82%D0%B8%D0%BB%D0%B5%D1%80%D0%BD%D0%B8%D2%A3_%D0%BF%D0%B5%D1%80%D0%B8%D0%BE%D0%B4%D1%82%D1%83%D0%B3_%D1%81%D0%B8%D1%81%D1%82%D0%B5%D0%BC%D0%B0%D0%B7%D1%8B" title="Химиктиг элементилерниң периодтуг системазы – Tuvinian" lang="tyv" hreflang="tyv" data-title="Химиктиг элементилерниң периодтуг системазы" data-language-autonym="Тыва дыл" data-language-local-name="Tuvinian" class="interlanguage-link-target"><span>Тыва дыл</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%9F%D0%B5%D1%80%D1%96%D0%BE%D0%B4%D0%B8%D1%87%D0%BD%D0%B0_%D1%81%D0%B8%D1%81%D1%82%D0%B5%D0%BC%D0%B0_%D1%85%D1%96%D0%BC%D1%96%D1%87%D0%BD%D0%B8%D1%85_%D0%B5%D0%BB%D0%B5%D0%BC%D0%B5%D0%BD%D1%82%D1%96%D0%B2" title="Періодична система хімічних елементів – Ukrainian" lang="uk" hreflang="uk" data-title="Періодична система хімічних елементів" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-ur mw-list-item"><a href="https://ur.wikipedia.org/wiki/%D8%AF%D9%88%D8%B1%DB%8C_%D8%AC%D8%AF%D9%88%D9%84" title="دوری جدول – Urdu" lang="ur" hreflang="ur" data-title="دوری جدول" data-language-autonym="اردو" data-language-local-name="Urdu" class="interlanguage-link-target"><span>اردو</span></a></li><li class="interlanguage-link interwiki-ug mw-list-item"><a href="https://ug.wikipedia.org/wiki/%D8%A6%DB%90%D9%84%DB%90%D9%85%DB%90%D9%86%D8%AA%D9%84%D8%A7%D8%B1%D9%86%D9%89%DA%AD_%D8%AF%DB%95%DB%8B%D8%B1%D9%89%D9%8A_%D8%AC%DB%95%DB%95%D8%AF%DB%8B%D9%89%D9%84%D9%89" title="ئېلېمېنتلارنىڭ دەۋرىي جەەدۋىلى – Uyghur" lang="ug" hreflang="ug" data-title="ئېلېمېنتلارنىڭ دەۋرىي جەەدۋىلى" data-language-autonym="ئۇيغۇرچە / Uyghurche" data-language-local-name="Uyghur" class="interlanguage-link-target"><span>ئۇيغۇرچە / Uyghurche</span></a></li><li class="interlanguage-link interwiki-za mw-list-item"><a href="https://za.wikipedia.org/wiki/Yenzsoq_Couhgibyauj" title="Yenzsoq Couhgibyauj – Zhuang" lang="za" hreflang="za" data-title="Yenzsoq Couhgibyauj" data-language-autonym="Vahcuengh" data-language-local-name="Zhuang" class="interlanguage-link-target"><span>Vahcuengh</span></a></li><li class="interlanguage-link interwiki-vec mw-list-item"><a href="https://vec.wikipedia.org/wiki/Tabe%C5%82a_peri%C3%B2dega" title="Tabeła periòdega – Venetian" lang="vec" hreflang="vec" data-title="Tabeła periòdega" data-language-autonym="Vèneto" data-language-local-name="Venetian" class="interlanguage-link-target"><span>Vèneto</span></a></li><li class="interlanguage-link interwiki-vep mw-list-item"><a href="https://vep.wikipedia.org/wiki/Himi%C5%BEiden_elementoiden_periodine_tablut" title="Himižiden elementoiden periodine tablut – Veps" lang="vep" hreflang="vep" data-title="Himižiden elementoiden periodine tablut" data-language-autonym="Vepsän kel’" data-language-local-name="Veps" class="interlanguage-link-target"><span>Vepsän kel’</span></a></li><li class="interlanguage-link interwiki-vi badge-Q17437796 badge-featuredarticle mw-list-item" title="featured article badge"><a href="https://vi.wikipedia.org/wiki/B%E1%BA%A3ng_tu%E1%BA%A7n_ho%C3%A0n" title="Bảng tuần hoàn – Vietnamese" lang="vi" hreflang="vi" data-title="Bảng tuần hoàn" data-language-autonym="Tiếng Việt" data-language-local-name="Vietnamese" class="interlanguage-link-target"><span>Tiếng Việt</span></a></li><li class="interlanguage-link interwiki-fiu-vro mw-list-item"><a href="https://fiu-vro.wikipedia.org/wiki/Mendelejevi_tap%C3%B5l" title="Mendelejevi tapõl – Võro" lang="vro" hreflang="vro" data-title="Mendelejevi tapõl" data-language-autonym="Võro" data-language-local-name="Võro" class="interlanguage-link-target"><span>Võro</span></a></li><li class="interlanguage-link interwiki-wa mw-list-item"><a href="https://wa.wikipedia.org/wiki/T%C3%A5vlea_periodike_des_elemints" title="Tåvlea periodike des elemints – Walloon" lang="wa" hreflang="wa" data-title="Tåvlea periodike des elemints" data-language-autonym="Walon" data-language-local-name="Walloon" class="interlanguage-link-target"><span>Walon</span></a></li><li class="interlanguage-link interwiki-zh-classical mw-list-item"><a href="https://zh-classical.wikipedia.org/wiki/%E5%85%83%E7%B4%A0%E9%80%B1%E6%9C%9F%E8%A1%A8" title="元素週期表 – Literary Chinese" lang="lzh" hreflang="lzh" data-title="元素週期表" data-language-autonym="文言" data-language-local-name="Literary Chinese" class="interlanguage-link-target"><span>文言</span></a></li><li class="interlanguage-link interwiki-vls mw-list-item"><a href="https://vls.wikipedia.org/wiki/Periodiek_syst%C3%A8me" title="Periodiek système – West Flemish" lang="vls" hreflang="vls" data-title="Periodiek système" data-language-autonym="West-Vlams" data-language-local-name="West Flemish" class="interlanguage-link-target"><span>West-Vlams</span></a></li><li class="interlanguage-link interwiki-war mw-list-item"><a href="https://war.wikipedia.org/wiki/Taramdan_peryodika" title="Taramdan peryodika – Waray" lang="war" hreflang="war" data-title="Taramdan peryodika" data-language-autonym="Winaray" data-language-local-name="Waray" class="interlanguage-link-target"><span>Winaray</span></a></li><li class="interlanguage-link interwiki-wuu mw-list-item"><a href="https://wuu.wikipedia.org/wiki/%E5%85%83%E7%B4%A0%E5%91%A8%E6%9C%9F%E8%A1%A8" title="元素周期表 – Wu" lang="wuu" hreflang="wuu" data-title="元素周期表" data-language-autonym="吴语" data-language-local-name="Wu" class="interlanguage-link-target"><span>吴语</span></a></li><li class="interlanguage-link interwiki-yi mw-list-item"><a href="https://yi.wikipedia.org/wiki/%D7%A4%D7%A2%D7%A8%D7%99%D7%90%D7%93%D7%99%D7%A9%D7%A2_%D7%98%D7%90%D7%91%D7%A2%D7%9C%D7%A2" title="פעריאדישע טאבעלע – Yiddish" lang="yi" hreflang="yi" data-title="פעריאדישע טאבעלע" data-language-autonym="ייִדיש" data-language-local-name="Yiddish" class="interlanguage-link-target"><span>ייִדיש</span></a></li><li class="interlanguage-link interwiki-yo mw-list-item"><a href="https://yo.wikipedia.org/wiki/T%C3%A1b%C3%ACl%C3%AC_%C3%A0y%C3%A8_%C3%A0w%E1%BB%8Dn_%E1%BA%B9%CC%81l%C3%ADm%E1%BA%B9%CC%80nt%C3%AC" title="Tábìlì àyè àwọn ẹ́límẹ̀ntì – Yoruba" lang="yo" hreflang="yo" data-title="Tábìlì àyè àwọn ẹ́límẹ̀ntì" data-language-autonym="Yorùbá" data-language-local-name="Yoruba" class="interlanguage-link-target"><span>Yorùbá</span></a></li><li class="interlanguage-link interwiki-zh-yue mw-list-item"><a href="https://zh-yue.wikipedia.org/wiki/%E5%85%83%E7%B4%A0%E9%80%B1%E6%9C%9F%E8%A1%A8" title="元素週期表 – Cantonese" lang="yue" hreflang="yue" data-title="元素週期表" data-language-autonym="粵語" data-language-local-name="Cantonese" class="interlanguage-link-target"><span>粵語</span></a></li><li class="interlanguage-link interwiki-diq mw-list-item"><a href="https://diq.wikipedia.org/wiki/Tabloyo_periyodik" title="Tabloyo periyodik – Zazaki" lang="diq" hreflang="diq" data-title="Tabloyo periyodik" data-language-autonym="Zazaki" data-language-local-name="Zazaki" class="interlanguage-link-target"><span>Zazaki</span></a></li><li class="interlanguage-link interwiki-bat-smg mw-list-item"><a href="https://bat-smg.wikipedia.org/wiki/Mendeliej%C4%97va_kem%C4%97niu_elementu_lental%C4%97" title="Mendeliejėva kemėniu elementu lentalė – Samogitian" lang="sgs" hreflang="sgs" data-title="Mendeliejėva kemėniu elementu lentalė" data-language-autonym="Žemaitėška" data-language-local-name="Samogitian" class="interlanguage-link-target"><span>Žemaitėška</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E5%85%83%E7%B4%A0%E5%91%A8%E6%9C%9F%E8%A1%A8" title="元素周期表 – Chinese" lang="zh" hreflang="zh" data-title="元素周期表" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q10693#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit links</a></span></div> </div> </div> </div> </header> <div class="vector-page-toolbar"> <div class="vector-page-toolbar-container"> <div id="left-navigation"> <nav aria-label="Namespaces"> <div id="p-associated-pages" 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id="mw-indicator-featured-star" class="mw-indicator"><div class="mw-parser-output"><span typeof="mw:File"><a href="/wiki/Wikipedia:Featured_articles*" title="This is a featured article. 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For other uses, see <a href="/wiki/Periodic_table_(disambiguation)" class="mw-disambig" title="Periodic table (disambiguation)">Periodic table (disambiguation)</a>.</div> <p class="mw-empty-elt"> </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Colour_18-col_PT_with_labels.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/8/89/Colour_18-col_PT_with_labels.png/480px-Colour_18-col_PT_with_labels.png" decoding="async" width="480" height="281" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/89/Colour_18-col_PT_with_labels.png/720px-Colour_18-col_PT_with_labels.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/89/Colour_18-col_PT_with_labels.png/960px-Colour_18-col_PT_with_labels.png 2x" data-file-width="2576" data-file-height="1506" /></a><figcaption>Periodic table of the chemical elements showing the most or more commonly named <a href="/wiki/Names_for_sets_of_chemical_elements" title="Names for sets of chemical elements">sets of elements</a> (in periodic tables), and a traditional <a href="/wiki/Dividing_line_between_metals_and_nonmetals" title="Dividing line between metals and nonmetals">dividing line between metals and nonmetals</a>. The <a href="/wiki/Block_(periodic_table)#f-block" title="Block (periodic table)">f-block</a> actually fits between <a href="/wiki/Alkaline_earth_metals" class="mw-redirect" title="Alkaline earth metals">groups 2</a> and <a href="/wiki/Scandium_group" class="mw-redirect" title="Scandium group">3</a>; it is usually shown at the foot of the table to save horizontal space.</figcaption></figure> <style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl ol,.mw-parser-output .hlist dl ul,.mw-parser-output .hlist ol dl,.mw-parser-output .hlist ol ol,.mw-parser-output .hlist ol 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.sidebar-title-with-pretitle a{color:var(--color-progressive)!important}}@media print{body.ns-0 .mw-parser-output .sidebar{display:none!important}}</style><table class="sidebar sidebar-collapse nomobile nowraplinks hlist"><tbody><tr><td class="sidebar-pretitle">Part of <a href="/wiki/Category:Periodic_table" title="Category:Periodic table">a series</a> on the</td></tr><tr><th class="sidebar-title-with-pretitle"><a class="mw-selflink selflink">Periodic table</a></th></tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="border-top:1px solid #aaa;;color: var(--color-base)">Periodic table forms</div><div class="sidebar-list-content mw-collapsible-content"> <ul><li><a class="mw-selflink-fragment" href="#Detailed_table">18-column</a></li> <li><a class="mw-selflink-fragment" href="#The_long-_or_32-column_table">32-column</a></li></ul> <div style="clear:both;" class=""></div> <ul><li><a href="/wiki/Types_of_periodic_tables" title="Types of periodic tables">Alternative</a><span class="nowrap"> </span>and<span class="nowrap"> </span><a href="/wiki/Extended_periodic_table" title="Extended periodic table">extended</a><span class="nowrap"> </span>forms</li></ul></div></div></td> </tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="border-top:1px solid #aaa;;color: var(--color-base)"><a href="/wiki/History_of_the_periodic_table" title="History of the periodic table">Periodic table history</a></div><div class="sidebar-list-content mw-collapsible-content"> <ul><li><a href="/wiki/Dmitri_Mendeleev" title="Dmitri Mendeleev">D. Mendeleev</a> <ul><li><a href="/wiki/Dmitri_Mendeleev#Periodic_table" title="Dmitri Mendeleev">1871 table</a></li> <li><a href="/wiki/Mendeleev%27s_predicted_elements" title="Mendeleev's predicted elements">1869 predictions</a></li></ul></li></ul> <div style="clear:both;" class=""></div> <ul><li><a href="/wiki/Discovery_of_chemical_elements" title="Discovery of chemical elements">Discovery of elements</a></li></ul> <div style="clear:both;" class=""></div> <ul><li><b><a href="/wiki/Naming_of_chemical_elements" title="Naming of chemical elements">Naming</a> and <a href="/wiki/List_of_chemical_element_name_etymologies" title="List of chemical element name etymologies">etymology</a></b></li></ul> <div style="clear:both;" class=""></div> <ul><li><ul><li><a href="/wiki/List_of_chemical_elements_named_after_people" title="List of chemical elements named after people">for people</a></li> <li><a href="/wiki/List_of_chemical_elements_named_after_places" title="List of chemical elements named after places">for places</a></li> <li><a href="/wiki/List_of_chemical_element_naming_controversies" title="List of chemical element naming controversies">controversies</a></li></ul></li></ul> <div style="clear:both;" class=""></div> <ul><li>(<a href="/wiki/Chemical_elements_in_East_Asian_languages" title="Chemical elements in East Asian languages">in East Asia</a>)</li></ul> <div style="clear:both;" class=""></div> <ul><li><a href="/wiki/Systematic_element_name" title="Systematic element name">Systematic element names</a></li></ul></div></div></td> </tr><tr><td class="sidebar-content" style="border-top:1px solid #aaa; text-align:left; background:#eeeeff;"> <div class="center" style="width:auto; margin-left:auto; margin-right:auto;"><b><a href="/wiki/Names_for_sets_of_chemical_elements" title="Names for sets of chemical elements">Sets of elements</a></b></div></td> </tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="border-top:1px solid #aaa;;color: var(--color-base)">By periodic table structure</div><div class="sidebar-list-content mw-collapsible-content"> <ul><li><b><a href="/wiki/Group_(periodic_table)" title="Group (periodic table)">Groups</a> (1–18)</b></li></ul> <div style="clear:both;" class=""></div> <ul><li><a href="/wiki/Group_1_element" class="mw-redirect" title="Group 1 element"><span title="Group 1 — hydrogen group, all s¹ elements">1</span></a> (<a href="/wiki/Alkali_metal" title="Alkali metal"><span title="Part of group 1: Li, Na, K, Rb, Cs, Fr — lithium family, s¹ metals" class="nowrap"><i>alkali metals</i></span></a>)</li> <li><a href="/wiki/Alkaline_earth_metal" title="Alkaline earth metal"><span title="Group 2: Be, Mg, Ca, Sr, Ba, Ra — beryllium group, s² metals" class="nowrap">2 <i>(alkaline earth metals)</i></span></a></li> <li><a href="/wiki/Group_3_element" title="Group 3 element"><span title="Group 3: Sc, Y… — scandium group, s² d¹ metals">3</span></a></li> <li><a href="/wiki/Group_4_element" title="Group 4 element"><span title="Group 4: Ti, Zr, Hf, Rf — titanium and analogs, transition metals with 4 valence electrons">4</span></a></li> <li><a href="/wiki/Group_5_element" title="Group 5 element"><span title="Group 5: V, Nb, Ta, Db — vanadium and analogs, transition metals with 5 valence electrons">5</span></a></li> <li><a href="/wiki/Group_6_element" title="Group 6 element"><span title="Group 6: Cr, Mo, W, Sg — chromium and analogs, transition metals with 6 valence electrons">6</span></a></li> <li><a href="/wiki/Group_7_element" title="Group 7 element"><span title="Group 7: Mn, Tc, Re, Bh — manganese and analogs, transition metals with 7 valence electrons">7</span></a></li> <li><a href="/wiki/Group_8_element" title="Group 8 element"><span title="Group 8: Fe, Ru, Os, Hs — iron and analogs, transition metals with 8 valence electrons">8</span></a></li> <li><a href="/wiki/Group_9_element" title="Group 9 element"><span title="Group 9: Co, Rh, Ir, Mt — cobalt and analogs, transition metals with 9 valence electrons">9</span></a></li> <li><a href="/wiki/Group_10_element" title="Group 10 element"><span title="Group 10: Ni, Pd, Pt, Ds — nickel and analogs, transition metals with 10 valence electrons">10</span></a></li> <li><a href="/wiki/Group_11_element" title="Group 11 element"><span title="Group 11: Cu, Ag, Au, Rg — coinage metals, transition metals with 11 valence electrons">11</span></a></li> <li><a href="/wiki/Group_12_element" title="Group 12 element"><span title="Group 12: Zn, Cd, Hg, Cn — zinc group, s² d¹⁰ metals">12</span></a></li> <li><a href="/wiki/Boron_group" title="Boron group"><span title="Group 13: B, Al, Ga, In, Tl, Nh — boron group, s² p¹ elements">13</span></a></li> <li><a href="/wiki/Carbon_group" title="Carbon group"><span title="Group 14: C, Si, Ge, Sn, Pb, Fl — carbon group, s² p² elements">14</span></a></li> <li><a href="/wiki/Pnictogen" title="Pnictogen"><span title="Group 15: N, P, As, Sb, Bi, Mc — nitrogen group, s² p³ elements" class="nowrap">15 <i>(pnictogens)</i></span></a></li> <li><a href="/wiki/Chalcogen" title="Chalcogen"><span title="Group 16: O, S, Se, Te, Po, Lv — oxygen group, s² p⁴ elements" class="nowrap">16 <i>(chalcogens)</i></span></a></li> <li><a href="/wiki/Halogen" title="Halogen"><span title="Group 17: F, Cl, Br, I, At, Ts — fluorine group, s² p⁵ elements" class="nowrap">17 <i>(halogens)</i></span></a></li> <li><a href="/wiki/Noble_gas" title="Noble gas"><span title="Group 18: He, Ne, Ar, Kr, Xe, Rn, Og — elements having a complete valence shell" class="nowrap">18 <i>(noble gases)</i></span></a></li></ul> <div style="clear:both;" class=""></div> <ul><li><b><a href="/wiki/Period_(periodic_table)" title="Period (periodic table)">Periods</a> (1–7, ...)</b></li></ul> <div style="clear:both;" class=""></div> <ul><li><a href="/wiki/Period_1_element" title="Period 1 element"><span title="Period 1: H, He, Z = 1–2">1</span></a></li> <li><a href="/wiki/Period_2_element" title="Period 2 element"><span title="Period 2: Li … Ne, Z = 3–10">2</span></a></li> <li><a href="/wiki/Period_3_element" title="Period 3 element"><span title="Period 3: Na … Ar, Z = 11–18">3</span></a></li> <li><a href="/wiki/Period_4_element" title="Period 4 element"><span title="Period 4: K … Kr, Z = 19–36">4</span></a></li> <li><a href="/wiki/Period_5_element" title="Period 5 element"><span title="Period 5: Rb … Xe, Z = 37–54">5</span></a></li> <li><a href="/wiki/Period_6_element" title="Period 6 element"><span title="Period 6: Cs … Rn, Z = 55–86">6</span></a></li> <li><a href="/wiki/Period_7_element" title="Period 7 element"><span title="Period 7: Fr … Og, Z = 87–118">7</span></a></li> <li><a href="/wiki/Extended_periodic_table" title="Extended periodic table"><span title="Periods 8+: Z = 119 …: Afbau, Fricke, and Pyykkö models">8+</span></a></li></ul> <div style="clear:both;" class=""></div> <ul><li><b><a href="/wiki/Block_(periodic_table)" title="Block (periodic table)">Blocks</a> (s, p, d, f, ...)</b></li></ul> <div style="clear:both;" class=""></div> <ul><li><ul><li><a href="/wiki/Atomic_orbital" title="Atomic orbital">Atomic orbitals</a></li> <li><a href="/wiki/Aufbau_principle" title="Aufbau principle">Aufbau principle</a></li></ul></li></ul></div></div></td> </tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="border-top:1px solid #aaa;;color: var(--color-base)">By <a href="/wiki/Properties_of_metals,_metalloids_and_nonmetals" title="Properties of metals, metalloids and nonmetals">metallic classification</a></div><div class="sidebar-list-content mw-collapsible-content"> <ul><li><b><a href="/wiki/Metal" title="Metal">Metals</a></b></li></ul> <div style="clear:both;" class=""></div> <ul><li><a href="/wiki/Alkali_metal" title="Alkali metal">alkali</a></li> <li><a href="/wiki/Alkaline_earth_metal" title="Alkaline earth metal">alkaline earth</a></li></ul> <div style="clear:both;" class=""></div> <ul><li><a href="/wiki/Transition_metal" title="Transition metal">transition</a></li> <li><a href="/wiki/Post-transition_metal" title="Post-transition metal">post-transition</a></li></ul> <div style="clear:both;" class=""></div> <ul><li><a href="/wiki/Lanthanide" title="Lanthanide">lanthanide</a></li> <li><a href="/wiki/Actinide" title="Actinide">actinide</a></li></ul> <div style="clear:both;" class=""></div> <ul><li><b><a href="/wiki/Metalloid" title="Metalloid">Metalloids</a></b></li></ul> <div style="clear:both;" class=""></div> <ul><li><ul><li><a href="/wiki/Dividing_line_between_metals_and_nonmetals" title="Dividing line between metals and nonmetals">dividing metals and nonmetals</a></li></ul></li></ul> <div style="clear:both;" class=""></div> <ul><li><b><a href="/wiki/Nonmetal" title="Nonmetal">Nonmetals</a></b></li></ul> <div style="clear:both;" class=""></div> <ul><li><a href="/wiki/Halogen" title="Halogen">nonmetal halogen</a></li> <li><a href="/wiki/Noble_gas" title="Noble gas">noble gas</a></li></ul></div></div></td> </tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="border-top:1px solid #aaa;;color: var(--color-base)">By other characteristics</div><div class="sidebar-list-content mw-collapsible-content"> <ul><li><a href="/wiki/Coinage_metals" title="Coinage metals">Coinage metals</a></li> <li><a href="/wiki/Platinum_group" title="Platinum group">Platinum-group metals</a></li></ul> <div style="clear:both;" class=""></div> <ul><li><a href="/wiki/Precious_metal" title="Precious metal">Precious metals</a></li> <li><a href="/wiki/Refractory_metals" title="Refractory metals">Refractory metals</a></li></ul> <div style="clear:both;" class=""></div> <ul><li><a href="/wiki/Heavy_metal_element" title="Heavy metal element">Heavy metals</a></li> <li><a href="/wiki/Light_metal" title="Light metal">Light metals</a></li></ul> <div style="clear:both;" class=""></div> <ul><li><a href="/wiki/Native_metal" title="Native metal">Native metals</a></li> <li><a href="/wiki/Noble_metal" title="Noble metal">Noble metals</a></li></ul> <div style="clear:both;" class=""></div> <ul><li><a href="/wiki/Main-group_element" title="Main-group element">Main-group elements</a></li> <li><a href="/wiki/Rare-earth_element" title="Rare-earth element">Rare-earth elements</a></li></ul> <div style="clear:both;" class=""></div> <ul><li><a href="/wiki/Transuranium_element" title="Transuranium element">Transuranium</a> elements</li></ul> <div style="clear:both;" class=""></div> <ul><li><a href="/wiki/Major_actinide" title="Major actinide">Major</a>, <a href="/wiki/Minor_actinide" title="Minor actinide">minor</a> and <a href="/wiki/Superheavy_element" title="Superheavy element">trans-</a> actinides</li></ul></div></div></td> </tr><tr><td class="sidebar-content" style="border-top:1px solid #aaa; text-align:left; background:#eeeeff;"> <div class="center" style="width:auto; margin-left:auto; margin-right:auto;"><b><a href="/wiki/Chemical_element" title="Chemical element">Elements</a></b></div></td> </tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="border-top:1px solid #aaa;;color: var(--color-base)"><a href="/wiki/List_of_chemical_elements" title="List of chemical elements">List of chemical elements</a></div><div class="sidebar-list-content mw-collapsible-content"> <ul><li><a href="/wiki/Abundance_of_the_chemical_elements" title="Abundance of the chemical elements">by abundance</a> (<a href="/wiki/Composition_of_the_human_body" title="Composition of the human body">in human body</a>)</li></ul> <div style="clear:both;" class=""></div> <ul><li><a href="/wiki/List_of_elements_by_atomic_properties" title="List of elements by atomic properties">by atomic properties</a></li> <li><a href="/wiki/List_of_elements_by_stability_of_isotopes" title="List of elements by stability of isotopes">by isotope stability</a></li></ul> <div style="clear:both;" class=""></div> <ul><li><a href="/wiki/Chemical_symbol" title="Chemical symbol">by symbol</a></li></ul></div></div></td> </tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="border-top:1px solid #aaa;;color: var(--color-base)"><a href="/wiki/Chemical_element#Properties" title="Chemical element">Properties of elements</a></div><div class="sidebar-list-content mw-collapsible-content"> <ul><li><a href="/wiki/Relative_atomic_mass" title="Relative atomic mass">Relative atomic mass</a></li> <li><a href="/wiki/Periodic_table_(crystal_structure)" title="Periodic table (crystal structure)">Crystal structure</a></li></ul> <div style="clear:both;" class=""></div> <ul><li>Electron <a href="/wiki/Electron_affinity" title="Electron affinity">affinity</a></li> <li><a href="/wiki/Electron_configuration" title="Electron configuration">configuration</a></li></ul> <div style="clear:both;" class=""></div> <ul><li><a href="/wiki/Electronegativity" title="Electronegativity">Electronegativity</a> (<a href="/wiki/Electronegativity#Allen_electronegativity" title="Electronegativity">Allen</a>, <a href="/wiki/Electronegativity#Pauling_electronegativity" title="Electronegativity">Pauling</a>)</li></ul> <div style="clear:both;" class=""></div> <ul><li><a href="/wiki/Goldschmidt_classification" title="Goldschmidt classification">Goldschmidt classification</a></li></ul> <div style="clear:both;" class=""></div> <ul><li><a href="/wiki/Mineral_(nutrient)" title="Mineral (nutrient)">Nutrition</a></li> <li><a href="/wiki/Valence_(chemistry)" title="Valence (chemistry)">Valence</a></li></ul></div></div></td> </tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="border-top:1px solid #aaa;;color: var(--color-base)">Data pages for elements</div><div class="sidebar-list-content mw-collapsible-content"> <ul><li><a href="/wiki/Abundances_of_the_elements_(data_page)" title="Abundances of the elements (data page)">Abundance</a></li> <li><a href="/wiki/Atomic_radii_of_the_elements_(data_page)" title="Atomic radii of the elements (data page)">Atomic radius</a></li> <li><a href="/wiki/Boiling_points_of_the_elements_(data_page)" title="Boiling points of the elements (data page)">Boiling point</a></li> <li><a href="/wiki/Critical_points_of_the_elements_(data_page)" title="Critical points of the elements (data page)">Critical point</a></li> <li><a href="/wiki/Densities_of_the_elements_(data_page)" title="Densities of the elements (data page)">Density</a></li> <li><a href="/wiki/Elastic_properties_of_the_elements_(data_page)" title="Elastic properties of the elements (data page)">Elasticity</a></li> <li><a href="/wiki/Electrical_resistivities_of_the_elements_(data_page)" title="Electrical resistivities of the elements (data page)">Electrical resistivity</a></li> <li>Electron <a href="/wiki/Electron_affinity_(data_page)" title="Electron affinity (data page)">affinity</a> / <a href="/wiki/Electron_configurations_of_the_elements_(data_page)" title="Electron configurations of the elements (data page)">configuration</a></li> <li><a href="/wiki/Electronegativities_of_the_elements_(data_page)" title="Electronegativities of the elements (data page)">Electronegativity</a></li> <li><a href="/wiki/Hardnesses_of_the_elements_(data_page)" title="Hardnesses of the elements (data page)">Hardness</a></li> <li>Heat <a href="/wiki/Heat_capacities_of_the_elements_(data_page)" title="Heat capacities of the elements (data page)">capacity</a> / <a href="/wiki/Heats_of_fusion_of_the_elements_(data_page)" title="Heats of fusion of the elements (data page)">of fusion</a> / <a href="/wiki/Heats_of_vaporization_of_the_elements_(data_page)" title="Heats of vaporization of the elements (data page)">of vaporization</a></li> <li><a href="/wiki/Ionization_energies_of_the_elements_(data_page)" title="Ionization energies of the elements (data page)">Ionization energy</a></li> <li><a href="/wiki/Melting_points_of_the_elements_(data_page)" title="Melting points of the elements (data page)">Melting point</a></li> <li><a href="/wiki/Oxidation_state" title="Oxidation state">Oxidation state</a></li> <li><a href="/wiki/Speeds_of_sound_of_the_elements" title="Speeds of sound of the elements">Speed of sound</a></li> <li>Thermal <a href="/wiki/Thermal_conductivities_of_the_elements_(data_page)" title="Thermal conductivities of the elements (data page)">conductivity</a> / <a href="/wiki/Thermal_expansivities_of_the_elements" title="Thermal expansivities of the elements">expansion coefficient</a></li> <li><a href="/wiki/Vapor_pressures_of_the_elements_(data_page)" title="Vapor pressures of the elements (data page)">Vapor pressure</a></li></ul></div></div></td> </tr><tr><td class="sidebar-content" style="border-top:1px solid #aaa; border-bottom:1px solid #aaa; background:#eeeeff;"> <ul><li><b><a href="/wiki/Category:Periodic_table" title="Category:Periodic table">Category</a></b></li> <li><b><a href="/wiki/Portal:Chemistry" title="Portal:Chemistry">Chemistry Portal</a></b></li></ul></td> </tr><tr><td class="sidebar-navbar"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1239400231">.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini abbr{font-variant:small-caps;border-bottom:none;text-decoration:none;cursor:inherit}.mw-parser-output .navbar-ct-full{font-size:114%;margin:0 7em}.mw-parser-output .navbar-ct-mini{font-size:114%;margin:0 4em}html.skin-theme-clientpref-night .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Sidebar_periodic_table" title="Template:Sidebar periodic table"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Sidebar_periodic_table" title="Template talk:Sidebar periodic table"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Sidebar_periodic_table" title="Special:EditPage/Template:Sidebar periodic table"><abbr title="Edit this template">e</abbr></a></li></ul></div></td></tr></tbody></table> <p>The <b>periodic table</b>, also known as the <b>periodic table of the elements</b>, is an ordered arrangement of the <a href="/wiki/Chemical_element" title="Chemical element">chemical elements</a> into rows ("<a href="/wiki/Period_(periodic_table)" title="Period (periodic table)">periods</a>") and columns ("<a href="/wiki/Group_(periodic_table)" title="Group (periodic table)">groups</a>"). It is an <a href="/wiki/Cultural_icon" title="Cultural icon">icon</a> of <a href="/wiki/Chemistry" title="Chemistry">chemistry</a> and is widely used in <a href="/wiki/Physics" title="Physics">physics</a> and other sciences. It is a depiction of the <a href="/wiki/Periodic_trends" title="Periodic trends">periodic law</a>, which states that when the elements are arranged in order of their <a href="/wiki/Atomic_number" title="Atomic number">atomic numbers</a> an approximate <a href="/wiki/Periodic_function" title="Periodic function">recurrence of their properties</a> is evident. The table is divided into four roughly rectangular areas called <a href="/wiki/Block_(periodic_table)" title="Block (periodic table)">blocks</a>. Elements in the same group tend to show similar chemical characteristics. </p><p>Vertical, horizontal and diagonal <a href="/wiki/Periodic_trends" title="Periodic trends">trends</a> characterize the periodic table. <a href="/wiki/Metal" title="Metal">Metallic</a> character increases going down a group and from right to left across a period. <a href="/wiki/Nonmetal_(chemistry)" class="mw-redirect" title="Nonmetal (chemistry)">Nonmetallic</a> character increases going from the bottom left of the periodic table to the top right. </p><p>The first periodic table to become generally accepted was that of the Russian chemist <a href="/wiki/Dmitri_Mendeleev" title="Dmitri Mendeleev">Dmitri Mendeleev</a> in 1869; he formulated the periodic law as a dependence of chemical properties on <a href="/wiki/Atomic_mass" title="Atomic mass">atomic mass</a>. As not all elements were then known, there were gaps in his periodic table, and Mendeleev successfully used the periodic law to <a href="/wiki/Mendeleev%27s_predicted_elements" title="Mendeleev's predicted elements">predict some properties of some of the missing elements</a>. The periodic law was recognized as a fundamental discovery in the late 19th century. It was explained early in the 20th century, with the discovery of <a href="/wiki/Atomic_number" title="Atomic number">atomic numbers</a> and associated pioneering work in <a href="/wiki/Quantum_mechanics" title="Quantum mechanics">quantum mechanics</a>, both ideas serving to illuminate the internal structure of the atom. A recognisably modern form of the table was reached in 1945 with <a href="/wiki/Glenn_T._Seaborg" title="Glenn T. Seaborg">Glenn T. Seaborg</a>'s discovery that the <a href="/wiki/Actinide" title="Actinide">actinides</a> were in fact f-block rather than d-block elements. The periodic table and law are now a central and indispensable part of modern chemistry. </p><p>The periodic table continues to evolve with the progress of science. In nature, only elements up to atomic number 94 exist;<sup id="cite_ref-transuranium_1-0" class="reference"><a href="#cite_note-transuranium-1"><span class="cite-bracket">[</span>a<span class="cite-bracket">]</span></a></sup> to go further, it was necessary to <a href="/wiki/Synthetic_element" title="Synthetic element">synthesize</a> new elements in the laboratory. By 2010, the first 118 elements were known, thereby completing the first seven rows of the table;<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> however, chemical characterization is still needed for the heaviest elements to confirm that their properties match their positions. New discoveries will extend the table <a href="/wiki/Extended_periodic_table" title="Extended periodic table">beyond these seven rows</a>, though it is not yet known how many more elements are possible; moreover, theoretical calculations suggest that this unknown region will not follow the patterns of the known part of the table. Some scientific discussion also continues regarding whether some elements are correctly positioned in today's table. Many <a href="/wiki/Alternative_periodic_tables" class="mw-redirect" title="Alternative periodic tables">alternative representations</a> of the periodic law exist, and there is some discussion as to whether there is an optimal form of the periodic table. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Structure">Structure<span class="anchor" id="Detailed_table"></span></h2></div> <div style="background:#f8f8f8; font-size:90%; border:1px solid #a9a9a9; width:100%; max-width:1800px; margin:0 auto; padding:2px; text-align:center; vertical-align:top; box-sizing: border-box; clear: both"> <div style="background:#d8d8d8; padding:2px 1em;font-weight:bold;"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-collapse navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Periodic_table" title="Template:Periodic table"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Periodic_table" title="Template talk:Periodic table"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Periodic_table" title="Special:EditPage/Template:Periodic table"><abbr title="Edit this template">e</abbr></a></li></ul></div><div class="navbar-ct-mini"><a class="mw-selflink selflink">Periodic table</a></div></div><div class="mw-collapsible-content"> <table style="border-spacing:1px;display:block;overflow:auto;width:100%;margin:0 !important"> <tbody><tr style="line-height:125%; vertical-align:top;"> <th style="text-align:left; width:5%"><a href="/wiki/Group_(periodic_table)" title="Group (periodic table)">Group</a> </th> <th style="background:#e8e8e8; width:5%"><a href="/wiki/Alkali_metal" title="Alkali metal">1</a> </th> <th style="background:#f0f0f0; width:5%"><a href="/wiki/Alkaline_earth_metal" title="Alkaline earth metal">2</a> </th> <th style="width:2%">  </th> <th style="background:#e8e8e8; width:5%"><a href="/wiki/Group_3_element" title="Group 3 element">3</a> </th> <th style="background:#f0f0f0; width:5%"><a href="/wiki/Group_4_element" title="Group 4 element">4</a> </th> <th style="background:#e8e8e8; width:5%"><a href="/wiki/Group_5_element" title="Group 5 element">5</a> </th> <th style="background:#f0f0f0; width:5%"><a href="/wiki/Group_6_element" title="Group 6 element">6</a> </th> <th style="background:#e8e8e8; width:5%"><a href="/wiki/Group_7_element" title="Group 7 element">7</a> </th> <th style="background:#f0f0f0; width:5%"><a href="/wiki/Group_8_element" title="Group 8 element">8</a> </th> <th style="background:#e8e8e8; width:5%"><a href="/wiki/Group_9_element" title="Group 9 element">9</a> </th> <th style="background:#f0f0f0; width:5%"><a href="/wiki/Group_10_element" title="Group 10 element">10</a> </th> <th style="background:#e8e8e8; width:5%"><a href="/wiki/Group_11_element" title="Group 11 element">11</a> </th> <th style="background:#f0f0f0; width:5%"><a href="/wiki/Group_12_element" title="Group 12 element">12</a> </th> <th style="background:#e8e8e8; width:5%"><a href="/wiki/Boron_group" title="Boron group">13</a> </th> <th style="background:#f0f0f0; width:5%"><a href="/wiki/Carbon_group" title="Carbon group">14</a> </th> <th style="background:#e8e8e8; width:5%"><a href="/wiki/Pnictogen" title="Pnictogen">15</a> </th> <th style="background:#f0f0f0; width:5%"><a href="/wiki/Chalcogen" title="Chalcogen">16</a> </th> <th style="background:#e8e8e8; width:5%"><a href="/wiki/Halogen" title="Halogen">17</a> </th> <th style="background:#f0f0f0; width:5%"><a href="/wiki/Noble_gas" title="Noble gas">18</a> </th></tr> <tr style="line-height:125%; vertical-align:top;"> <td> </td> <td style="background:#e8e8e8;">Hydrogen &<br />alkali metals </td> <td style="background:#f0f0f0;">Alkaline earth metals </td> <td> </td> <td style="background:#e8e8e8;"> </td> <td style="background:#f0f0f0;"> </td> <td style="background:#e8e8e8;"> </td> <td style="background:#f0f0f0;"> </td> <td style="background:#e8e8e8;"> </td> <td style="background:#f0f0f0;"> </td> <td style="background:#e8e8e8;"> </td> <td style="background:#f0f0f0;"> </td> <td style="background:#e8e8e8;"> </td> <td style="background:#f0f0f0;"> </td> <td style="background:#e8e8e8;">Triels </td> <td style="background:#f0f0f0;">Tetrels </td> <td style="background:#e8e8e8;">Pnicto­gens </td> <td style="background:#f0f0f0;">Chal­co­gens </td> <td style="background:#e8e8e8;">Halo­gens </td> <td style="background:#f0f0f0;">Noble<br />gases </td></tr> <tr> <th><a href="/wiki/Period_(periodic_table)" title="Period (periodic table)">Period</a><br /> <p><a href="/wiki/Period_1_element" title="Period 1 element">1</a> </p> </th> <td><span class="nounderlines"><a href="/wiki/Hydrogen" title="Hydrogen"><span title="H , hydrogen" style="background-color: #ff9999; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Hydro­gen</span><span style="color: #000000; display:block;">1</span><span style="display:block; font-size:112%; font-weight:bold;">H</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7000100800000000000♠"></span>1.0080</span></span></span></a></span> </td> <td colspan="17"> </td> <td><span class="nounderlines"><a href="/wiki/Helium" title="Helium"><span title="He, helium" style="background-color: #ff9999; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">He­lium</span><span style="color: #000000; display:block;">2</span><span style="display:block; font-size:112%; font-weight:bold;">He</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7000400260000000000♠"></span>4.0026</span></span></span></a></span> </td></tr> <tr> <th><a href="/wiki/Period_2_element" title="Period 2 element">2</a> </th> <td><span class="nounderlines"><a href="/wiki/Lithium" title="Lithium"><span title="Li, lithium" style="background-color: #ff9999; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Lith­ium</span><span style="color: #000000; display:block;">3</span><span style="display:block; font-size:112%; font-weight:bold;">Li</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7000694000000000000♠"></span>6.94</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Beryllium" title="Beryllium"><span title="Be, beryllium" style="background-color: #ff9999; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Beryl­lium</span><span style="color: #000000; display:block;">4</span><span style="display:block; font-size:112%; font-weight:bold;">Be</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7000901220000000000♠"></span>9.0122</span></span></span></a></span> </td> <td colspan="11"> </td> <td><span class="nounderlines"><a href="/wiki/Boron" title="Boron"><span title="B , boron" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Boron</span><span style="color: #000000; display:block;">5</span><span style="display:block; font-size:112%; font-weight:bold;">B</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001108100000000000♠"></span>10.81</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Carbon" title="Carbon"><span title="C , carbon" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Carbon</span><span style="color: #000000; display:block;">6</span><span style="display:block; font-size:112%; font-weight:bold;">C</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001120110000000000♠"></span>12.011</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Nitrogen" title="Nitrogen"><span title="N , nitrogen" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Nitro­gen</span><span style="color: #000000; display:block;">7</span><span style="display:block; font-size:112%; font-weight:bold;">N</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001140070000000000♠"></span>14.007</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Oxygen" title="Oxygen"><span title="O , oxygen" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Oxy­gen</span><span style="color: #000000; display:block;">8</span><span style="display:block; font-size:112%; font-weight:bold;">O</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001159990000000000♠"></span>15.999</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Fluorine" title="Fluorine"><span title="F , fluorine" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Fluor­ine</span><span style="color: #000000; display:block;">9</span><span style="display:block; font-size:112%; font-weight:bold;">F</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001189980000000000♠"></span>18.998</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Neon" title="Neon"><span title="Ne, neon" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Neon</span><span style="color: #000000; display:block;">10</span><span style="display:block; font-size:112%; font-weight:bold;">Ne</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001201800000000000♠"></span>20.180</span></span></span></a></span> </td></tr> <tr> <th><a href="/wiki/Period_3_element" title="Period 3 element">3</a> </th> <td><span class="nounderlines"><a href="/wiki/Sodium" title="Sodium"><span title="Na, sodium" style="background-color: #ff9999; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">So­dium</span><span style="color: #000000; display:block;">11</span><span style="display:block; font-size:112%; font-weight:bold;">Na</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001229899999999999♠"></span>22.990</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Magnesium" title="Magnesium"><span title="Mg, magnesium" style="background-color: #ff9999; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Magne­sium</span><span style="color: #000000; display:block;">12</span><span style="display:block; font-size:112%; font-weight:bold;">Mg</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001243050000000000♠"></span>24.305</span></span></span></a></span> </td> <td colspan="11"> </td> <td><span class="nounderlines"><a href="/wiki/Aluminium" title="Aluminium"><span title="Al, aluminium" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Alumin­ium</span><span style="color: #000000; display:block;">13</span><span style="display:block; font-size:112%; font-weight:bold;">Al</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001269820000000000♠"></span>26.982</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Silicon" title="Silicon"><span title="Si, silicon" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Sili­con</span><span style="color: #000000; display:block;">14</span><span style="display:block; font-size:112%; font-weight:bold;">Si</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001280850000000000♠"></span>28.085</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Phosphorus" title="Phosphorus"><span title="P , phosphorus" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Phos­phorus</span><span style="color: #000000; display:block;">15</span><span style="display:block; font-size:112%; font-weight:bold;">P</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001309740000000000♠"></span>30.974</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Sulfur" title="Sulfur"><span title="S , sulfur" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Sulfur</span><span style="color: #000000; display:block;">16</span><span style="display:block; font-size:112%; font-weight:bold;">S</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001320600000000000♠"></span>32.06</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Chlorine" title="Chlorine"><span title="Cl, chlorine" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Chlor­ine</span><span style="color: #000000; display:block;">17</span><span style="display:block; font-size:112%; font-weight:bold;">Cl</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001354500000000000♠"></span>35.45</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Argon" title="Argon"><span title="Ar, argon" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Argon</span><span style="color: #000000; display:block;">18</span><span style="display:block; font-size:112%; font-weight:bold;">Ar</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001399500000000000♠"></span>39.95</span></span></span></a></span> </td></tr> <tr> <th><a href="/wiki/Period_4_element" title="Period 4 element">4</a> </th> <td><span class="nounderlines"><a href="/wiki/Potassium" title="Potassium"><span title="K , potassium" style="background-color: #ff9999; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Potas­sium</span><span style="color: #000000; display:block;">19</span><span style="display:block; font-size:112%; font-weight:bold;">K</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001390980000000000♠"></span>39.098</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Calcium" title="Calcium"><span title="Ca, calcium" style="background-color: #ff9999; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Cal­cium</span><span style="color: #000000; display:block;">20</span><span style="display:block; font-size:112%; font-weight:bold;">Ca</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001400780000000000♠"></span>40.078</span></span></span></a></span> </td> <td> </td> <td><span class="nounderlines"><a href="/wiki/Scandium" title="Scandium"><span title="Sc, scandium" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Scan­dium</span><span style="color: #000000; display:block;">21</span><span style="display:block; font-size:112%; font-weight:bold;">Sc</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001449560000000000♠"></span>44.956</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Titanium" title="Titanium"><span title="Ti, titanium" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Tita­nium</span><span style="color: #000000; display:block;">22</span><span style="display:block; font-size:112%; font-weight:bold;">Ti</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001478670000000000♠"></span>47.867</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Vanadium" title="Vanadium"><span title="V , vanadium" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Vana­dium</span><span style="color: #000000; display:block;">23</span><span style="display:block; font-size:112%; font-weight:bold;">V</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001509420000000000♠"></span>50.942</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Chromium" title="Chromium"><span title="Cr, chromium" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Chrom­ium</span><span style="color: #000000; display:block;">24</span><span style="display:block; font-size:112%; font-weight:bold;">Cr</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001519960000000000♠"></span>51.996</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Manganese" title="Manganese"><span title="Mn, manganese" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Manga­nese</span><span style="color: #000000; display:block;">25</span><span style="display:block; font-size:112%; font-weight:bold;">Mn</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001549380000000000♠"></span>54.938</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Iron" title="Iron"><span title="Fe, iron" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Iron</span><span style="color: #000000; display:block;">26</span><span style="display:block; font-size:112%; font-weight:bold;">Fe</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001558450000000000♠"></span>55.845</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Cobalt" title="Cobalt"><span title="Co, cobalt" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Cobalt</span><span style="color: #000000; display:block;">27</span><span style="display:block; font-size:112%; font-weight:bold;">Co</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001589330000000000♠"></span>58.933</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Nickel" title="Nickel"><span title="Ni, nickel" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Nickel</span><span style="color: #000000; display:block;">28</span><span style="display:block; font-size:112%; font-weight:bold;">Ni</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001586930000000000♠"></span>58.693</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Copper" title="Copper"><span title="Cu, copper" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Copper</span><span style="color: #000000; display:block;">29</span><span style="display:block; font-size:112%; font-weight:bold;">Cu</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001635460000000000♠"></span>63.546</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Zinc" title="Zinc"><span title="Zn, zinc" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Zinc</span><span style="color: #000000; display:block;">30</span><span style="display:block; font-size:112%; font-weight:bold;">Zn</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001653800000000000♠"></span>65.38</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Gallium" title="Gallium"><span title="Ga, gallium" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Gallium</span><span style="color: #000000; display:block;">31</span><span style="display:block; font-size:112%; font-weight:bold;">Ga</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001697230000000000♠"></span>69.723</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Germanium" title="Germanium"><span title="Ge, germanium" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Germa­nium</span><span style="color: #000000; display:block;">32</span><span style="display:block; font-size:112%; font-weight:bold;">Ge</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001726300000000000♠"></span>72.630</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Arsenic" title="Arsenic"><span title="As, arsenic" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Arsenic</span><span style="color: #000000; display:block;">33</span><span style="display:block; font-size:112%; font-weight:bold;">As</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001749220000000000♠"></span>74.922</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Selenium" title="Selenium"><span title="Se, selenium" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Sele­nium</span><span style="color: #000000; display:block;">34</span><span style="display:block; font-size:112%; font-weight:bold;">Se</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001789710000000000♠"></span>78.971</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Bromine" title="Bromine"><span title="Br, bromine" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Bromine</span><span style="color: #000000; display:block;">35</span><span style="display:block; font-size:112%; font-weight:bold;">Br</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001799040000000000♠"></span>79.904</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Krypton" title="Krypton"><span title="Kr, krypton" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Kryp­ton</span><span style="color: #000000; display:block;">36</span><span style="display:block; font-size:112%; font-weight:bold;">Kr</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001837980000000000♠"></span>83.798</span></span></span></a></span> </td></tr> <tr> <th><a href="/wiki/Period_5_element" title="Period 5 element">5</a> </th> <td><span class="nounderlines"><a href="/wiki/Rubidium" title="Rubidium"><span title="Rb, rubidium" style="background-color: #ff9999; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Rubid­ium</span><span style="color: #000000; display:block;">37</span><span style="display:block; font-size:112%; font-weight:bold;">Rb</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001854680000000000♠"></span>85.468</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Strontium" title="Strontium"><span title="Sr, strontium" style="background-color: #ff9999; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Stront­ium</span><span style="color: #000000; display:block;">38</span><span style="display:block; font-size:112%; font-weight:bold;">Sr</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001876200000000000♠"></span>87.62</span></span></span></a></span> </td> <td> </td> <td><span class="nounderlines"><a href="/wiki/Yttrium" title="Yttrium"><span title="Y , yttrium" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Yttrium</span><span style="color: #000000; display:block;">39</span><span style="display:block; font-size:112%; font-weight:bold;">Y</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001889060000000000♠"></span>88.906</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Zirconium" title="Zirconium"><span title="Zr, zirconium" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Zirco­nium</span><span style="color: #000000; display:block;">40</span><span style="display:block; font-size:112%; font-weight:bold;">Zr</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001912240000000000♠"></span>91.224</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Niobium" title="Niobium"><span title="Nb, niobium" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Nio­bium</span><span style="color: #000000; display:block;">41</span><span style="display:block; font-size:112%; font-weight:bold;">Nb</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001929060000000000♠"></span>92.906</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Molybdenum" title="Molybdenum"><span title="Mo, molybdenum" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Molyb­denum</span><span style="color: #000000; display:block;">42</span><span style="display:block; font-size:112%; font-weight:bold;">Mo</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7001959500000000000♠"></span>95.95</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Technetium" title="Technetium"><span title="Tc, technetium" style="background-color: #99ccff; border-top: 2px dashed #6e6e8e; border-bottom: 2px dashed #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Tech­netium</span><span style="color: #000000; display:block;">43</span><span style="display:block; font-size:112%; font-weight:bold;">Tc</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[97]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Ruthenium" title="Ruthenium"><span title="Ru, ruthenium" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Ruthe­nium</span><span style="color: #000000; display:block;">44</span><span style="display:block; font-size:112%; font-weight:bold;">Ru</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002101070000000000♠"></span>101.07</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Rhodium" title="Rhodium"><span title="Rh, rhodium" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Rho­dium</span><span style="color: #000000; display:block;">45</span><span style="display:block; font-size:112%; font-weight:bold;">Rh</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002102910000000000♠"></span>102.91</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Palladium" title="Palladium"><span title="Pd, palladium" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Pallad­ium</span><span style="color: #000000; display:block;">46</span><span style="display:block; font-size:112%; font-weight:bold;">Pd</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002106420000000000♠"></span>106.42</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Silver" title="Silver"><span title="Ag, silver" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Silver</span><span style="color: #000000; display:block;">47</span><span style="display:block; font-size:112%; font-weight:bold;">Ag</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002107870000000000♠"></span>107.87</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Cadmium" title="Cadmium"><span title="Cd, cadmium" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Cad­mium</span><span style="color: #000000; display:block;">48</span><span style="display:block; font-size:112%; font-weight:bold;">Cd</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002112410000000000♠"></span>112.41</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Indium" title="Indium"><span title="In, indium" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Indium</span><span style="color: #000000; display:block;">49</span><span style="display:block; font-size:112%; font-weight:bold;">In</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002114820000000000♠"></span>114.82</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Tin" title="Tin"><span title="Sn, tin" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Tin</span><span style="color: #000000; display:block;">50</span><span style="display:block; font-size:112%; font-weight:bold;">Sn</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002118710000000000♠"></span>118.71</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Antimony" title="Antimony"><span title="Sb, antimony" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Anti­mony</span><span style="color: #000000; display:block;">51</span><span style="display:block; font-size:112%; font-weight:bold;">Sb</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002121760000000000♠"></span>121.76</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Tellurium" title="Tellurium"><span title="Te, tellurium" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Tellur­ium</span><span style="color: #000000; display:block;">52</span><span style="display:block; font-size:112%; font-weight:bold;">Te</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002127600000000000♠"></span>127.60</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Iodine" title="Iodine"><span title="I , iodine" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Iodine</span><span style="color: #000000; display:block;">53</span><span style="display:block; font-size:112%; font-weight:bold;">I</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002126900000000000♠"></span>126.90</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Xenon" title="Xenon"><span title="Xe, xenon" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Xenon</span><span style="color: #000000; display:block;">54</span><span style="display:block; font-size:112%; font-weight:bold;">Xe</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002131289999999999♠"></span>131.29</span></span></span></a></span> </td></tr> <tr> <th><a href="/wiki/Period_6_element" title="Period 6 element">6</a> </th> <td><span class="nounderlines"><a href="/wiki/Caesium" title="Caesium"><span title="Cs, caesium" style="background-color: #ff9999; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Cae­sium</span><span style="color: #000000; display:block;">55</span><span style="display:block; font-size:112%; font-weight:bold;">Cs</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002132910000000000♠"></span>132.91</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Barium" title="Barium"><span title="Ba, barium" style="background-color: #ff9999; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Ba­rium</span><span style="color: #000000; display:block;">56</span><span style="display:block; font-size:112%; font-weight:bold;">Ba</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002137330000000000♠"></span>137.33</span></span></span></a></span> </td> <td style="text-align:center; vertical-align:middle; background:#9bff99"><span class="skin-invert-image" typeof="mw:File"><span><img alt="1 asterisk" src="//upload.wikimedia.org/wikipedia/commons/thumb/4/49/Asterisks_one.svg/16px-Asterisks_one.svg.png" decoding="async" width="16" height="15" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/49/Asterisks_one.svg/24px-Asterisks_one.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/49/Asterisks_one.svg/32px-Asterisks_one.svg.png 2x" data-file-width="106" data-file-height="98" /></span></span> </td> <td><span class="nounderlines"><a href="/wiki/Lutetium" title="Lutetium"><span title="Lu, lutetium" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Lute­tium</span><span style="color: #000000; display:block;">71</span><span style="display:block; font-size:112%; font-weight:bold;">Lu</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002174970000000000♠"></span>174.97</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Hafnium" title="Hafnium"><span title="Hf, hafnium" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Haf­nium</span><span style="color: #000000; display:block;">72</span><span style="display:block; font-size:112%; font-weight:bold;">Hf</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002178490000000000♠"></span>178.49</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Tantalum" title="Tantalum"><span title="Ta, tantalum" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Tanta­lum</span><span style="color: #000000; display:block;">73</span><span style="display:block; font-size:112%; font-weight:bold;">Ta</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002180950000000000♠"></span>180.95</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Tungsten" title="Tungsten"><span title="W , tungsten" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Tung­sten</span><span style="color: #000000; display:block;">74</span><span style="display:block; font-size:112%; font-weight:bold;">W</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002183840000000000♠"></span>183.84</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Rhenium" title="Rhenium"><span title="Re, rhenium" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Rhe­nium</span><span style="color: #000000; display:block;">75</span><span style="display:block; font-size:112%; font-weight:bold;">Re</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002186210000000000♠"></span>186.21</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Osmium" title="Osmium"><span title="Os, osmium" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Os­mium</span><span style="color: #000000; display:block;">76</span><span style="display:block; font-size:112%; font-weight:bold;">Os</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002190230000000000♠"></span>190.23</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Iridium" title="Iridium"><span title="Ir, iridium" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Iridium</span><span style="color: #000000; display:block;">77</span><span style="display:block; font-size:112%; font-weight:bold;">Ir</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002192220000000000♠"></span>192.22</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Platinum" title="Platinum"><span title="Pt, platinum" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Plat­inum</span><span style="color: #000000; display:block;">78</span><span style="display:block; font-size:112%; font-weight:bold;">Pt</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002195080000000000♠"></span>195.08</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Gold" title="Gold"><span title="Au, gold" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Gold</span><span style="color: #000000; display:block;">79</span><span style="display:block; font-size:112%; font-weight:bold;">Au</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002196970000000000♠"></span>196.97</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Mercury_(element)" title="Mercury (element)"><span title="Hg, mercury" style="background-color: #99ccff; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Mer­cury</span><span style="color: #000000; display:block;">80</span><span style="display:block; font-size:112%; font-weight:bold;">Hg</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002200590000000000♠"></span>200.59</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Thallium" title="Thallium"><span title="Tl, thallium" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Thallium</span><span style="color: #000000; display:block;">81</span><span style="display:block; font-size:112%; font-weight:bold;">Tl</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002204380000000000♠"></span>204.38</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Lead" title="Lead"><span title="Pb, lead" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Lead</span><span style="color: #000000; display:block;">82</span><span style="display:block; font-size:112%; font-weight:bold;">Pb</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002207200000000000♠"></span>207.2</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Bismuth" title="Bismuth"><span title="Bi, bismuth" style="background-color: #fdff8c; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Bis­muth</span><span style="color: #000000; display:block;">83</span><span style="display:block; font-size:112%; font-weight:bold;">Bi</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002208980000000000♠"></span>208.98</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Polonium" title="Polonium"><span title="Po, polonium" style="background-color: #fdff8c; border-top: 2px dashed #6e6e8e; border-bottom: 2px dashed #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Polo­nium</span><span style="color: #000000; display:block;">84</span><span style="display:block; font-size:112%; font-weight:bold;">Po</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[209]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Astatine" title="Astatine"><span title="At, astatine" style="background-color: #fdff8c; border-top: 2px dashed #6e6e8e; border-bottom: 2px dashed #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Asta­tine</span><span style="color: #000000; display:block;">85</span><span style="display:block; font-size:112%; font-weight:bold;">At</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[210]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Radon" title="Radon"><span title="Rn, radon" style="background-color: #fdff8c; border-top: 2px dashed #6e6e8e; border-bottom: 2px dashed #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Radon</span><span style="color: #000000; display:block;">86</span><span style="display:block; font-size:112%; font-weight:bold;">Rn</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[222]</span></span></a></span> </td></tr> <tr> <th><a href="/wiki/Period_7_element" title="Period 7 element">7</a> </th> <td><span class="nounderlines"><a href="/wiki/Francium" title="Francium"><span title="Fr, francium" style="background-color: #ff9999; border-top: 2px dashed #6e6e8e; border-bottom: 2px dashed #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Fran­cium</span><span style="color: #000000; display:block;">87</span><span style="display:block; font-size:112%; font-weight:bold;">Fr</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[223]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Radium" title="Radium"><span title="Ra, radium" style="background-color: #ff9999; border-top: 2px dashed #6e6e8e; border-bottom: 2px dashed #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Ra­dium</span><span style="color: #000000; display:block;">88</span><span style="display:block; font-size:112%; font-weight:bold;">Ra</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[226]</span></span></a></span> </td> <td style="text-align:center; vertical-align:middle; background:#9bff99"><span class="skin-invert-image" typeof="mw:File"><span><img alt="1 asterisk" src="//upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Asterisks_2_%28vertical%29.svg/16px-Asterisks_2_%28vertical%29.svg.png" decoding="async" width="16" height="15" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Asterisks_2_%28vertical%29.svg/24px-Asterisks_2_%28vertical%29.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Asterisks_2_%28vertical%29.svg/32px-Asterisks_2_%28vertical%29.svg.png 2x" data-file-width="106" data-file-height="98" /></span></span> </td> <td><span class="nounderlines"><a href="/wiki/Lawrencium" title="Lawrencium"><span title="Lr, lawrencium" style="background-color: #99ccff; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Lawren­cium</span><span style="color: #000000; display:block;">103</span><span style="display:block; font-size:112%; font-weight:bold;">Lr</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[266]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Rutherfordium" title="Rutherfordium"><span title="Rf, rutherfordium" style="background-color: #99ccff; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Ruther­fordium</span><span style="color: #000000; display:block;">104</span><span style="display:block; font-size:112%; font-weight:bold;">Rf</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[267]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Dubnium" title="Dubnium"><span title="Db, dubnium" style="background-color: #99ccff; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Dub­nium</span><span style="color: #000000; display:block;">105</span><span style="display:block; font-size:112%; font-weight:bold;">Db</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[268]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Seaborgium" title="Seaborgium"><span title="Sg, seaborgium" style="background-color: #99ccff; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Sea­borgium</span><span style="color: #000000; display:block;">106</span><span style="display:block; font-size:112%; font-weight:bold;">Sg</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[269]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Bohrium" title="Bohrium"><span title="Bh, bohrium" style="background-color: #99ccff; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Bohr­ium</span><span style="color: #000000; display:block;">107</span><span style="display:block; font-size:112%; font-weight:bold;">Bh</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[270]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Hassium" title="Hassium"><span title="Hs, hassium" style="background-color: #99ccff; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Has­sium</span><span style="color: #000000; display:block;">108</span><span style="display:block; font-size:112%; font-weight:bold;">Hs</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[269]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Meitnerium" title="Meitnerium"><span title="Mt, meitnerium" style="background-color: #99ccff; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Meit­nerium</span><span style="color: #000000; display:block;">109</span><span style="display:block; font-size:112%; font-weight:bold;">Mt</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[278]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Darmstadtium" title="Darmstadtium"><span title="Ds, darmstadtium" style="background-color: #99ccff; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Darm­stadtium</span><span style="color: #000000; display:block;">110</span><span style="display:block; font-size:112%; font-weight:bold;">Ds</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[281]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Roentgenium" title="Roentgenium"><span title="Rg, roentgenium" style="background-color: #99ccff; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Roent­genium</span><span style="color: #000000; display:block;">111</span><span style="display:block; font-size:112%; font-weight:bold;">Rg</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[282]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Copernicium" title="Copernicium"><span title="Cn, copernicium" style="background-color: #99ccff; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Coper­nicium</span><span style="color: #000000; display:block;">112</span><span style="display:block; font-size:112%; font-weight:bold;">Cn</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[285]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Nihonium" title="Nihonium"><span title="Nh, nihonium" style="background-color: #fdff8c; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Nihon­ium</span><span style="color: #000000; display:block;">113</span><span style="display:block; font-size:112%; font-weight:bold;">Nh</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[286]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Flerovium" title="Flerovium"><span title="Fl, flerovium" style="background-color: #fdff8c; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Flerov­ium</span><span style="color: #000000; display:block;">114</span><span style="display:block; font-size:112%; font-weight:bold;">Fl</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[289]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Moscovium" title="Moscovium"><span title="Mc, moscovium" style="background-color: #fdff8c; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Moscov­ium</span><span style="color: #000000; display:block;">115</span><span style="display:block; font-size:112%; font-weight:bold;">Mc</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[290]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Livermorium" title="Livermorium"><span title="Lv, livermorium" style="background-color: #fdff8c; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Liver­morium</span><span style="color: #000000; display:block;">116</span><span style="display:block; font-size:112%; font-weight:bold;">Lv</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[293]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Tennessine" title="Tennessine"><span title="Ts, tennessine" style="background-color: #fdff8c; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Tenness­ine</span><span style="color: #000000; display:block;">117</span><span style="display:block; font-size:112%; font-weight:bold;">Ts</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[294]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Oganesson" title="Oganesson"><span title="Og, oganesson" style="background-color: #fdff8c; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Oga­nesson</span><span style="color: #000000; display:block;">118</span><span style="display:block; font-size:112%; font-weight:bold;">Og</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[294]</span></span></a></span> </td></tr> <tr> <td colspan="20" style="height:1.4em;"> </td></tr> <tr> <td> </td> <td> </td> <td> </td> <td style="text-align:center; vertical-align:middle; background:#9bff99"><span class="skin-invert-image" typeof="mw:File"><span><img alt="1 asterisk" src="//upload.wikimedia.org/wikipedia/commons/thumb/4/49/Asterisks_one.svg/16px-Asterisks_one.svg.png" decoding="async" width="16" height="15" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/49/Asterisks_one.svg/24px-Asterisks_one.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/49/Asterisks_one.svg/32px-Asterisks_one.svg.png 2x" data-file-width="106" data-file-height="98" /></span></span> </td> <td><span class="nounderlines"><a href="/wiki/Lanthanum" title="Lanthanum"><span title="La, lanthanum" style="background-color: #9bff99; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Lan­thanum</span><span style="color: #000000; display:block;">57</span><span style="display:block; font-size:112%; font-weight:bold;">La</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002138910000000000♠"></span>138.91</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Cerium" title="Cerium"><span title="Ce, cerium" style="background-color: #9bff99; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Cerium</span><span style="color: #000000; display:block;">58</span><span style="display:block; font-size:112%; font-weight:bold;">Ce</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002140120000000000♠"></span>140.12</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Praseodymium" title="Praseodymium"><span title="Pr, praseodymium" style="background-color: #9bff99; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Praseo­dymium</span><span style="color: #000000; display:block;">59</span><span style="display:block; font-size:112%; font-weight:bold;">Pr</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002140910000000000♠"></span>140.91</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Neodymium" title="Neodymium"><span title="Nd, neodymium" style="background-color: #9bff99; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Neo­dymium</span><span style="color: #000000; display:block;">60</span><span style="display:block; font-size:112%; font-weight:bold;">Nd</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002144240000000000♠"></span>144.24</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Promethium" title="Promethium"><span title="Pm, promethium" style="background-color: #9bff99; border-top: 2px dashed #6e6e8e; border-bottom: 2px dashed #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Prome­thium</span><span style="color: #000000; display:block;">61</span><span style="display:block; font-size:112%; font-weight:bold;">Pm</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[145]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Samarium" title="Samarium"><span title="Sm, samarium" style="background-color: #9bff99; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Sama­rium</span><span style="color: #000000; display:block;">62</span><span style="display:block; font-size:112%; font-weight:bold;">Sm</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002150360000000000♠"></span>150.36</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Europium" title="Europium"><span title="Eu, europium" style="background-color: #9bff99; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Europ­ium</span><span style="color: #000000; display:block;">63</span><span style="display:block; font-size:112%; font-weight:bold;">Eu</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002151960000000000♠"></span>151.96</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Gadolinium" title="Gadolinium"><span title="Gd, gadolinium" style="background-color: #9bff99; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Gadolin­ium</span><span style="color: #000000; display:block;">64</span><span style="display:block; font-size:112%; font-weight:bold;">Gd</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002157250000000000♠"></span>157.25</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Terbium" title="Terbium"><span title="Tb, terbium" style="background-color: #9bff99; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Ter­bium</span><span style="color: #000000; display:block;">65</span><span style="display:block; font-size:112%; font-weight:bold;">Tb</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002158930000000000♠"></span>158.93</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Dysprosium" title="Dysprosium"><span title="Dy, dysprosium" style="background-color: #9bff99; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Dyspro­sium</span><span style="color: #000000; display:block;">66</span><span style="display:block; font-size:112%; font-weight:bold;">Dy</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002162500000000000♠"></span>162.50</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Holmium" title="Holmium"><span title="Ho, holmium" style="background-color: #9bff99; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Hol­mium</span><span style="color: #000000; display:block;">67</span><span style="display:block; font-size:112%; font-weight:bold;">Ho</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002164930000000000♠"></span>164.93</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Erbium" title="Erbium"><span title="Er, erbium" style="background-color: #9bff99; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Erbium</span><span style="color: #000000; display:block;">68</span><span style="display:block; font-size:112%; font-weight:bold;">Er</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002167260000000000♠"></span>167.26</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Thulium" title="Thulium"><span title="Tm, thulium" style="background-color: #9bff99; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Thulium</span><span style="color: #000000; display:block;">69</span><span style="display:block; font-size:112%; font-weight:bold;">Tm</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002168930000000000♠"></span>168.93</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Ytterbium" title="Ytterbium"><span title="Yb, ytterbium" style="background-color: #9bff99; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Ytter­bium</span><span style="color: #000000; display:block;">70</span><span style="display:block; font-size:112%; font-weight:bold;">Yb</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002173050000000000♠"></span>173.05</span></span></span></a></span> </td> <td> </td> <td>  </td></tr> <tr> <td colspan="3"> </td> <td style="text-align:center; vertical-align:middle; background:#9bff99"><span class="skin-invert-image" typeof="mw:File"><span><img alt="1 asterisk" src="//upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Asterisks_2_%28vertical%29.svg/16px-Asterisks_2_%28vertical%29.svg.png" decoding="async" width="16" height="15" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Asterisks_2_%28vertical%29.svg/24px-Asterisks_2_%28vertical%29.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Asterisks_2_%28vertical%29.svg/32px-Asterisks_2_%28vertical%29.svg.png 2x" data-file-width="106" data-file-height="98" /></span></span> </td> <td><span class="nounderlines"><a href="/wiki/Actinium" title="Actinium"><span title="Ac, actinium" style="background-color: #9bff99; border-top: 2px dashed #6e6e8e; border-bottom: 2px dashed #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Actin­ium</span><span style="color: #000000; display:block;">89</span><span style="display:block; font-size:112%; font-weight:bold;">Ac</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[227]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Thorium" title="Thorium"><span title="Th, thorium" style="background-color: #9bff99; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Thor­ium</span><span style="color: #000000; display:block;">90</span><span style="display:block; font-size:112%; font-weight:bold;">Th</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002232040000000000♠"></span>232.04</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Protactinium" title="Protactinium"><span title="Pa, protactinium" style="background-color: #9bff99; border-top: 2px dashed #6e6e8e; border-bottom: 2px dashed #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Protac­tinium</span><span style="color: #000000; display:block;">91</span><span style="display:block; font-size:112%; font-weight:bold;">Pa</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002231040000000000♠"></span>231.04</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Uranium" title="Uranium"><span title="U , uranium" style="background-color: #9bff99; border-top: 2px solid #6e6e8e; border-bottom: 2px solid #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Ura­nium</span><span style="color: #000000; display:block;">92</span><span style="display:block; font-size:112%; font-weight:bold;">U</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​<span class="nowrap"><span data-sort-value="7002238030000000000♠"></span>238.03</span></span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Neptunium" title="Neptunium"><span title="Np, neptunium" style="background-color: #9bff99; border-top: 2px dashed #6e6e8e; border-bottom: 2px dashed #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Neptu­nium</span><span style="color: #000000; display:block;">93</span><span style="display:block; font-size:112%; font-weight:bold;">Np</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[237]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Plutonium" title="Plutonium"><span title="Pu, plutonium" style="background-color: #9bff99; border-top: 2px dashed #6e6e8e; border-bottom: 2px dashed #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Pluto­nium</span><span style="color: #000000; display:block;">94</span><span style="display:block; font-size:112%; font-weight:bold;">Pu</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[244]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Americium" title="Americium"><span title="Am, americium" style="background-color: #9bff99; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Ameri­cium</span><span style="color: #000000; display:block;">95</span><span style="display:block; font-size:112%; font-weight:bold;">Am</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[243]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Curium" title="Curium"><span title="Cm, curium" style="background-color: #9bff99; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Curium</span><span style="color: #000000; display:block;">96</span><span style="display:block; font-size:112%; font-weight:bold;">Cm</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[247]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Berkelium" title="Berkelium"><span title="Bk, berkelium" style="background-color: #9bff99; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Berkel­ium</span><span style="color: #000000; display:block;">97</span><span style="display:block; font-size:112%; font-weight:bold;">Bk</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[247]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Californium" title="Californium"><span title="Cf, californium" style="background-color: #9bff99; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Califor­nium</span><span style="color: #000000; display:block;">98</span><span style="display:block; font-size:112%; font-weight:bold;">Cf</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[251]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Einsteinium" title="Einsteinium"><span title="Es, einsteinium" style="background-color: #9bff99; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Einstei­nium</span><span style="color: #000000; display:block;">99</span><span style="display:block; font-size:112%; font-weight:bold;">Es</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[252]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Fermium" title="Fermium"><span title="Fm, fermium" style="background-color: #9bff99; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Fer­mium</span><span style="color: #000000; display:block;">100</span><span style="display:block; font-size:112%; font-weight:bold;">Fm</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[257]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Mendelevium" title="Mendelevium"><span title="Md, mendelevium" style="background-color: #9bff99; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Mende­levium</span><span style="color: #000000; display:block;">101</span><span style="display:block; font-size:112%; font-weight:bold;">Md</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[258]</span></span></a></span> </td> <td><span class="nounderlines"><a href="/wiki/Nobelium" title="Nobelium"><span title="No, nobelium" style="background-color: #9bff99; border-top: 2px dotted #6e6e8e; border-bottom: 2px dotted #6e6e8e; display: block; line-height: 1.1em; overflow: hidden; padding: 2px 0; text-align: center; vertical-align: bottom;"><span style="display:block; color:black; font-size:95%; height:2.2em; line-height:1.1em; vertical-align:top;">Nobel­ium</span><span style="color: #000000; display:block;">102</span><span style="display:block; font-size:112%; font-weight:bold;">No</span><span style="display:block; color:black; font-size:95%; height:1.1em; line-height:1.1em;">​[259]</span></span></a></span> </td> <td> </td></tr></tbody></table> <div id="Periodic_table_legend_for_category"></div> <div role="presentation" id="periodic-table-legend" style="border: 1px solid #a2a9b1; width:100%; line-height:120%; text-align:center; vertical-align:top; background:#f8f8f8; margin:0; font-size:100%;"><div style="padding:0.3em;"> </div><div style="border-top: 1px solid #a2a9b1;padding:0.3em;"> <span style="text-align:center;display:inline-block; width:8em; border-top:2px solid #6e6e8e; border-bottom:2px solid #6e6e8e; background:#e0e0e0;"><a href="/wiki/Primordial_nuclide" title="Primordial nuclide">Primordial</a></span> <span style="text-align:center;display:inline-block; width:8em; border-top:2px dashed #6e6e8e; border-bottom:2px dashed #6e6e8e; background:#e0e0e0;"> <a href="/wiki/Trace_radioisotope" title="Trace radioisotope"><span class="nowrap">From decay</span></a></span> <span style="text-align:center;display:inline-block; width:8em; border-top:2px dotted #6e6e8e; border-bottom:2px dotted #6e6e8e; background:#e0e0e0;"> <a href="/wiki/Synthetic_element" title="Synthetic element">Synthetic</a></span> <span class="nowrap"><b>Border</b> shows natural occurrence of the element</span> </div><div style="border-top: 1px solid #a2a9b1;padding:0.3em;"> <div style="text-align:left"><span class="nowrap"><b><a href="/wiki/Standard_atomic_weight#Published_values" title="Standard atomic weight">Standard atomic weight</a></b> <i>A</i><sub>r, std</sub>(E)<sup id="cite_ref-CIAAW2013_3-0" class="reference"><a href="#cite_note-CIAAW2013-3"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup></span><style data-mw-deduplicate="TemplateStyles:r1126788409">.mw-parser-output .plainlist ol,.mw-parser-output .plainlist ul{line-height:inherit;list-style:none;margin:0;padding:0}.mw-parser-output .plainlist ol li,.mw-parser-output .plainlist ul li{margin-bottom:0}</style><div class="plainlist" style="display: inline-block;"> <ul><li>Ca: <span class="nowrap"><span data-sort-value="7001400780000000000♠"></span>40.078</span> — Abridged value (uncertainty omitted here)<sup id="cite_ref-CIAAW2021_4-0" class="reference"><a href="#cite_note-CIAAW2021-4"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup></li> <li>Po: [209] — <a href="/wiki/Mass_number" title="Mass number">mass number</a> of the most stable isotope</li></ul></div></div> </div><div style="border-top: 1px solid #a2a9b1;padding:0.3em;"> <table style="width:100%; line-height:1.2em; table-layout:fixed; overflow:hidden; text-align:center;"> <tbody><tr> <td style="padding:0 1px; background:#ff9999;"><a href="/wiki/S-block" class="mw-redirect" title="S-block">s-block</a> </td> <td style="padding:0 1px; background:#9bff99;"><a href="/wiki/F-block" class="mw-redirect" title="F-block">f-block</a> </td> <td style="padding:0 1px; background:#99ccff;"><a href="/wiki/D-block" class="mw-redirect" title="D-block">d-block</a> </td> <td style="padding:0 1px; background:#fdff8c;"><a href="/wiki/P-block" class="mw-redirect" title="P-block">p-block</a> </td></tr></tbody></table> </div> </div> </div></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Atomic-orbital-clouds_spdf_m0.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c4/Atomic-orbital-clouds_spdf_m0.png/330px-Atomic-orbital-clouds_spdf_m0.png" decoding="async" width="330" height="330" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c4/Atomic-orbital-clouds_spdf_m0.png/495px-Atomic-orbital-clouds_spdf_m0.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c4/Atomic-orbital-clouds_spdf_m0.png/660px-Atomic-orbital-clouds_spdf_m0.png 2x" data-file-width="1600" data-file-height="1600" /></a><figcaption>3D views of some <a href="/wiki/Hydrogen-like_atom" title="Hydrogen-like atom">hydrogen-like</a> <a href="/wiki/Atomic_orbital" title="Atomic orbital">atomic orbitals</a> showing probability density and phase (g orbitals and higher are not shown)</figcaption></figure> <p>Each chemical element has a unique <a href="/wiki/Atomic_number" title="Atomic number">atomic number</a> (<i>Z</i>— for "Zahl", German for "number") representing the number of <a href="/wiki/Proton" title="Proton">protons</a> in its <a href="/wiki/Atomic_nucleus" title="Atomic nucleus">nucleus</a>.<sup id="cite_ref-neutronium_5-0" class="reference"><a href="#cite_note-neutronium-5"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> Each distinct atomic number therefore corresponds to a class of atom: these classes are called the <a href="/wiki/Chemical_element" title="Chemical element">chemical elements</a>.<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> The chemical elements are what the periodic table classifies and organizes. <a href="/wiki/Hydrogen" title="Hydrogen">Hydrogen</a> is the element with atomic number 1; <a href="/wiki/Helium" title="Helium">helium</a>, atomic number 2; <a href="/wiki/Lithium" title="Lithium">lithium</a>, atomic number 3; and so on. Each of these names can be further abbreviated by a one- or two-letter <a href="/wiki/Chemical_symbol" title="Chemical symbol">chemical symbol</a>; those for hydrogen, helium, and lithium are respectively H, He, and Li.<sup id="cite_ref-IUPAC-redbook_7-0" class="reference"><a href="#cite_note-IUPAC-redbook-7"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> Neutrons do not affect the atom's chemical identity, but do affect its weight. Atoms with the same number of protons but different numbers of neutrons are called <a href="/wiki/Isotope" title="Isotope">isotopes</a> of the same chemical element.<sup id="cite_ref-IUPAC-redbook_7-1" class="reference"><a href="#cite_note-IUPAC-redbook-7"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> Naturally occurring elements usually occur as mixes of different isotopes; since each isotope usually occurs with a characteristic abundance, naturally occurring elements have well-defined <a href="/wiki/Atomic_weight" class="mw-redirect" title="Atomic weight">atomic weights</a>, defined as the average mass of a naturally occurring atom of that element.<sup id="cite_ref-ciaaw_8-0" class="reference"><a href="#cite_note-ciaaw-8"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> All elements have multiple <a href="/wiki/Isotope" title="Isotope">isotopes</a>, variants with the same number of protons but different numbers of <a href="/wiki/Neutron" title="Neutron">neutrons</a>. For example, <a href="/wiki/Carbon" title="Carbon">carbon</a> has three naturally occurring isotopes: all of its <a href="/wiki/Atom" title="Atom">atoms</a> have six protons and most have six neutrons as well, but about one per cent have seven neutrons, and a very small fraction have eight neutrons. Isotopes are never separated in the periodic table; they are always grouped together under a single element. When atomic mass is shown, it is usually the weighted average of naturally occurring isotopes; but if no isotopes occur naturally in significant quantities, the mass of the most stable isotope usually appears, often in parentheses.<sup id="cite_ref-Greenwood_9-0" class="reference"><a href="#cite_note-Greenwood-9"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p><p>In the standard periodic table, the elements are listed in order of increasing atomic number. A new row (<a href="/wiki/Period_(periodic_table)" title="Period (periodic table)"><i>period</i></a>) is started when a new <a href="/wiki/Electron_shell" title="Electron shell">electron shell</a> has its first <a href="/wiki/Electron" title="Electron">electron</a>. Columns (<a href="/wiki/Group_(periodic_table)" title="Group (periodic table)"><i>groups</i></a>) are determined by the <a href="/wiki/Electron_configuration" title="Electron configuration">electron configuration</a> of the atom; elements with the same number of electrons in a particular subshell fall into the same columns (e.g. <a href="/wiki/Oxygen" title="Oxygen">oxygen</a>, <a href="/wiki/Sulfur" title="Sulfur">sulfur</a>, and <a href="/wiki/Selenium" title="Selenium">selenium</a> are in the same column because they all have four electrons in the outermost p-subshell). Elements with similar chemical properties generally fall into the same group in the periodic table, although in the f-block, and to some respect in the d-block, the elements in the same period tend to have similar properties, as well. Thus, it is relatively easy to predict the chemical properties of an element if one knows the properties of the elements around it.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> </p><p>Today, 118 elements are known, the first 94 of which are known to occur naturally on Earth at present.<sup id="cite_ref-ThorntonBurdette_11-0" class="reference"><a href="#cite_note-ThorntonBurdette-11"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-transuranium_1-1" class="reference"><a href="#cite_note-transuranium-1"><span class="cite-bracket">[</span>a<span class="cite-bracket">]</span></a></sup> The remaining 24, americium to oganesson (95–118), occur only when synthesized in laboratories. Of the 94 naturally occurring elements, 83 are <a href="/wiki/Primordial_element" class="mw-redirect" title="Primordial element">primordial</a> and 11 occur only in decay chains of primordial elements. A few of the latter are so rare that they were not discovered in nature, but were synthesized in the laboratory before it was determined that they do exist in nature after all: <a href="/wiki/Technetium" title="Technetium">technetium</a> (element 43), <a href="/wiki/Promethium" title="Promethium">promethium</a> (element 61), <a href="/wiki/Astatine" title="Astatine">astatine</a> (element 85), <a href="/wiki/Neptunium" title="Neptunium">neptunium</a> (element 93), and <a href="/wiki/Plutonium" title="Plutonium">plutonium</a> (element 94).<sup id="cite_ref-emsley_13-1" class="reference"><a href="#cite_note-emsley-13"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> No element heavier than <a href="/wiki/Einsteinium" title="Einsteinium">einsteinium</a> (element 99) has ever been observed in macroscopic quantities in its pure form, nor has <a href="/wiki/Astatine" title="Astatine">astatine</a>; <a href="/wiki/Francium" title="Francium">francium</a> (element 87) has been only photographed in the form of <a href="/wiki/Light" title="Light">light</a> emitted from microscopic quantities (300,000 atoms).<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> Of the 94 natural elements, eighty have a stable isotope and one more (<a href="/wiki/Bismuth" title="Bismuth">bismuth</a>) has an almost-stable isotope (with a <a href="/wiki/Half-life" title="Half-life">half-life</a> of 2.01×10<sup>19</sup> years, over a billion times the <a href="/wiki/Age_of_the_universe" title="Age of the universe">age of the universe</a>).<sup id="cite_ref-Bi209alpha2_16-0" class="reference"><a href="#cite_note-Bi209alpha2-16"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>b<span class="cite-bracket">]</span></a></sup> Two more, <a href="/wiki/Thorium" title="Thorium">thorium</a> and <a href="/wiki/Uranium" title="Uranium">uranium</a>, have isotopes undergoing <a href="/wiki/Radioactive_decay" title="Radioactive decay">radioactive decay</a> with a half-life comparable to the <a href="/wiki/Age_of_the_Earth" class="mw-redirect" title="Age of the Earth">age of the Earth</a>. The stable elements plus bismuth, thorium, and uranium make up the 83 <a href="/wiki/Primordial_nuclide" title="Primordial nuclide">primordial</a> elements that survived from the Earth's formation.<sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>c<span class="cite-bracket">]</span></a></sup> The remaining eleven natural elements decay quickly enough that their continued trace occurrence rests primarily on being constantly regenerated as intermediate products of the decay of thorium and uranium.<sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>d<span class="cite-bracket">]</span></a></sup> All 24 known artificial elements are radioactive.<sup id="cite_ref-IUPAC-redbook_7-2" class="reference"><a href="#cite_note-IUPAC-redbook-7"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Group_names_and_numbers">Group names and numbers</h3></div> <p>Under an international naming convention, the groups are numbered numerically from 1 to 18 from the leftmost column (the alkali metals) to the rightmost column (the noble gases). The f-block groups are ignored in this numbering.<sup id="cite_ref-IUPAC_26-0" class="reference"><a href="#cite_note-IUPAC-26"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> Groups can also be named by their first element, e.g. the "scandium group" for group 3.<sup id="cite_ref-IUPAC_26-1" class="reference"><a href="#cite_note-IUPAC-26"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> Previously, groups were known by <a href="/wiki/Roman_numerals" title="Roman numerals">Roman numerals</a>. In the <a href="/wiki/United_States" title="United States">United States</a>, the Roman numerals were followed by either an "A" if the group was in the <a href="/wiki/S-block" class="mw-redirect" title="S-block">s-</a> or <a href="/wiki/P-block" class="mw-redirect" title="P-block">p-block</a>, or a "B" if the group was in the <a href="/wiki/D-block" class="mw-redirect" title="D-block">d-block</a>. The Roman numerals used correspond to the last digit of today's naming convention (e.g. the <a href="/wiki/Group_4_element" title="Group 4 element">group 4 elements</a> were group IVB, and the <a href="/wiki/Carbon_group" title="Carbon group">group 14 elements</a> were group IVA). In <a href="/wiki/Europe" title="Europe">Europe</a>, the lettering was similar, except that "A" was used for groups 1 through 7, and "B" was used for groups 11 through 17. In addition, groups 8, 9 and 10 used to be treated as one triple-sized group, known collectively in both notations as group VIII. In 1988, the new <a href="/wiki/IUPAC" class="mw-redirect" title="IUPAC">IUPAC</a> (International Union of Pure and Applied Chemistry) naming system (1–18) was put into use, and the old group names (I–VIII) were deprecated.<sup id="cite_ref-Fluck_27-0" class="reference"><a href="#cite_note-Fluck-27"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-collapsible uncollapsed" style="background:#f8f8f8; font-size:85%; border:1px solid #a9a9a9; width:100%; margin:0 auto; padding:2px; text-align:center; vertical-align:top;"> <div style="background:#d8d8d8; padding:2px 4px;font-weight:bold;"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-collapse navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Periodic_table_(group_names)" title="Template:Periodic table (group names)"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Periodic_table_(group_names)" class="mw-redirect" title="Template talk:Periodic table (group names)"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Periodic_table_(group_names)" title="Special:EditPage/Template:Periodic table (group names)"><abbr title="Edit this template">e</abbr></a></li></ul></div><div class="navbar-ct-mini">Groups in the <a class="mw-selflink selflink">periodic table</a></div></div><div class="mw-collapsible-content"> <table border="0" cellpadding="0" cellspacing="2" style="display:block;overflow:auto;width:100%;text-align:center; max-width:1300px; margin:0; padding:0;"> <tbody><tr style="line-height:120%; vertical-align:top;"> <td style="text-align:left;"><a href="/wiki/Group_(periodic_table)" title="Group (periodic table)">IUPAC group</a> </td> <th style="background:#e1e1e1;"><a href="/wiki/Group_1_element" class="mw-redirect" title="Group 1 element">1</a><sup class="plainlinks nourlexpansion citation" id="ref_group1"><a href="#endnote_group1">a</a></sup> </th> <th style="background:#f1f1f1;"><a href="/wiki/Alkaline_earth_metal" title="Alkaline earth metal">2</a> </th> <th style="background:#e1e1e1;">—<sup class="plainlinks nourlexpansion citation" id="ref_f-block_groups"><a href="#endnote_f-block_groups">b</a></sup> </th> <th style="background:#f1f1f1;"><a href="/wiki/Group_3_element" title="Group 3 element">3</a><sup class="plainlinks nourlexpansion citation" id="ref_ScYLu"><a href="#endnote_ScYLu">c</a></sup> </th> <th style="background:#e1e1e1;"><a href="/wiki/Group_4_element" title="Group 4 element">4</a> </th> <th style="background:#f1f1f1;"><a href="/wiki/Group_5_element" title="Group 5 element">5</a> </th> <th style="background:#e1e1e1;"><a href="/wiki/Group_6_element" title="Group 6 element">6</a> </th> <th style="background:#f1f1f1;"><a href="/wiki/Group_7_element" title="Group 7 element">7</a> </th> <th style="background:#e1e1e1;"><a href="/wiki/Group_8_element" title="Group 8 element">8</a> </th> <th style="background:#f1f1f1;"><a href="/wiki/Group_9_element" title="Group 9 element">9</a> </th> <th style="background:#e1e1e1;"><a href="/wiki/Group_10_element" title="Group 10 element">10</a> </th> <th style="background:#f1f1f1;"><a href="/wiki/Group_11_element" title="Group 11 element">11</a> </th> <th style="background:#e1e1e1;"><a href="/wiki/Group_12_element" title="Group 12 element">12</a> </th> <th style="background:#f1f1f1;"><a href="/wiki/Boron_group" title="Boron group">13</a> </th> <th style="background:#e1e1e1;"><a href="/wiki/Carbon_group" title="Carbon group">14</a> </th> <th style="background:#f1f1f1;"><a href="/wiki/Pnictogen" title="Pnictogen">15</a> </th> <th style="background:#e1e1e1;"><a href="/wiki/Chalcogen" title="Chalcogen">16</a> </th> <th style="background:#f1f1f1;"><a href="/wiki/Halogen" title="Halogen">17</a> </th> <th style="background:#e1e1e1;"><a href="/wiki/Noble_gas" title="Noble gas">18</a> </th></tr> <tr style="line-height:120%; vertical-align:top;"> <td style="vertical-align:top; text-align:left;"><a href="/wiki/Dmitri_Mendeleev#Periodic_table" title="Dmitri Mendeleev">Mendeleev</a> <small>(I–VIII)</small> </td> <td style="background:#e1e1e1;">I<span style="visibility:hidden">A</span> </td> <td style="background:#f1f1f1;">II<span style="visibility:hidden">A</span> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;">III<span style="visibility:hidden">B</span> </td> <td style="background:#e1e1e1;">IV<span style="visibility:hidden">B</span> </td> <td style="background:#f1f1f1;">V<span style="visibility:hidden">B</span> </td> <td style="background:#e1e1e1;">VI<span style="visibility:hidden">B</span> </td> <td style="background:#f1f1f1;">VII<span style="visibility:hidden">B</span> </td> <td colspan="3" style="background:#e1e1e1; border-top:1px solid #b8b8b8; text-align:center;">VIII<span style="visibility:hidden;color:transparent;">B</span> </td> <td style="background:#f1f1f1;">I<span style="visibility:hidden">B</span> </td> <td style="background:#e1e1e1;">II<span style="visibility:hidden">B</span> </td> <td style="background:#f1f1f1;">III<span style="visibility:hidden">B</span> </td> <td style="background:#e1e1e1;">IV<span style="visibility:hidden">B</span> </td> <td style="background:#f1f1f1;">V<span style="visibility:hidden">B</span> </td> <td style="background:#e1e1e1;">VI<span style="visibility:hidden">B</span> </td> <td style="background:#f1f1f1;">VII<span style="visibility:hidden">B</span> </td> <td style="background:#e1e1e1;"><sup class="plainlinks nourlexpansion citation" id="ref_group0"><a href="#endnote_group0">d</a></sup> </td></tr> <tr style="line-height:120%; vertical-align:top;"> <td style="text-align:left; vertical-align:top;"><a href="/wiki/Group_(periodic_table)#CAS_and_old_IUPAC" title="Group (periodic table)">CAS</a> <small>(US, A-B-A)</small> </td> <td style="background:#e1e1e1;">IA </td> <td style="background:#f1f1f1;">IIA </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;">IIIB </td> <td style="background:#e1e1e1;">IVB </td> <td style="background:#f1f1f1;">VB </td> <td style="background:#e1e1e1;">VIB </td> <td style="background:#f1f1f1;">VIIB </td> <td colspan="3" style="background:#e1e1e1; border-top:1px solid #b8b8b8;">VIIIB </td> <td style="background:#f1f1f1;">IB </td> <td style="background:#e1e1e1;">IIB </td> <td style="background:#f1f1f1;">IIIA </td> <td style="background:#e1e1e1;">IVA </td> <td style="background:#f1f1f1;">VA </td> <td style="background:#e1e1e1;">VIA </td> <td style="background:#f1f1f1;">VIIA </td> <td style="background:#e1e1e1;">VIIIA </td></tr> <tr style="line-height:120%; vertical-align:top;"> <td style="text-align:left;"><a href="/wiki/Group_(periodic_table)#CAS_and_old_IUPAC" title="Group (periodic table)">Old IUPAC</a> <small>(Europe, A-B)</small> </td> <td style="background:#e1e1e1;">IA </td> <td style="background:#f1f1f1;">IIA </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;">IIIA </td> <td style="background:#e1e1e1;">IVA </td> <td style="background:#f1f1f1;">VA </td> <td style="background:#e1e1e1;">VIA </td> <td style="background:#f1f1f1;">VIIA </td> <td colspan="3" style="background:#e1e1e1; border-top:1px solid #b8b8b8;">VIII<span style="visibility:hidden;color:transparent;">B</span> </td> <td style="background:#f1f1f1;">IB </td> <td style="background:#e1e1e1;">IIB </td> <td style="background:#f1f1f1;">IIIB </td> <td style="background:#e1e1e1;">IVB </td> <td style="background:#f1f1f1;">VB </td> <td style="background:#e1e1e1;">VIB </td> <td style="background:#f1f1f1;">VIIB </td> <td style="background:#e1e1e1; font-size:95%;">0 </td></tr> <tr style="line-height:120%; vertical-align:top;"> <td style="text-align:left;"><a href="/wiki/Trivial_name" title="Trivial name">Trivial name</a><sup class="plainlinks nourlexpansion citation" id="ref_IUPAC"><a href="#endnote_IUPAC">r</a></sup> </td> <td style="background:#e1e1e1;">H and <a href="/wiki/Alkali_metal" title="Alkali metal">alkali metals</a> </td> <td style="background:#f1f1f1;"><a href="/wiki/Alkaline_earth_metal" title="Alkaline earth metal">alkaline earth metals</a> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"><a href="/wiki/Boron_group" title="Boron group">triels</a> </td> <td style="background:#e1e1e1;"><a href="/wiki/Carbon_group" title="Carbon group">tetrels</a> </td> <td style="background:#f1f1f1;"><a href="/wiki/Pnictogens" class="mw-redirect" title="Pnictogens">pnicto­gens</a> </td> <td style="background:#e1e1e1;"><a href="/wiki/Chalcogens" class="mw-redirect" title="Chalcogens">chal­co­gens</a> </td> <td style="background:#f1f1f1;"><a href="/wiki/Halogens" class="mw-redirect" title="Halogens">halo­gens</a> </td> <td style="background:#e1e1e1;"><a href="/wiki/Noble_gases" class="mw-redirect" title="Noble gases">noble gases</a> </td></tr> <tr style="line-height:120%; vertical-align:top;"> <td style="text-align:left;">Name by element<sup class="plainlinks nourlexpansion citation" id="ref_IUPAC"><a href="#endnote_IUPAC">r</a></sup> </td> <td style="background:#e1e1e1;">lith­ium group </td> <td style="background:#f1f1f1;">beryl­lium group </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;">scan­dium group </td> <td style="background:#e1e1e1;">titan­ium group </td> <td style="background:#f1f1f1;">vana­dium group </td> <td style="background:#e1e1e1;">chro­mium group </td> <td style="background:#f1f1f1;">man­ga­nese group </td> <td style="background:#e1e1e1;">iron group </td> <td style="background:#f1f1f1;">co­balt group </td> <td style="background:#e1e1e1;">nickel group </td> <td style="background:#f1f1f1;">cop­per group </td> <td style="background:#e1e1e1;">zinc group </td> <td style="background:#f1f1f1;">boron group </td> <td style="background:#e1e1e1;">car­bon group </td> <td style="background:#f1f1f1;">nitro­gen group </td> <td style="background:#e1e1e1;">oxy­gen group </td> <td style="background:#f1f1f1;">fluor­ine group </td> <td style="background:#e1e1e1;">helium <i>or</i> neon group </td></tr> <tr> <td style="text-align:right; padding-right:1em;"><a href="/wiki/Period_1_element" title="Period 1 element">Period 1</a> </td> <td title="<span class=" class="nowrap" style="text-align:center; color:#000000; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Hydrogen" title="Hydrogen"><span style="display:block"><span class="nowrap"> </span>H<span class="nowrap"> </span></span></a></span> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td title="He, Helium" style="text-align:center; color:#000000; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Helium" title="Helium"><span style="display:block">He</span></a></span> </td></tr> <tr> <td style="text-align:right; padding-right:1em;"><a href="/wiki/Period_2_element" title="Period 2 element">Period 2</a> </td> <td title="Li, Lithium" style="text-align:center; color:#000000; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Lithium" title="Lithium"><span style="display:block">Li</span></a></span> </td> <td title="Be, Beryllium" style="text-align:center; color:#000000; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Beryllium" title="Beryllium"><span style="display:block">Be</span></a></span> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td title="B, Boron" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Boron" title="Boron"><span style="display:block">B</span></a></span> </td> <td title="C, Carbon" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Carbon" title="Carbon"><span style="display:block">C</span></a></span> </td> <td title="N, Nitrogen" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Nitrogen" title="Nitrogen"><span style="display:block">N</span></a></span> </td> <td title="O, Oxygen" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Oxygen" title="Oxygen"><span style="display:block">O</span></a></span> </td> <td title="F, Fluorine" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Fluorine" title="Fluorine"><span style="display:block">F</span></a></span> </td> <td title="Ne, Neon" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Neon" title="Neon"><span style="display:block">Ne</span></a></span> </td></tr> <tr> <td style="text-align:right; padding-right:1em;"><a href="/wiki/Period_3_element" title="Period 3 element">Period 3</a> </td> <td title="Na, Sodium" style="text-align:center; color:#000000; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Sodium" title="Sodium"><span style="display:block">Na</span></a></span> </td> <td title="Mg, Magnesium" style="text-align:center; color:#000000; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Magnesium" title="Magnesium"><span style="display:block">Mg</span></a></span> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td style="background:#f1f1f1;"> </td> <td style="background:#e1e1e1;"> </td> <td title="Al, Aluminium" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Aluminium" title="Aluminium"><span style="display:block">Al</span></a></span> </td> <td title="Si, Silicon" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Silicon" title="Silicon"><span style="display:block">Si</span></a></span> </td> <td title="P, Phosphorus" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Phosphorus" title="Phosphorus"><span style="display:block">P</span></a></span> </td> <td title="S, Sulfur" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Sulfur" title="Sulfur"><span style="display:block">S</span></a></span> </td> <td title="Cl, Chlorine" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Chlorine" title="Chlorine"><span style="display:block">Cl</span></a></span> </td> <td title="Ar, Argon" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Argon" title="Argon"><span style="display:block">Ar</span></a></span> </td></tr> <tr> <td style="text-align:right; padding-right:1em;"><a href="/wiki/Period_4_element" title="Period 4 element">Period 4</a> </td> <td title="K, Potassium" style="text-align:center; color:#000000; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Potassium" title="Potassium"><span style="display:block">K</span></a></span> </td> <td title="Ca, Calcium" style="text-align:center; color:#000000; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Calcium" title="Calcium"><span style="display:block">Ca</span></a></span> </td> <td style="background:#e1e1e1;"> </td> <td title="Sc, Scandium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Scandium" title="Scandium"><span style="display:block">Sc</span></a></span> </td> <td title="Ti, Titanium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Titanium" title="Titanium"><span style="display:block">Ti</span></a></span> </td> <td title="V, Vanadium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Vanadium" title="Vanadium"><span style="display:block">V</span></a></span> </td> <td title="Cr, Chromium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Chromium" title="Chromium"><span style="display:block">Cr</span></a></span> </td> <td title="Mn, Manganese" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Manganese" title="Manganese"><span style="display:block">Mn</span></a></span> </td> <td title="Fe, Iron" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Iron" title="Iron"><span style="display:block">Fe</span></a></span> </td> <td title="Co, Cobalt" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Cobalt" title="Cobalt"><span style="display:block">Co</span></a></span> </td> <td title="Ni, Nickel" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Nickel" title="Nickel"><span style="display:block">Ni</span></a></span> </td> <td title="Cu, Copper" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Copper" title="Copper"><span style="display:block">Cu</span></a></span> </td> <td title="Zn, Zinc" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Zinc" title="Zinc"><span style="display:block">Zn</span></a></span> </td> <td title="Ga, Gallium" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Gallium" title="Gallium"><span style="display:block">Ga</span></a></span> </td> <td title="Ge, Germanium" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Germanium" title="Germanium"><span style="display:block">Ge</span></a></span> </td> <td title="As, Arsenic" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Arsenic" title="Arsenic"><span style="display:block">As</span></a></span> </td> <td title="Se, Selenium" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Selenium" title="Selenium"><span style="display:block">Se</span></a></span> </td> <td title="Br, Bromine" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Bromine" title="Bromine"><span style="display:block">Br</span></a></span> </td> <td title="Kr, Krypton" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Krypton" title="Krypton"><span style="display:block">Kr</span></a></span> </td></tr> <tr> <td style="text-align:right; padding-right:1em;"><a href="/wiki/Period_5_element" title="Period 5 element">Period 5</a> </td> <td title="Rb, Rubidium" style="text-align:center; color:#000000; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Rubidium" title="Rubidium"><span style="display:block">Rb</span></a></span> </td> <td title="Sr, Strontium" style="text-align:center; color:#000000; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Strontium" title="Strontium"><span style="display:block">Sr</span></a></span> </td> <td style="background:#e1e1e1;"> </td> <td title="Y, Yttrium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Yttrium" title="Yttrium"><span style="display:block">Y</span></a></span> </td> <td title="Zr, Zirconium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Zirconium" title="Zirconium"><span style="display:block">Zr</span></a></span> </td> <td title="Nb, Niobium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Niobium" title="Niobium"><span style="display:block">Nb</span></a></span> </td> <td title="Mo, Molybdenum" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Molybdenum" title="Molybdenum"><span style="display:block">Mo</span></a></span> </td> <td title="Tc, Technetium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Technetium" title="Technetium"><span style="display:block">Tc</span></a></span> </td> <td title="Ru, Ruthenium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Ruthenium" title="Ruthenium"><span style="display:block">Ru</span></a></span> </td> <td title="Rh, Rhodium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Rhodium" title="Rhodium"><span style="display:block">Rh</span></a></span> </td> <td title="Pd, Palladium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Palladium" title="Palladium"><span style="display:block">Pd</span></a></span> </td> <td title="Ag, Silver" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Silver" title="Silver"><span style="display:block">Ag</span></a></span> </td> <td title="Cd, Cadmium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Cadmium" title="Cadmium"><span style="display:block">Cd</span></a></span> </td> <td title="In, Indium" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Indium" title="Indium"><span style="display:block">In</span></a></span> </td> <td title="Sn, Tin" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Tin" title="Tin"><span style="display:block">Sn</span></a></span> </td> <td title="Sb, Antimony" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Antimony" title="Antimony"><span style="display:block">Sb</span></a></span> </td> <td title="Te, Tellurium" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Tellurium" title="Tellurium"><span style="display:block">Te</span></a></span> </td> <td title="I, Iodine" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Iodine" title="Iodine"><span style="display:block">I</span></a></span> </td> <td title="Xe, Xenon" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Xenon" title="Xenon"><span style="display:block">Xe</span></a></span> </td></tr> <tr> <td style="text-align:right; padding-right:1em;"><a href="/wiki/Period_6_element" title="Period 6 element">Period 6</a> </td> <td title="Cs, Caesium" style="text-align:center; color:#000000; background-color:#ff9999; border:none; min-width:4%;;"><span class="nowrap"><a href="/wiki/Caesium" title="Caesium"><span style="display:block">Cs</span></a></span> </td> <td title="Ba, Barium" style="text-align:center; color:#000000; background-color:#ff9999; border:none; min-width:4%;;"><span class="nowrap"><a href="/wiki/Barium" title="Barium"><span style="display:block">Ba</span></a></span> </td> <td style="font-size:95%; background:#9bff99; padding:0 1px; width:*;"><a href="/wiki/Lanthanide" title="Lanthanide">La–Yb</a> </td> <td title="Lu, Lutetium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; min-width:4%;;"><span class="nowrap"><a href="/wiki/Lutetium" title="Lutetium"><span style="display:block">Lu</span></a></span> </td> <td title="Hf, Hafnium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; min-width:4%;;"><span class="nowrap"><a href="/wiki/Hafnium" title="Hafnium"><span style="display:block">Hf</span></a></span> </td> <td title="Ta, Tantalum" style="text-align:center; color:#000000; background-color:#99ccff; border:none; min-width:4%;;"><span class="nowrap"><a href="/wiki/Tantalum" title="Tantalum"><span style="display:block">Ta</span></a></span> </td> <td title="W, Tungsten" style="text-align:center; color:#000000; background-color:#99ccff; border:none; min-width:4%;;"><span class="nowrap"><a href="/wiki/Tungsten" title="Tungsten"><span style="display:block">W</span></a></span> </td> <td title="Re, Rhenium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; min-width:4%;;"><span class="nowrap"><a href="/wiki/Rhenium" title="Rhenium"><span style="display:block">Re</span></a></span> </td> <td title="Os, Osmium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; min-width:4%;;"><span class="nowrap"><a href="/wiki/Osmium" title="Osmium"><span style="display:block">Os</span></a></span> </td> <td title="Ir, Iridium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; min-width:4%;;"><span class="nowrap"><a href="/wiki/Iridium" title="Iridium"><span style="display:block">Ir</span></a></span> </td> <td title="Pt, Platinum" style="text-align:center; color:#000000; background-color:#99ccff; border:none; min-width:4%;;"><span class="nowrap"><a href="/wiki/Platinum" title="Platinum"><span style="display:block">Pt</span></a></span> </td> <td title="Au, Gold" style="text-align:center; color:#000000; background-color:#99ccff; border:none; min-width:4%;;"><span class="nowrap"><a href="/wiki/Gold" title="Gold"><span style="display:block">Au</span></a></span> </td> <td title="Hg, Mercury" style="text-align:center; color:#000000; background-color:#99ccff; border:none; min-width:4%;;"><span class="nowrap"><a href="/wiki/Mercury_(element)" title="Mercury (element)"><span style="display:block">Hg</span></a></span> </td> <td title="Tl, Thallium" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; min-width:4%;;"><span class="nowrap"><a href="/wiki/Thallium" title="Thallium"><span style="display:block">Tl</span></a></span> </td> <td title="Pb, Lead" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; min-width:4%;;"><span class="nowrap"><a href="/wiki/Lead" title="Lead"><span style="display:block">Pb</span></a></span> </td> <td title="Bi, Bismuth" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; min-width:4%;;"><span class="nowrap"><a href="/wiki/Bismuth" title="Bismuth"><span style="display:block">Bi</span></a></span> </td> <td title="Po, Polonium" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; min-width:4%;;"><span class="nowrap"><a href="/wiki/Polonium" title="Polonium"><span style="display:block">Po</span></a></span> </td> <td title="At, Astatine" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; min-width:4%;;"><span class="nowrap"><a href="/wiki/Astatine" title="Astatine"><span style="display:block">At</span></a></span> </td> <td title="Rn, Radon" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; min-width:4%;;"><span class="nowrap"><a href="/wiki/Radon" title="Radon"><span style="display:block">Rn</span></a></span> </td></tr> <tr> <td style="text-align:right; padding-right:1em;"><a href="/wiki/Period_7_element" title="Period 7 element">Period 7</a> </td> <td title="Fr, Francium" style="text-align:center; color:#000000; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Francium" title="Francium"><span style="display:block">Fr</span></a></span> </td> <td title="Ra, Radium" style="text-align:center; color:#000000; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Radium" title="Radium"><span style="display:block">Ra</span></a></span> </td> <td style="font-size:95%; background:#9bff99; padding:0 1px;"><span class="nowrap"><a href="/wiki/Actinide" title="Actinide">Ac–No</a></span> </td> <td title="Lr, Lawrencium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Lawrencium" title="Lawrencium"><span style="display:block">Lr</span></a></span> </td> <td title="Rf, Rutherfordium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Rutherfordium" title="Rutherfordium"><span style="display:block">Rf</span></a></span> </td> <td title="Db, Dubnium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Dubnium" title="Dubnium"><span style="display:block">Db</span></a></span> </td> <td title="Sg, Seaborgium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Seaborgium" title="Seaborgium"><span style="display:block">Sg</span></a></span> </td> <td title="Bh, Bohrium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Bohrium" title="Bohrium"><span style="display:block">Bh</span></a></span> </td> <td title="Hs, Hassium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Hassium" title="Hassium"><span style="display:block">Hs</span></a></span> </td> <td title="Mt, Meitnerium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Meitnerium" title="Meitnerium"><span style="display:block">Mt</span></a></span> </td> <td title="Ds, Darmstadtium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Darmstadtium" title="Darmstadtium"><span style="display:block">Ds</span></a></span> </td> <td title="Rg, Roentgenium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Roentgenium" title="Roentgenium"><span style="display:block">Rg</span></a></span> </td> <td title="Cn, Copernicium" style="text-align:center; color:#000000; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Copernicium" title="Copernicium"><span style="display:block">Cn</span></a></span> </td> <td title="Nh, Nihonium" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Nihonium" title="Nihonium"><span style="display:block">Nh</span></a></span> </td> <td title="Fl, Flerovium" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Flerovium" title="Flerovium"><span style="display:block">Fl</span></a></span> </td> <td title="Mc, Moscovium" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Moscovium" title="Moscovium"><span style="display:block">Mc</span></a></span> </td> <td title="Lv, Livermorium" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Livermorium" title="Livermorium"><span style="display:block">Lv</span></a></span> </td> <td title="Ts, Tennessine" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Tennessine" title="Tennessine"><span style="display:block">Ts</span></a></span> </td> <td title="Og, Oganesson" style="text-align:center; color:#000000; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Oganesson" title="Oganesson"><span style="display:block">Og</span></a></span> </td></tr></tbody></table> <div style="text-align:left; background:#f0f0f0"><span class="anchor" id="Group_1b"></span><style data-mw-deduplicate="TemplateStyles:r1041539562">.mw-parser-output .citation{word-wrap:break-word}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}</style><span class="citation wikicite" id="endnote_group1"><sup>a</sup></span> Group 1 is composed of hydrogen (H) and the alkali metals. Elements of the group have one s-electron in the outer electron shell. Hydrogen is not considered to be an alkali metal as it is not a metal, though it is more analogous to them than any other group. This makes the group somewhat exceptional.<br /><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1041539562"><span class="citation wikicite" id="endnote_f-block_groups"><sup>b</sup></span> The 14 <a href="/wiki/F-block_groups" class="mw-redirect" title="F-block groups">f-block groups</a> (columns) do not have a group number.<br /><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1041539562"><span class="citation wikicite" id="endnote_ScYLu"><sup>c</sup></span> The correct composition of group 3 is scandium (Sc), yttrium (Y), lutetium (Lu), and lawrencium (Lr), as shown here: this is endorsed by 1988<sup id="cite_ref-Fluck_27-1" class="reference"><a href="#cite_note-Fluck-27"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> and 2021<sup id="cite_ref-2021IUPAC_28-0" class="reference"><a href="#cite_note-2021IUPAC-28"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> IUPAC reports on the question. General inorganic chemistry texts often put scandium (Sc), yttrium (Y), lanthanum (La), and actinium (Ac) in group 3, so that Ce–Lu and Th–Lr become the f-block between groups 3 and 4; this was based on incorrectly measured electron configurations from history,<sup id="cite_ref-Jensen1982_29-0" class="reference"><a href="#cite_note-Jensen1982-29"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> and <a href="/wiki/Lev_Landau" title="Lev Landau">Lev Landau</a> and <a href="/wiki/Evgeny_Lifshitz" title="Evgeny Lifshitz">Evgeny Lifshitz</a> already considered it incorrect in 1948.<sup id="cite_ref-Landau_30-0" class="reference"><a href="#cite_note-Landau-30"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> Arguments can still occasionally be encountered in the contemporary literature purporting to defend it, but most authors consider them logically inconsistent.<sup id="cite_ref-Jensen2015_31-0" class="reference"><a href="#cite_note-Jensen2015-31"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Scerri2009_32-0" class="reference"><a href="#cite_note-Scerri2009-32"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Chemey_33-0" class="reference"><a href="#cite_note-Chemey-33"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> Some sources follow a compromise that puts La–Lu and Ac–Lr as the f-block rows (despite that giving 15 f-block elements in each row, which contradicts quantum mechanics), leaving the heavier members of group 3 ambiguous.<sup id="cite_ref-2021IUPAC_28-1" class="reference"><a href="#cite_note-2021IUPAC-28"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> See also <a href="/wiki/Group_3_element#Composition" title="Group 3 element">Group 3 element#Composition</a>.<br /><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1041539562"><span class="citation wikicite" id="endnote_group0"><sup>d</sup></span> Group 18, the noble gases, were not discovered at the time of Mendeleev's original table. Later (1902), Mendeleev accepted the evidence for their existence, and they could be placed in a new "group 0", consistently and without breaking the periodic table principle.<br /><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1041539562"><span class="citation wikicite" id="endnote_IUPAC"><sup>r</sup></span> Group name as recommended by IUPAC.</div> </div></div> <div class="mw-heading mw-heading3"><h3 id="Presentation_forms">Presentation forms<span class="anchor" id="The_long-_or_32-column_table"></span></h3></div> <div style="border:1px solid grey; float:right; text-align:center; padding:0.2em; margin:0; font-size:90%;"> <div style="background-color:transparent; color:inherit; margin:0; padding:0; text-align:center; border:none;"> <table style="empty-cells:hidden; border:none; padding:0; border-spacing:1px; border-collapse:separate; margin:0;"> <tbody><tr> <td style="border:none;padding:0;"><a href="/wiki/Hydrogen" title="Hydrogen"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Hydrogen</span></a> </td> <td colspan="30" style="border:none;padding:0;"> </td> <td style="border:none;padding:0;"><a href="/wiki/Helium" title="Helium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Helium</span></a> </td></tr> <tr> <td style="border:none;padding:0;"><a href="/wiki/Lithium" title="Lithium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Lithium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Beryllium" title="Beryllium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Beryllium</span></a> </td> <td colspan="24" style="border:none;padding:0;"> </td> <td style="border:none;padding:0;"><a href="/wiki/Boron" title="Boron"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Boron</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Carbon" title="Carbon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Carbon</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Nitrogen" title="Nitrogen"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Nitrogen</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Oxygen" title="Oxygen"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Oxygen</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Fluorine" title="Fluorine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Fluorine</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Neon" title="Neon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Neon</span></a> </td></tr> <tr> <td style="border:none;padding:0;"><a href="/wiki/Sodium" title="Sodium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Sodium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Magnesium" title="Magnesium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Magnesium</span></a> </td> <td colspan="24" style="border:none;padding:0;"> </td> <td style="border:none;padding:0;"><a href="/wiki/Aluminium" title="Aluminium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Aluminium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Silicon" title="Silicon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Silicon</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Phosphorus" title="Phosphorus"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Phosphorus</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Sulfur" title="Sulfur"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Sulfur</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Chlorine" title="Chlorine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Chlorine</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Argon" title="Argon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Argon</span></a> </td></tr> <tr> <td style="border:none;padding:0;"><a href="/wiki/Potassium" title="Potassium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Potassium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Calcium" title="Calcium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Calcium</span></a> </td> <td colspan="14" style="border:none;padding:0;"> </td> <td style="border:none;padding:0;"><a href="/wiki/Scandium" title="Scandium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Scandium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Titanium" title="Titanium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Titanium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Vanadium" title="Vanadium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Vanadium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Chromium" title="Chromium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Chromium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Manganese" title="Manganese"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Manganese</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Iron" title="Iron"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Iron</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Cobalt" title="Cobalt"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Cobalt</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Nickel" title="Nickel"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Nickel</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Copper" title="Copper"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Copper</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Zinc" title="Zinc"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Zinc</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Gallium" title="Gallium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Gallium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Germanium" title="Germanium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Germanium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Arsenic" title="Arsenic"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Arsenic</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Selenium" title="Selenium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Selenium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Bromine" title="Bromine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Bromine</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Krypton" title="Krypton"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Krypton</span></a> </td></tr> <tr> <td style="border:none;padding:0;"><a href="/wiki/Rubidium" title="Rubidium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Rubidium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Strontium" title="Strontium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Strontium</span></a> </td> <td style="border:none;padding:0;; width:0;"> </td> <td colspan="13" style="border:none;padding:0;"> </td> <td style="border:none;padding:0;"><a href="/wiki/Yttrium" title="Yttrium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Yttrium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Zirconium" title="Zirconium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Zirconium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Niobium" title="Niobium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Niobium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Molybdenum" title="Molybdenum"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Molybdenum</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Technetium" title="Technetium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Technetium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Ruthenium" title="Ruthenium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Ruthenium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Rhodium" title="Rhodium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Rhodium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Palladium" title="Palladium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Palladium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Silver" title="Silver"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Silver</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Cadmium" title="Cadmium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Cadmium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Indium" title="Indium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Indium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Tin" title="Tin"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Tin</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Antimony" title="Antimony"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Antimony</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Tellurium" title="Tellurium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Tellurium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Iodine" title="Iodine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Iodine</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Xenon" title="Xenon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Xenon</span></a> </td></tr> <tr style="border:none;padding:0;"> <td style="border:none;padding:0;"><a href="/wiki/Caesium" title="Caesium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Caesium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Barium" title="Barium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Barium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Lanthanum" title="Lanthanum"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Lanthanum</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Cerium" title="Cerium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Cerium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Praseodymium" title="Praseodymium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Praseodymium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Neodymium" title="Neodymium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Neodymium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Promethium" title="Promethium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Promethium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Samarium" title="Samarium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Samarium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Europium" title="Europium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Europium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Gadolinium" title="Gadolinium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Gadolinium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Terbium" title="Terbium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Terbium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Dysprosium" title="Dysprosium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Dysprosium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Holmium" title="Holmium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Holmium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Erbium" title="Erbium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Erbium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Thulium" title="Thulium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Thulium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Ytterbium" title="Ytterbium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Ytterbium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Lutetium" title="Lutetium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Lutetium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Hafnium" title="Hafnium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Hafnium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Tantalum" title="Tantalum"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Tantalum</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Tungsten" title="Tungsten"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Tungsten</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Rhenium" title="Rhenium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Rhenium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Osmium" title="Osmium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Osmium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Iridium" title="Iridium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Iridium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Platinum" title="Platinum"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Platinum</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Gold" title="Gold"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Gold</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Mercury_(element)" title="Mercury (element)"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Mercury (element)</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Thallium" title="Thallium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Thallium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Lead" title="Lead"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Lead</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Bismuth" title="Bismuth"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Bismuth</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Polonium" title="Polonium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Polonium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Astatine" title="Astatine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Astatine</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Radon" title="Radon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Radon</span></a> </td></tr> <tr> <td style="border:none;padding:0;"><a href="/wiki/Francium" title="Francium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Francium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Radium" title="Radium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Radium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Actinium" title="Actinium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Actinium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Thorium" title="Thorium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Thorium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Protactinium" title="Protactinium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Protactinium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Uranium" title="Uranium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Uranium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Neptunium" title="Neptunium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Neptunium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Plutonium" title="Plutonium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Plutonium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Americium" title="Americium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Americium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Curium" title="Curium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Curium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Berkelium" title="Berkelium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Berkelium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Californium" title="Californium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Californium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Einsteinium" title="Einsteinium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Einsteinium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Fermium" title="Fermium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Fermium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Mendelevium" title="Mendelevium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Mendelevium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Nobelium" title="Nobelium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Nobelium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Lawrencium" title="Lawrencium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Lawrencium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Rutherfordium" title="Rutherfordium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Rutherfordium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Dubnium" title="Dubnium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Dubnium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Seaborgium" title="Seaborgium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Seaborgium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Bohrium" title="Bohrium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Bohrium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Hassium" title="Hassium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Hassium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Meitnerium" title="Meitnerium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Meitnerium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Darmstadtium" title="Darmstadtium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Darmstadtium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Roentgenium" title="Roentgenium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Roentgenium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Copernicium" title="Copernicium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Copernicium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Nihonium" title="Nihonium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Nihonium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Flerovium" title="Flerovium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Flerovium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Moscovium" title="Moscovium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Moscovium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Livermorium" title="Livermorium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Livermorium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Tennessine" title="Tennessine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Tennessine</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Oganesson" title="Oganesson"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Oganesson</span></a> </td></tr></tbody></table> </div> <p>32 columns </p> <table role="presentation" id="periodic-table-(micro,_18-column)" class="nogrid" cellpadding="0" cellspacing="1" style="overflow:hidden; background-color:transparent; text-align: center; empty-cells: show; border:none"> <tbody><tr> <td style="border:none"><a href="/wiki/Hydrogen" title="Hydrogen"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Hydrogen</span></a> </td> <td colspan="17" style="border:none"> </td> <td style="border:none"><a href="/wiki/Helium" title="Helium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Helium</span></a> </td></tr> <tr> <td style="border:none"><a href="/wiki/Lithium" title="Lithium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Lithium</span></a> </td> <td style="border:none"><a href="/wiki/Beryllium" title="Beryllium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Beryllium</span></a> </td> <td colspan="11" style="border:none"> </td> <td style="border:none"><a href="/wiki/Boron" title="Boron"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Boron</span></a> </td> <td style="border:none"><a href="/wiki/Carbon" title="Carbon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Carbon</span></a> </td> <td style="border:none"><a href="/wiki/Nitrogen" title="Nitrogen"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Nitrogen</span></a> </td> <td style="border:none"><a href="/wiki/Oxygen" title="Oxygen"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Oxygen</span></a> </td> <td style="border:none"><a href="/wiki/Fluorine" title="Fluorine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Fluorine</span></a> </td> <td style="border:none"><a href="/wiki/Neon" title="Neon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Neon</span></a> </td></tr> <tr> <td style="border:none"><a href="/wiki/Sodium" title="Sodium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Sodium</span></a> </td> <td style="border:none"><a href="/wiki/Magnesium" title="Magnesium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Magnesium</span></a> </td> <td colspan="11" style="border:none"> </td> <td style="border:none"><a href="/wiki/Aluminium" title="Aluminium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Aluminium</span></a> </td> <td style="border:none"><a href="/wiki/Silicon" title="Silicon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Silicon</span></a> </td> <td style="border:none"><a href="/wiki/Phosphorus" title="Phosphorus"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Phosphorus</span></a> </td> <td style="border:none"><a href="/wiki/Sulfur" title="Sulfur"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Sulfur</span></a> </td> <td style="border:none"><a href="/wiki/Chlorine" title="Chlorine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Chlorine</span></a> </td> <td style="border:none"><a href="/wiki/Argon" title="Argon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Argon</span></a> </td></tr> <tr> <td style="border:none"><a href="/wiki/Potassium" title="Potassium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Potassium</span></a> </td> <td style="border:none"><a href="/wiki/Calcium" title="Calcium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Calcium</span></a> </td> <td style="border:none"> </td> <td style="border:none"><a href="/wiki/Scandium" title="Scandium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Scandium</span></a> </td> <td style="border:none"><a href="/wiki/Titanium" title="Titanium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Titanium</span></a> </td> <td style="border:none"><a href="/wiki/Vanadium" title="Vanadium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Vanadium</span></a> </td> <td style="border:none"><a href="/wiki/Chromium" title="Chromium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Chromium</span></a> </td> <td style="border:none"><a href="/wiki/Manganese" title="Manganese"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Manganese</span></a> </td> <td style="border:none"><a href="/wiki/Iron" title="Iron"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Iron</span></a> </td> <td style="border:none"><a href="/wiki/Cobalt" title="Cobalt"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Cobalt</span></a> </td> <td style="border:none"><a href="/wiki/Nickel" title="Nickel"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Nickel</span></a> </td> <td style="border:none"><a href="/wiki/Copper" title="Copper"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Copper</span></a> </td> <td style="border:none"><a href="/wiki/Zinc" title="Zinc"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Zinc</span></a> </td> <td style="border:none"><a href="/wiki/Gallium" title="Gallium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Gallium</span></a> </td> <td style="border:none"><a href="/wiki/Germanium" title="Germanium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Germanium</span></a> </td> <td style="border:none"><a href="/wiki/Arsenic" title="Arsenic"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Arsenic</span></a> </td> <td style="border:none"><a href="/wiki/Selenium" title="Selenium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Selenium</span></a> </td> <td style="border:none"><a href="/wiki/Bromine" title="Bromine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Bromine</span></a> </td> <td style="border:none"><a href="/wiki/Krypton" title="Krypton"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Krypton</span></a> </td></tr> <tr> <td style="border:none"><a href="/wiki/Rubidium" title="Rubidium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Rubidium</span></a> </td> <td style="border:none"><a href="/wiki/Strontium" title="Strontium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Strontium</span></a> </td> <td style="border:none"> </td> <td style="border:none"><a href="/wiki/Yttrium" title="Yttrium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Yttrium</span></a> </td> <td style="border:none"><a href="/wiki/Zirconium" title="Zirconium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Zirconium</span></a> </td> <td style="border:none"><a href="/wiki/Niobium" title="Niobium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Niobium</span></a> </td> <td style="border:none"><a href="/wiki/Molybdenum" title="Molybdenum"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Molybdenum</span></a> </td> <td style="border:none"><a href="/wiki/Technetium" title="Technetium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Technetium</span></a> </td> <td style="border:none"><a href="/wiki/Ruthenium" title="Ruthenium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Ruthenium</span></a> </td> <td style="border:none"><a href="/wiki/Rhodium" title="Rhodium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Rhodium</span></a> </td> <td style="border:none"><a href="/wiki/Palladium" title="Palladium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Palladium</span></a> </td> <td style="border:none"><a href="/wiki/Silver" title="Silver"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Silver</span></a> </td> <td style="border:none"><a href="/wiki/Cadmium" title="Cadmium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Cadmium</span></a> </td> <td style="border:none"><a href="/wiki/Indium" title="Indium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Indium</span></a> </td> <td style="border:none"><a href="/wiki/Tin" title="Tin"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Tin</span></a> </td> <td style="border:none"><a href="/wiki/Antimony" title="Antimony"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Antimony</span></a> </td> <td style="border:none"><a href="/wiki/Tellurium" title="Tellurium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Tellurium</span></a> </td> <td style="border:none"><a href="/wiki/Iodine" title="Iodine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Iodine</span></a> </td> <td style="border:none"><a href="/wiki/Xenon" title="Xenon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Xenon</span></a> </td></tr> <tr style="border:none"> <td style="border:none"><a href="/wiki/Caesium" title="Caesium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Caesium</span></a> </td> <td style="border:none"><a href="/wiki/Barium" title="Barium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Barium</span></a> </td> <td style="border:none"><div style="float:left; margin:3px 2px; background:black; width:1px; height:1px;"></div> </td> <td style="border:none"><a href="/wiki/Lutetium" title="Lutetium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Lutetium</span></a> </td> <td style="border:none"><a href="/wiki/Hafnium" title="Hafnium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Hafnium</span></a> </td> <td style="border:none"><a href="/wiki/Tantalum" title="Tantalum"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Tantalum</span></a> </td> <td style="border:none"><a href="/wiki/Tungsten" title="Tungsten"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Tungsten</span></a> </td> <td style="border:none"><a href="/wiki/Rhenium" title="Rhenium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Rhenium</span></a> </td> <td style="border:none"><a href="/wiki/Osmium" title="Osmium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Osmium</span></a> </td> <td style="border:none"><a href="/wiki/Iridium" title="Iridium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Iridium</span></a> </td> <td style="border:none"><a href="/wiki/Platinum" title="Platinum"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Platinum</span></a> </td> <td style="border:none"><a href="/wiki/Gold" title="Gold"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Gold</span></a> </td> <td style="border:none"><a href="/wiki/Mercury_(element)" title="Mercury (element)"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Mercury (element)</span></a> </td> <td style="border:none"><a href="/wiki/Thallium" title="Thallium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Thallium</span></a> </td> <td style="border:none"><a href="/wiki/Lead" title="Lead"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Lead</span></a> </td> <td style="border:none"><a href="/wiki/Bismuth" title="Bismuth"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Bismuth</span></a> </td> <td style="border:none"><a href="/wiki/Polonium" title="Polonium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Polonium</span></a> </td> <td style="border:none"><a href="/wiki/Astatine" title="Astatine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Astatine</span></a> </td> <td style="border:none"><a href="/wiki/Radon" title="Radon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Radon</span></a> </td></tr> <tr> <td style="border:none"><a href="/wiki/Francium" title="Francium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Francium</span></a> </td> <td style="border:none"><a href="/wiki/Radium" title="Radium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Radium</span></a> </td> <td style="border:none"><div style="float:left; margin:1px 2px; background:black; width:1px; height:4px;"></div> </td> <td style="border:none"><a href="/wiki/Lawrencium" title="Lawrencium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Lawrencium</span></a> </td> <td style="border:none"><a href="/wiki/Rutherfordium" title="Rutherfordium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Rutherfordium</span></a> </td> <td style="border:none"><a href="/wiki/Dubnium" title="Dubnium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Dubnium</span></a> </td> <td style="border:none"><a href="/wiki/Seaborgium" title="Seaborgium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Seaborgium</span></a> </td> <td style="border:none"><a href="/wiki/Bohrium" title="Bohrium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Bohrium</span></a> </td> <td style="border:none"><a href="/wiki/Hassium" title="Hassium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Hassium</span></a> </td> <td style="border:none"><a href="/wiki/Meitnerium" title="Meitnerium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Meitnerium</span></a> </td> <td style="border:none"><a href="/wiki/Darmstadtium" title="Darmstadtium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Darmstadtium</span></a> </td> <td style="border:none"><a href="/wiki/Roentgenium" title="Roentgenium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Roentgenium</span></a> </td> <td style="border:none"><a href="/wiki/Copernicium" title="Copernicium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Copernicium</span></a> </td> <td style="border:none"><a href="/wiki/Nihonium" title="Nihonium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Nihonium</span></a> </td> <td style="border:none"><a href="/wiki/Flerovium" title="Flerovium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Flerovium</span></a> </td> <td style="border:none"><a href="/wiki/Moscovium" title="Moscovium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Moscovium</span></a> </td> <td style="border:none"><a href="/wiki/Livermorium" title="Livermorium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Livermorium</span></a> </td> <td style="border:none"><a href="/wiki/Tennessine" title="Tennessine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Tennessine</span></a> </td> <td style="border:none"><a href="/wiki/Oganesson" title="Oganesson"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Oganesson</span></a> </td></tr> <tr> <td style="line-height:4px">​ </td></tr> <tr> <td colspan="2"> </td> <td style="border:none"><div style="float:left; margin:3px 2px; background:black; width:1px; height:1px;"></div> </td> <td style="border:none"><a href="/wiki/Lanthanum" title="Lanthanum"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Lanthanum</span></a> </td> <td style="border:none"><a href="/wiki/Cerium" title="Cerium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Cerium</span></a> </td> <td style="border:none"><a href="/wiki/Praseodymium" title="Praseodymium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Praseodymium</span></a> </td> <td style="border:none"><a href="/wiki/Neodymium" title="Neodymium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Neodymium</span></a> </td> <td style="border:none"><a href="/wiki/Promethium" title="Promethium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Promethium</span></a> </td> <td style="border:none"><a href="/wiki/Samarium" title="Samarium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Samarium</span></a> </td> <td style="border:none"><a href="/wiki/Europium" title="Europium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Europium</span></a> </td> <td style="border:none"><a href="/wiki/Gadolinium" title="Gadolinium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Gadolinium</span></a> </td> <td style="border:none"><a href="/wiki/Terbium" title="Terbium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Terbium</span></a> </td> <td style="border:none"><a href="/wiki/Dysprosium" title="Dysprosium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Dysprosium</span></a> </td> <td style="border:none"><a href="/wiki/Holmium" title="Holmium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Holmium</span></a> </td> <td style="border:none"><a href="/wiki/Erbium" title="Erbium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Erbium</span></a> </td> <td style="border:none"><a href="/wiki/Thulium" title="Thulium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Thulium</span></a> </td> <td style="border:none"><a href="/wiki/Ytterbium" title="Ytterbium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Ytterbium</span></a> </td></tr> <tr> <td colspan="2"> </td> <td style="border:none"><div style="float:left; margin:1px 2px; background:black; width:1px; height:4px;"></div> </td> <td style="border:none"><a href="/wiki/Actinium" title="Actinium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Actinium</span></a> </td> <td style="border:none"><a href="/wiki/Thorium" title="Thorium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Thorium</span></a> </td> <td style="border:none"><a href="/wiki/Protactinium" title="Protactinium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Protactinium</span></a> </td> <td style="border:none"><a href="/wiki/Uranium" title="Uranium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Uranium</span></a> </td> <td style="border:none"><a href="/wiki/Neptunium" title="Neptunium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Neptunium</span></a> </td> <td style="border:none"><a href="/wiki/Plutonium" title="Plutonium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Plutonium</span></a> </td> <td style="border:none"><a href="/wiki/Americium" title="Americium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Americium</span></a> </td> <td style="border:none"><a href="/wiki/Curium" title="Curium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Curium</span></a> </td> <td style="border:none"><a href="/wiki/Berkelium" title="Berkelium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Berkelium</span></a> </td> <td style="border:none"><a href="/wiki/Californium" title="Californium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Californium</span></a> </td> <td style="border:none"><a href="/wiki/Einsteinium" title="Einsteinium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Einsteinium</span></a> </td> <td style="border:none"><a href="/wiki/Fermium" title="Fermium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Fermium</span></a> </td> <td style="border:none"><a href="/wiki/Mendelevium" title="Mendelevium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Mendelevium</span></a> </td> <td style="border:none"><a href="/wiki/Nobelium" title="Nobelium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Nobelium</span></a> </td></tr></tbody></table> <p>18 columns </p> </div> <p>For reasons of space,<sup id="cite_ref-Petrucci331_34-0" class="reference"><a href="#cite_note-Petrucci331-34"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-35" class="reference"><a href="#cite_note-35"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup> the periodic table is commonly presented with the f-block elements cut out and positioned as a distinct part below the main body.<sup id="cite_ref-cartoon_36-0" class="reference"><a href="#cite_note-cartoon-36"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Petrucci331_34-1" class="reference"><a href="#cite_note-Petrucci331-34"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Fluck_27-2" class="reference"><a href="#cite_note-Fluck-27"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> This reduces the number of element columns from 32 to 18.<sup id="cite_ref-Petrucci331_34-2" class="reference"><a href="#cite_note-Petrucci331-34"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> </p><p>Both forms represent the same periodic table.<sup id="cite_ref-IUPAC-redbook_7-3" class="reference"><a href="#cite_note-IUPAC-redbook-7"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> The form with the f-block included in the main body is sometimes called the 32-column<sup id="cite_ref-IUPAC-redbook_7-4" class="reference"><a href="#cite_note-IUPAC-redbook-7"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> or long form;<sup id="cite_ref-Thyssen_37-0" class="reference"><a href="#cite_note-Thyssen-37"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> the form with the f-block cut out the 18-column<sup id="cite_ref-IUPAC-redbook_7-5" class="reference"><a href="#cite_note-IUPAC-redbook-7"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> or medium-long form.<sup id="cite_ref-Thyssen_37-1" class="reference"><a href="#cite_note-Thyssen-37"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> The 32-column form has the advantage of showing all elements in their correct sequence, but it has the disadvantage of requiring more space.<sup id="cite_ref-38" class="reference"><a href="#cite_note-38"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup> The form chosen is an editorial choice, and does not imply any change of scientific claim or statement. For example, when discussing <a href="/wiki/Group_3_element#Composition" title="Group 3 element">the composition of group 3</a>, the options can be shown equally (unprejudiced) in both forms.<sup id="cite_ref-2015IUPAC_39-0" class="reference"><a href="#cite_note-2015IUPAC-39"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup> </p><p>Periodic tables usually at least show the elements' symbols; many also provide supplementary information about the elements, either via colour-coding or as data in the cells. The above table shows the names and atomic numbers of the elements, and also their blocks, natural occurrences and <a href="/wiki/Standard_atomic_weight" title="Standard atomic weight">standard atomic weights</a>. For the short-lived elements without standard atomic weights, the mass number of the most stable known isotope is used instead. Other tables may include properties such as state of matter, melting and boiling points, densities, as well as provide different classifications of the elements.<sup id="cite_ref-40" class="reference"><a href="#cite_note-40"><span class="cite-bracket">[</span>e<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Electron_configurations">Electron configurations</h3></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Electron_configuration" title="Electron configuration">Electron configuration</a></div> <p>The periodic table is a graphic description of the periodic law,<sup id="cite_ref-Scerri17_41-0" class="reference"><a href="#cite_note-Scerri17-41"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup> which states that the properties and atomic structures of the chemical elements are a <a href="/wiki/Periodic_function" title="Periodic function">periodic function</a> of their <a href="/wiki/Atomic_number" title="Atomic number">atomic number</a>.<sup id="cite_ref-42" class="reference"><a href="#cite_note-42"><span class="cite-bracket">[</span>37<span class="cite-bracket">]</span></a></sup> Elements are placed in the periodic table according to their <a href="/wiki/Electron_configuration" title="Electron configuration">electron configurations</a>,<sup id="cite_ref-Jensen2009_43-0" class="reference"><a href="#cite_note-Jensen2009-43"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup> the periodic recurrences of which explain the <a href="/wiki/Periodic_trends" title="Periodic trends">trends</a> in properties across the periodic table.<sup id="cite_ref-FIII19_44-0" class="reference"><a href="#cite_note-FIII19-44"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup> </p><p>An electron can be thought of as inhabiting an <a href="/wiki/Atomic_orbital" title="Atomic orbital">atomic orbital</a>, which characterizes the probability it can be found in any particular region around the atom. Their energies are <a href="/wiki/Quantization_(physics)" title="Quantization (physics)">quantised</a>, which is to say that they can only take discrete values. Furthermore, electrons obey the <a href="/wiki/Pauli_exclusion_principle" title="Pauli exclusion principle">Pauli exclusion principle</a>: different electrons must always be in different states. This allows classification of the possible states an electron can take in various energy levels known as shells, divided into individual subshells, which each contain one or more orbitals. Each orbital can contain up to two electrons: they are distinguished by a quantity known as <a href="/wiki/Spin_(physics)" title="Spin (physics)">spin</a>, conventionally labelled "up" or "down".<sup id="cite_ref-45" class="reference"><a href="#cite_note-45"><span class="cite-bracket">[</span>40<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-47" class="reference"><a href="#cite_note-47"><span class="cite-bracket">[</span>f<span class="cite-bracket">]</span></a></sup> In a cold atom (one in its ground state), electrons arrange themselves in such a way that the total energy they have is minimized by occupying the lowest-energy orbitals available.<sup id="cite_ref-48" class="reference"><a href="#cite_note-48"><span class="cite-bracket">[</span>42<span class="cite-bracket">]</span></a></sup> Only the outermost electrons (so-called <a href="/wiki/Valence_electron" title="Valence electron">valence electrons</a>) have enough energy to break free of the nucleus and participate in chemical reactions with other atoms. The others are called <a href="/wiki/Core_electron" title="Core electron">core electrons</a>.<sup id="cite_ref-49" class="reference"><a href="#cite_note-49"><span class="cite-bracket">[</span>43<span class="cite-bracket">]</span></a></sup> </p> <table class="wikitable" style="float:right; margin:0.5em; text-align:center;"> <tbody><tr> <th style="text-align:right;">ℓ = </th> <th>0 </th> <th>1 </th> <th>2 </th> <th>3 </th> <th>4 </th> <th>5 </th> <th>6 </th> <th rowspan="2">Shell capacity (2<i>n</i><sup>2</sup>)<sup id="cite_ref-50" class="reference"><a href="#cite_note-50"><span class="cite-bracket">[</span>44<span class="cite-bracket">]</span></a></sup> </th></tr> <tr> <th style="text-align:right;">Orbital </th> <th>s </th> <th>p </th> <th>d </th> <th>f </th> <th>g </th> <th>h </th> <th>i </th></tr> <tr> <th><i>n</i> = 1 </th> <td bgcolor="#ff9999">1s </td> <td colspan="6"> </td> <td>2 </td></tr> <tr> <th><i>n</i> = 2 </th> <td bgcolor="#ff9999">2s </td> <td bgcolor="#fdff8c">2p </td> <td colspan="5"> </td> <td>8 </td></tr> <tr> <th><i>n</i> = 3 </th> <td bgcolor="#ff9999">3s </td> <td bgcolor="#fdff8c">3p </td> <td bgcolor="#99ccff">3d </td> <td colspan="4"> </td> <td>18 </td></tr> <tr> <th><i>n</i> = 4 </th> <td bgcolor="#ff9999">4s </td> <td bgcolor="#fdff8c">4p </td> <td bgcolor="#99ccff">4d </td> <td bgcolor="#9bff99">4f </td> <td colspan="3"> </td> <td>32 </td></tr> <tr> <th><i>n</i> = 5 </th> <td bgcolor="#ff9999">5s </td> <td bgcolor="#fdff8c">5p </td> <td bgcolor="#99ccff">5d </td> <td bgcolor="#9bff99">5f </td> <td bgcolor="#fd99ff">5g </td> <td colspan="2"> </td> <td>50 </td></tr> <tr> <th><i>n</i> = 6 </th> <td bgcolor="#ff9999">6s </td> <td bgcolor="#fdff8c">6p </td> <td bgcolor="#99ccff">6d </td> <td bgcolor="#9bff99">6f </td> <td bgcolor="#fd99ff">6g </td> <td bgcolor="#7ed9d9">6h </td> <td> </td> <td>72 </td></tr> <tr> <th><i>n</i> = 7 </th> <td bgcolor="#ff9999">7s </td> <td bgcolor="#fdff8c">7p </td> <td bgcolor="#99ccff">7d </td> <td bgcolor="#9bff99">7f </td> <td bgcolor="#fd99ff">7g </td> <td bgcolor="#7ed9d9">7h </td> <td bgcolor="#e0c880">7i </td> <td>98 </td></tr> <tr> <th>Subshell capacity (4ℓ+2) </th> <td>2 </td> <td>6 </td> <td>10 </td> <td>14 </td> <td>18 </td> <td>22 </td> <td>26 </td> <td> </td></tr></tbody></table> <p>Elements are known with up to the first seven shells occupied. The first shell contains only one orbital, a spherical s orbital. As it is in the first shell, this is called the 1s orbital. This can hold up to two electrons. The second shell similarly contains a 2s orbital, and it also contains three dumbbell-shaped 2p orbitals, and can thus fill up to eight electrons (2×1 + 2×3 = 8). The third shell contains one 3s orbital, three 3p orbitals, and five 3d orbitals, and thus has a capacity of 2×1 + 2×3 + 2×5 = 18. The fourth shell contains one 4s orbital, three 4p orbitals, five 4d orbitals, and seven 4f orbitals, thus leading to a capacity of 2×1 + 2×3 + 2×5 + 2×7 = 32.<sup id="cite_ref-Petrucci331_34-3" class="reference"><a href="#cite_note-Petrucci331-34"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> Higher shells contain more types of orbitals that continue the pattern, but such types of orbitals are not filled in the ground states of known elements.<sup id="cite_ref-Goudsmit_51-0" class="reference"><a href="#cite_note-Goudsmit-51"><span class="cite-bracket">[</span>45<span class="cite-bracket">]</span></a></sup> The subshell types are characterized by the <a href="/wiki/Quantum_number" title="Quantum number">quantum numbers</a>. Four numbers describe an orbital in an atom completely: the <a href="/wiki/Principal_quantum_number" title="Principal quantum number">principal quantum number</a> <i>n</i>, the <a href="/wiki/Azimuthal_quantum_number" title="Azimuthal quantum number">azimuthal quantum number</a> ℓ (the orbital type), the <a href="/wiki/Magnetic_quantum_number" title="Magnetic quantum number">orbital magnetic quantum number</a> <i>m</i><sub>ℓ</sub>, and the <a href="/wiki/Spin_quantum_number" title="Spin quantum number">spin magnetic quantum number</a> <i>m<sub>s</sub></i>.<sup id="cite_ref-FIII19_44-1" class="reference"><a href="#cite_note-FIII19-44"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading4"><h4 id="Order_of_subshell_filling">Order of subshell filling</h4></div> <figure class="mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Aufbau_Principle-en.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/2/2e/Aufbau_Principle-en.svg/192px-Aufbau_Principle-en.svg.png" decoding="async" width="192" height="193" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/2e/Aufbau_Principle-en.svg/288px-Aufbau_Principle-en.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/2e/Aufbau_Principle-en.svg/384px-Aufbau_Principle-en.svg.png 2x" data-file-width="737" data-file-height="741" /></a><figcaption>Idealized order of subshell filling according to the <a href="/wiki/Madelung_rule" class="mw-redirect" title="Madelung rule">Madelung rule</a> </figcaption></figure> <p>The sequence in which the subshells are filled is given in most cases by the <a href="/wiki/Aufbau_principle" title="Aufbau principle">Aufbau principle</a>, also known as the Madelung or Klechkovsky rule (after <a href="/wiki/Erwin_Madelung" title="Erwin Madelung">Erwin Madelung</a> and <a href="/wiki/Vsevolod_Klechkovsky" title="Vsevolod Klechkovsky">Vsevolod Klechkovsky</a> respectively). This rule was first observed empirically by Madelung, and Klechkovsky and later authors gave it theoretical justification.<sup id="cite_ref-Jolly_52-0" class="reference"><a href="#cite_note-Jolly-52"><span class="cite-bracket">[</span>46<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Ostrovsky_53-0" class="reference"><a href="#cite_note-Ostrovsky-53"><span class="cite-bracket">[</span>47<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Ostrovsky1981_54-0" class="reference"><a href="#cite_note-Ostrovsky1981-54"><span class="cite-bracket">[</span>48<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Wong_55-0" class="reference"><a href="#cite_note-Wong-55"><span class="cite-bracket">[</span>49<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-lowdin_56-0" class="reference"><a href="#cite_note-lowdin-56"><span class="cite-bracket">[</span>g<span class="cite-bracket">]</span></a></sup> The shells overlap in energies, and the Madelung rule specifies the sequence of filling according to:<sup id="cite_ref-Ostrovsky_53-1" class="reference"><a href="#cite_note-Ostrovsky-53"><span class="cite-bracket">[</span>47<span class="cite-bracket">]</span></a></sup> </p> <dl><dd>1s ≪ 2s < 2p ≪ 3s < 3p ≪ 4s < 3d < 4p ≪ 5s < 4d < 5p ≪ 6s < 4f < 5d < 6p ≪ 7s < 5f < 6d < 7p ≪ ...</dd></dl> <p>Here the sign ≪ means "much less than" as opposed to < meaning just "less than".<sup id="cite_ref-Ostrovsky_53-2" class="reference"><a href="#cite_note-Ostrovsky-53"><span class="cite-bracket">[</span>47<span class="cite-bracket">]</span></a></sup> Phrased differently, electrons enter orbitals in order of increasing <i>n</i> + ℓ, and if two orbitals are available with the same value of <i>n</i> + ℓ, the one with lower <i>n</i> is occupied first.<sup id="cite_ref-Goudsmit_51-1" class="reference"><a href="#cite_note-Goudsmit-51"><span class="cite-bracket">[</span>45<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Wong_55-1" class="reference"><a href="#cite_note-Wong-55"><span class="cite-bracket">[</span>49<span class="cite-bracket">]</span></a></sup> In general, orbitals with the same value of <i>n</i> + ℓ are similar in energy, but in the case of the s-orbitals (with ℓ = 0), quantum effects raise their energy to approach that of the next <i>n</i> + ℓ group. Hence the periodic table is usually drawn to begin each row (often called a period) with the filling of a new s-orbital, which corresponds to the beginning of a new shell.<sup id="cite_ref-Ostrovsky_53-3" class="reference"><a href="#cite_note-Ostrovsky-53"><span class="cite-bracket">[</span>47<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Ostrovsky1981_54-1" class="reference"><a href="#cite_note-Ostrovsky1981-54"><span class="cite-bracket">[</span>48<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Petrucci331_34-4" class="reference"><a href="#cite_note-Petrucci331-34"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> Thus, with the exception of the first row, each period length appears twice:<sup id="cite_ref-Ostrovsky_53-4" class="reference"><a href="#cite_note-Ostrovsky-53"><span class="cite-bracket">[</span>47<span class="cite-bracket">]</span></a></sup> </p> <dl><dd>2, 8, 8, 18, 18, 32, 32, ...</dd></dl> <p>The overlaps get quite close at the point where the d-orbitals enter the picture,<sup id="cite_ref-Petrucci328_57-0" class="reference"><a href="#cite_note-Petrucci328-57"><span class="cite-bracket">[</span>50<span class="cite-bracket">]</span></a></sup> and the order can shift slightly with atomic number<sup id="cite_ref-Cao_58-0" class="reference"><a href="#cite_note-Cao-58"><span class="cite-bracket">[</span>51<span class="cite-bracket">]</span></a></sup> and atomic charge.<sup id="cite_ref-Jorgensen_59-0" class="reference"><a href="#cite_note-Jorgensen-59"><span class="cite-bracket">[</span>52<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-65" class="reference"><a href="#cite_note-65"><span class="cite-bracket">[</span>h<span class="cite-bracket">]</span></a></sup> </p><p>Starting from the simplest atom, this lets us build up the periodic table one at a time in order of atomic number, by considering the cases of single atoms. In <a href="/wiki/Hydrogen" title="Hydrogen">hydrogen</a>, there is only one electron, which must go in the lowest-energy orbital 1s. This <a href="/wiki/Electron_configuration" title="Electron configuration">electron configuration</a> is written 1s<sup>1</sup>, where the superscript indicates the number of electrons in the subshell. <a href="/wiki/Helium" title="Helium">Helium</a> adds a second electron, which also goes into 1s, completely filling the first shell and giving the configuration 1s<sup>2</sup>.<sup id="cite_ref-FIII19_44-2" class="reference"><a href="#cite_note-FIII19-44"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-jensenlaw_66-0" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-68" class="reference"><a href="#cite_note-68"><span class="cite-bracket">[</span>i<span class="cite-bracket">]</span></a></sup> </p><p>Starting from the third element, <a href="/wiki/Lithium" title="Lithium">lithium</a>, the first shell is full, so its third electron occupies a 2s orbital, giving a 1s<sup>2</sup> 2s<sup>1</sup> configuration. The 2s electron is lithium's only valence electron, as the 1s subshell is now too tightly bound to the nucleus to participate in chemical bonding to other atoms: such a shell is called a "<a href="/wiki/Core_electron" title="Core electron">core shell</a>". The 1s subshell is a core shell for all elements from lithium onward. The 2s subshell is completed by the next element <a href="/wiki/Beryllium" title="Beryllium">beryllium</a> (1s<sup>2</sup> 2s<sup>2</sup>). The following elements then proceed to fill the 2p subshell. <a href="/wiki/Boron" title="Boron">Boron</a> (1s<sup>2</sup> 2s<sup>2</sup> 2p<sup>1</sup>) puts its new electron in a 2p orbital; <a href="/wiki/Carbon" title="Carbon">carbon</a> (1s<sup>2</sup> 2s<sup>2</sup> 2p<sup>2</sup>) fills a second 2p orbital; and with <a href="/wiki/Nitrogen" title="Nitrogen">nitrogen</a> (1s<sup>2</sup> 2s<sup>2</sup> 2p<sup>3</sup>) all three 2p orbitals become singly occupied. This is consistent with <a href="/wiki/Hund%27s_rule" class="mw-redirect" title="Hund's rule">Hund's rule</a>, which states that atoms usually prefer to singly occupy each orbital of the same type before filling them with the second electron. <a href="/wiki/Oxygen" title="Oxygen">Oxygen</a> (1s<sup>2</sup> 2s<sup>2</sup> 2p<sup>4</sup>), <a href="/wiki/Fluorine" title="Fluorine">fluorine</a> (1s<sup>2</sup> 2s<sup>2</sup> 2p<sup>5</sup>), and <a href="/wiki/Neon" title="Neon">neon</a> (1s<sup>2</sup> 2s<sup>2</sup> 2p<sup>6</sup>) then complete the already singly filled 2p orbitals; the last of these fills the second shell completely.<sup id="cite_ref-FIII19_44-3" class="reference"><a href="#cite_note-FIII19-44"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-jensenlaw_66-1" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> </p><p>Starting from element 11, <a href="/wiki/Sodium" title="Sodium">sodium</a>, the second shell is full, making the second shell a core shell for this and all heavier elements. The eleventh electron begins the filling of the third shell by occupying a 3s orbital, giving a configuration of 1s<sup>2</sup> 2s<sup>2</sup> 2p<sup>6</sup> 3s<sup>1</sup> for sodium. This configuration is abbreviated [Ne] 3s<sup>1</sup>, where [Ne] represents neon's configuration. <a href="/wiki/Magnesium" title="Magnesium">Magnesium</a> ([Ne] 3s<sup>2</sup>) finishes this 3s orbital, and the following six elements <a href="/wiki/Aluminium" title="Aluminium">aluminium</a>, <a href="/wiki/Silicon" title="Silicon">silicon</a>, <a href="/wiki/Phosphorus" title="Phosphorus">phosphorus</a>, <a href="/wiki/Sulfur" title="Sulfur">sulfur</a>, <a href="/wiki/Chlorine" title="Chlorine">chlorine</a>, and <a href="/wiki/Argon" title="Argon">argon</a> fill the three 3p orbitals ([Ne] 3s<sup>2</sup> 3p<sup>1</sup> through [Ne] 3s<sup>2</sup> 3p<sup>6</sup>).<sup id="cite_ref-FIII19_44-4" class="reference"><a href="#cite_note-FIII19-44"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-jensenlaw_66-2" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> This creates an analogous series in which the outer shell structures of sodium through argon are analogous to those of lithium through neon, and is the basis for the periodicity of chemical properties that the periodic table illustrates:<sup id="cite_ref-FIII19_44-5" class="reference"><a href="#cite_note-FIII19-44"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup> at regular but changing intervals of atomic numbers, the properties of the chemical elements approximately repeat.<sup id="cite_ref-Scerri17_41-1" class="reference"><a href="#cite_note-Scerri17-41"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup> </p><p>The first eighteen elements can thus be arranged as the start of a periodic table. Elements in the same column have the same number of valence electrons and have analogous valence electron configurations: these columns are called groups. The single exception is helium, which has two valence electrons like beryllium and magnesium, but is typically placed in the column of neon and argon to emphasise that its outer shell is full. (Some contemporary authors question even this single exception, preferring to consistently follow the valence configurations and place helium over beryllium.) There are eight columns in this periodic table fragment, corresponding to at most eight outer-shell electrons.<sup id="cite_ref-cartoon_36-1" class="reference"><a href="#cite_note-cartoon-36"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> A period begins when a new shell starts filling.<sup id="cite_ref-Petrucci331_34-5" class="reference"><a href="#cite_note-Petrucci331-34"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> Finally, the colouring illustrates the <a href="/wiki/Block_(periodic_table)" title="Block (periodic table)">blocks</a>: the elements in the s-block (coloured red) are filling s-orbitals, while those in the p-block (coloured yellow) are filling p-orbitals.<sup id="cite_ref-Petrucci331_34-6" class="reference"><a href="#cite_note-Petrucci331-34"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> </p> <table class="wikitable" style="margin:auto;"> <tbody><tr> <td bgcolor="#ff9999">1<br /><a href="/wiki/Hydrogen" title="Hydrogen">H</a> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td bgcolor="#ff9999">2<br /><a href="/wiki/Helium" title="Helium">He</a> </td> <td>2×1 = <b>2</b> elements<br /><span style="background:#ff9999; display:inline-block;">1s</span> <span style="display:inline-block;"><span style="visibility:hidden;color:transparent;">0p</span></span> </td></tr> <tr> <td bgcolor="#ff9999">3<br /><a href="/wiki/Lithium" title="Lithium">Li</a> </td> <td bgcolor="#ff9999">4<br /><a href="/wiki/Beryllium" title="Beryllium">Be</a> </td> <td bgcolor="#fdff8c">5<br /><a href="/wiki/Boron" title="Boron">B</a> </td> <td bgcolor="#fdff8c">6<br /><a href="/wiki/Carbon" title="Carbon">C</a> </td> <td bgcolor="#fdff8c">7<br /><a href="/wiki/Nitrogen" title="Nitrogen">N</a> </td> <td bgcolor="#fdff8c">8<br /><a href="/wiki/Oxygen" title="Oxygen">O</a> </td> <td bgcolor="#fdff8c">9<br /><a href="/wiki/Fluorine" title="Fluorine">F</a> </td> <td bgcolor="#fdff8c">10<br /><a href="/wiki/Neon" title="Neon">Ne</a> </td> <td><span class="nowrap">2×(1+3) = <b>8</b> elements</span><br /><span style="background:#ff9999; display:inline-block;">2s</span> <span style="background:#fdff8c; display:inline-block;">2p</span> </td></tr> <tr> <td bgcolor="#ff9999">11<br /><a href="/wiki/Sodium" title="Sodium">Na</a> </td> <td bgcolor="#ff9999">12<br /><a href="/wiki/Magnesium" title="Magnesium">Mg</a> </td> <td bgcolor="#fdff8c">13<br /><a href="/wiki/Aluminium" title="Aluminium">Al</a> </td> <td bgcolor="#fdff8c">14<br /><a href="/wiki/Silicon" title="Silicon">Si</a> </td> <td bgcolor="#fdff8c">15<br /><a href="/wiki/Phosphorus" title="Phosphorus">P</a> </td> <td bgcolor="#fdff8c">16<br /><a href="/wiki/Sulfur" title="Sulfur">S</a> </td> <td bgcolor="#fdff8c">17<br /><a href="/wiki/Chlorine" title="Chlorine">Cl</a> </td> <td bgcolor="#fdff8c">18<br /><a href="/wiki/Argon" title="Argon">Ar</a> </td> <td>2×(1+3) = <b>8</b> elements<br /><span style="background:#ff9999; display:inline-block;">3s</span> <span style="background:#fdff8c; display:inline-block;">3p</span> </td></tr></tbody></table> <p>Starting the next row, for <a href="/wiki/Potassium" title="Potassium">potassium</a> and <a href="/wiki/Calcium" title="Calcium">calcium</a> the 4s subshell is the lowest in energy, and therefore they fill it.<sup id="cite_ref-FIII19_44-6" class="reference"><a href="#cite_note-FIII19-44"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-jensenlaw_66-3" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> Potassium adds one electron to the 4s shell ([Ar] 4s<sup>1</sup>), and calcium then completes it ([Ar] 4s<sup>2</sup>). However, starting from <a href="/wiki/Scandium" title="Scandium">scandium</a> ([Ar] 3d<sup>1</sup> 4s<sup>2</sup>) the 3d subshell becomes the next highest in energy. The 4s and 3d subshells have approximately the same energy and they compete for filling the electrons, and so the occupation is not quite consistently filling the 3d orbitals one at a time. The precise energy ordering of 3d and 4s changes along the row, and also changes depending on how many electrons are removed from the atom. For example, due to the repulsion between the 3d electrons and the 4s ones, at <a href="/wiki/Chromium" title="Chromium">chromium</a> the 4s energy level becomes slightly higher than 3d, and so it becomes more profitable for a chromium atom to have a [Ar] 3d<sup>5</sup> 4s<sup>1</sup> configuration than an [Ar] 3d<sup>4</sup> 4s<sup>2</sup> one. A similar anomaly occurs at <a href="/wiki/Copper" title="Copper">copper</a>, whose atom has a [Ar] 3d<sup>10</sup> 4s<sup>1</sup> configuration rather than the expected [Ar] 3d<sup>9</sup> 4s<sup>2</sup>.<sup id="cite_ref-FIII19_44-7" class="reference"><a href="#cite_note-FIII19-44"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup> These are violations of the Madelung rule. Such anomalies, however, do not have any chemical significance:<sup id="cite_ref-Jorgensen_59-3" class="reference"><a href="#cite_note-Jorgensen-59"><span class="cite-bracket">[</span>52<span class="cite-bracket">]</span></a></sup> most chemistry is not about isolated gaseous atoms,<sup id="cite_ref-69" class="reference"><a href="#cite_note-69"><span class="cite-bracket">[</span>60<span class="cite-bracket">]</span></a></sup> and the various configurations are so close in energy to each other<sup id="cite_ref-Petrucci328_57-1" class="reference"><a href="#cite_note-Petrucci328-57"><span class="cite-bracket">[</span>50<span class="cite-bracket">]</span></a></sup> that the presence of a nearby atom can shift the balance.<sup id="cite_ref-FIII19_44-8" class="reference"><a href="#cite_note-FIII19-44"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup> Therefore, the periodic table ignores them and considers only idealized configurations.<sup id="cite_ref-Jensen2009_43-1" class="reference"><a href="#cite_note-Jensen2009-43"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup> </p><p>At <a href="/wiki/Zinc" title="Zinc">zinc</a> ([Ar] 3d<sup>10</sup> 4s<sup>2</sup>), the 3d orbitals are completely filled with a total of ten electrons.<sup id="cite_ref-FIII19_44-9" class="reference"><a href="#cite_note-FIII19-44"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-jensenlaw_66-4" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> Next come the 4p orbitals, completing the row, which are filled progressively by <a href="/wiki/Gallium" title="Gallium">gallium</a> ([Ar] 3d<sup>10</sup> 4s<sup>2</sup> 4p<sup>1</sup>) through <a href="/wiki/Krypton" title="Krypton">krypton</a> ([Ar] 3d<sup>10</sup> 4s<sup>2</sup> 4p<sup>6</sup>), in a manner analogous to the previous p-block elements.<sup id="cite_ref-FIII19_44-10" class="reference"><a href="#cite_note-FIII19-44"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-jensenlaw_66-5" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> From gallium onwards, the 3d orbitals form part of the electronic core, and no longer participate in chemistry.<sup id="cite_ref-KW_64-1" class="reference"><a href="#cite_note-KW-64"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup> The s- and p-block elements, which fill their outer shells, are called <a href="/wiki/Main-group_element" title="Main-group element">main-group elements</a>; the d-block elements (coloured blue below), which fill an inner shell, are called <a href="/wiki/Transition_element" class="mw-redirect" title="Transition element">transition elements</a> (or transition metals, since they are all metals).<sup id="cite_ref-Petrucci326_70-0" class="reference"><a href="#cite_note-Petrucci326-70"><span class="cite-bracket">[</span>61<span class="cite-bracket">]</span></a></sup> </p><p>The next eighteen elements fill the 5s orbitals (<a href="/wiki/Rubidium" title="Rubidium">rubidium</a> and <a href="/wiki/Strontium" title="Strontium">strontium</a>), then 4d (<a href="/wiki/Yttrium" title="Yttrium">yttrium</a> through <a href="/wiki/Cadmium" title="Cadmium">cadmium</a>, again with a few anomalies along the way), and then 5p (<a href="/wiki/Indium" title="Indium">indium</a> through <a href="/wiki/Xenon" title="Xenon">xenon</a>).<sup id="cite_ref-Petrucci331_34-7" class="reference"><a href="#cite_note-Petrucci331-34"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-jensenlaw_66-6" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> Again, from indium onward the 4d orbitals are in the core.<sup id="cite_ref-jensenlaw_66-7" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-71" class="reference"><a href="#cite_note-71"><span class="cite-bracket">[</span>62<span class="cite-bracket">]</span></a></sup> Hence the fifth row has the same structure as the fourth.<sup id="cite_ref-Petrucci331_34-8" class="reference"><a href="#cite_note-Petrucci331-34"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> </p> <table class="wikitable" style="margin:auto;"> <tbody><tr> <td bgcolor="#ff9999">1<br /><a href="/wiki/Hydrogen" title="Hydrogen">H</a> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td bgcolor="#ff9999">2<br /><a href="/wiki/Helium" title="Helium">He</a> </td> <td>2×1 = <b>2</b> elements<br /><span style="background:#ff9999; display:inline-block;">1s</span> <span style="display:inline-block;"><span style="visibility:hidden;color:transparent;">0d</span></span> <span style="display:inline-block;"><span style="visibility:hidden;color:transparent;">0p</span></span> </td></tr> <tr> <td bgcolor="#ff9999">3<br /><a href="/wiki/Lithium" title="Lithium">Li</a> </td> <td bgcolor="#ff9999">4<br /><a href="/wiki/Beryllium" title="Beryllium">Be</a> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td bgcolor="#fdff8c">5<br /><a href="/wiki/Boron" title="Boron">B</a> </td> <td bgcolor="#fdff8c">6<br /><a href="/wiki/Carbon" title="Carbon">C</a> </td> <td bgcolor="#fdff8c">7<br /><a href="/wiki/Nitrogen" title="Nitrogen">N</a> </td> <td bgcolor="#fdff8c">8<br /><a href="/wiki/Oxygen" title="Oxygen">O</a> </td> <td bgcolor="#fdff8c">9<br /><a href="/wiki/Fluorine" title="Fluorine">F</a> </td> <td bgcolor="#fdff8c">10<br /><a href="/wiki/Neon" title="Neon">Ne</a> </td> <td>2×(1+3) = <b>8</b> elements<br /><span style="background:#ff9999; display:inline-block;">2s</span> <span style="display:inline-block;"><span style="visibility:hidden;color:transparent;">0d</span></span> <span style="background:#fdff8c; display:inline-block;">2p</span> </td></tr> <tr> <td bgcolor="#ff9999">11<br /><a href="/wiki/Sodium" title="Sodium">Na</a> </td> <td bgcolor="#ff9999">12<br /><a href="/wiki/Magnesium" title="Magnesium">Mg</a> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td bgcolor="#fdff8c">13<br /><a href="/wiki/Aluminium" title="Aluminium">Al</a> </td> <td bgcolor="#fdff8c">14<br /><a href="/wiki/Silicon" title="Silicon">Si</a> </td> <td bgcolor="#fdff8c">15<br /><a href="/wiki/Phosphorus" title="Phosphorus">P</a> </td> <td bgcolor="#fdff8c">16<br /><a href="/wiki/Sulfur" title="Sulfur">S</a> </td> <td bgcolor="#fdff8c">17<br /><a href="/wiki/Chlorine" title="Chlorine">Cl</a> </td> <td bgcolor="#fdff8c">18<br /><a href="/wiki/Argon" title="Argon">Ar</a> </td> <td>2×(1+3) = <b>8</b> elements<br /><span style="background:#ff9999; display:inline-block;">3s</span> <span style="display:inline-block;"><span style="visibility:hidden;color:transparent;">0d</span></span> <span style="background:#fdff8c; display:inline-block;">3p</span> </td></tr> <tr> <td bgcolor="#ff9999">19<br /><a href="/wiki/Potassium" title="Potassium">K</a> </td> <td bgcolor="#ff9999">20<br /><a href="/wiki/Calcium" title="Calcium">Ca</a> </td> <td bgcolor="#99ccff">21<br /><a href="/wiki/Scandium" title="Scandium">Sc</a> </td> <td bgcolor="#99ccff">22<br /><a href="/wiki/Titanium" title="Titanium">Ti</a> </td> <td bgcolor="#99ccff">23<br /><a href="/wiki/Vanadium" title="Vanadium">V</a> </td> <td bgcolor="#99ccff">24<br /><a href="/wiki/Chromium" title="Chromium">Cr</a> </td> <td bgcolor="#99ccff">25<br /><a href="/wiki/Manganese" title="Manganese">Mn</a> </td> <td bgcolor="#99ccff">26<br /><a href="/wiki/Iron" title="Iron">Fe</a> </td> <td bgcolor="#99ccff">27<br /><a href="/wiki/Cobalt" title="Cobalt">Co</a> </td> <td bgcolor="#99ccff">28<br /><a href="/wiki/Nickel" title="Nickel">Ni</a> </td> <td bgcolor="#99ccff">29<br /><a href="/wiki/Copper" title="Copper">Cu</a> </td> <td bgcolor="#99ccff">30<br /><a href="/wiki/Zinc" title="Zinc">Zn</a> </td> <td bgcolor="#fdff8c">31<br /><a href="/wiki/Gallium" title="Gallium">Ga</a> </td> <td bgcolor="#fdff8c">32<br /><a href="/wiki/Germanium" title="Germanium">Ge</a> </td> <td bgcolor="#fdff8c">33<br /><a href="/wiki/Arsenic" title="Arsenic">As</a> </td> <td bgcolor="#fdff8c">34<br /><a href="/wiki/Selenium" title="Selenium">Se</a> </td> <td bgcolor="#fdff8c">35<br /><a href="/wiki/Bromine" title="Bromine">Br</a> </td> <td bgcolor="#fdff8c">36<br /><a href="/wiki/Krypton" title="Krypton">Kr</a> </td> <td><span class="nowrap">2×(1+3+5) = <b>18</b> elements</span><br /><span style="background:#ff9999; display:inline-block;">4s</span> <span style="background:#99ccff; display:inline-block;">3d</span> <span style="background:#fdff8c; display:inline-block;">4p</span> </td></tr> <tr> <td bgcolor="#ff9999">37<br /><a href="/wiki/Rubidium" title="Rubidium">Rb</a> </td> <td bgcolor="#ff9999">38<br /><a href="/wiki/Strontium" title="Strontium">Sr</a> </td> <td bgcolor="#99ccff">39<br /><a href="/wiki/Yttrium" title="Yttrium">Y</a> </td> <td bgcolor="#99ccff">40<br /><a href="/wiki/Zirconium" title="Zirconium">Zr</a> </td> <td bgcolor="#99ccff">41<br /><a href="/wiki/Niobium" title="Niobium">Nb</a> </td> <td bgcolor="#99ccff">42<br /><a href="/wiki/Molybdenum" title="Molybdenum">Mo</a> </td> <td bgcolor="#99ccff">43<br /><a href="/wiki/Technetium" title="Technetium">Tc</a> </td> <td bgcolor="#99ccff">44<br /><a href="/wiki/Ruthenium" title="Ruthenium">Ru</a> </td> <td bgcolor="#99ccff">45<br /><a href="/wiki/Rhodium" title="Rhodium">Rh</a> </td> <td bgcolor="#99ccff">46<br /><a href="/wiki/Palladium" title="Palladium">Pd</a> </td> <td bgcolor="#99ccff">47<br /><a href="/wiki/Silver" title="Silver">Ag</a> </td> <td bgcolor="#99ccff">48<br /><a href="/wiki/Cadmium" title="Cadmium">Cd</a> </td> <td bgcolor="#fdff8c">49<br /><a href="/wiki/Indium" title="Indium">In</a> </td> <td bgcolor="#fdff8c">50<br /><a href="/wiki/Tin" title="Tin">Sn</a> </td> <td bgcolor="#fdff8c">51<br /><a href="/wiki/Antimony" title="Antimony">Sb</a> </td> <td bgcolor="#fdff8c">52<br /><a href="/wiki/Tellurium" title="Tellurium">Te</a> </td> <td bgcolor="#fdff8c">53<br /><a href="/wiki/Iodine" title="Iodine">I</a> </td> <td bgcolor="#fdff8c">54<br /><a href="/wiki/Xenon" title="Xenon">Xe</a> </td> <td>2×(1+3+5) = <b>18</b> elements<br /><span style="background:#ff9999; display:inline-block;">5s</span> <span style="background:#99ccff; display:inline-block;">4d</span> <span style="background:#fdff8c; display:inline-block;">5p</span> </td></tr></tbody></table> <p>The sixth row of the table likewise starts with two s-block elements: <a href="/wiki/Caesium" title="Caesium">caesium</a> and <a href="/wiki/Barium" title="Barium">barium</a>.<sup id="cite_ref-jensenlaw_66-8" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> After this, the first f-block elements (coloured green below) begin to appear, starting with <a href="/wiki/Lanthanum" title="Lanthanum">lanthanum</a>. These are sometimes termed inner transition elements.<sup id="cite_ref-Petrucci326_70-1" class="reference"><a href="#cite_note-Petrucci326-70"><span class="cite-bracket">[</span>61<span class="cite-bracket">]</span></a></sup> As there are now not only 4f but also 5d and 6s subshells at similar energies, competition occurs once again with many irregular configurations;<sup id="cite_ref-Petrucci328_57-2" class="reference"><a href="#cite_note-Petrucci328-57"><span class="cite-bracket">[</span>50<span class="cite-bracket">]</span></a></sup> this resulted in some dispute about where exactly the f-block is supposed to begin, but most who study the matter agree that it starts at lanthanum in accordance with the Aufbau principle.<sup id="cite_ref-Jensen2015_31-1" class="reference"><a href="#cite_note-Jensen2015-31"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup> Even though lanthanum does not itself fill the 4f subshell as a single atom, because of repulsion between electrons,<sup id="cite_ref-Jorgensen_59-4" class="reference"><a href="#cite_note-Jorgensen-59"><span class="cite-bracket">[</span>52<span class="cite-bracket">]</span></a></sup> its 4f orbitals are low enough in energy to participate in chemistry.<sup id="cite_ref-Hamilton_72-0" class="reference"><a href="#cite_note-Hamilton-72"><span class="cite-bracket">[</span>63<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-elyashevich_60-1" class="reference"><a href="#cite_note-elyashevich-60"><span class="cite-bracket">[</span>53<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Cp3Ln_73-0" class="reference"><a href="#cite_note-Cp3Ln-73"><span class="cite-bracket">[</span>64<span class="cite-bracket">]</span></a></sup> At <a href="/wiki/Ytterbium" title="Ytterbium">ytterbium</a>, the seven 4f orbitals are completely filled with fourteen electrons; thereafter, a series of ten transition elements (<a href="/wiki/Lutetium" title="Lutetium">lutetium</a> through <a href="/wiki/Mercury_(element)" title="Mercury (element)">mercury</a>) follows,<sup id="cite_ref-jensenlaw_66-9" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-JensenLr_74-0" class="reference"><a href="#cite_note-JensenLr-74"><span class="cite-bracket">[</span>65<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-75" class="reference"><a href="#cite_note-75"><span class="cite-bracket">[</span>66<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-LaF3_76-0" class="reference"><a href="#cite_note-LaF3-76"><span class="cite-bracket">[</span>67<span class="cite-bracket">]</span></a></sup> and finally six main-group elements (<a href="/wiki/Thallium" title="Thallium">thallium</a> through <a href="/wiki/Radon" title="Radon">radon</a>) complete the period.<sup id="cite_ref-jensenlaw_66-10" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Pyykko_77-0" class="reference"><a href="#cite_note-Pyykko-77"><span class="cite-bracket">[</span>68<span class="cite-bracket">]</span></a></sup> From lutetium onwards the 4f orbitals are in the core,<sup id="cite_ref-jensenlaw_66-11" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Cp3Ln_73-1" class="reference"><a href="#cite_note-Cp3Ln-73"><span class="cite-bracket">[</span>64<span class="cite-bracket">]</span></a></sup> and from thallium onwards so are the 5d orbitals.<sup id="cite_ref-jensenlaw_66-12" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-KW_64-2" class="reference"><a href="#cite_note-KW-64"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-78" class="reference"><a href="#cite_note-78"><span class="cite-bracket">[</span>69<span class="cite-bracket">]</span></a></sup> </p><p>The seventh row is analogous to the sixth row: 7s fills (<a href="/wiki/Francium" title="Francium">francium</a> and <a href="/wiki/Radium" title="Radium">radium</a>), then 5f (<a href="/wiki/Actinium" title="Actinium">actinium</a> to <a href="/wiki/Nobelium" title="Nobelium">nobelium</a>), then 6d (<a href="/wiki/Lawrencium" title="Lawrencium">lawrencium</a> to <a href="/wiki/Copernicium" title="Copernicium">copernicium</a>), and finally 7p (<a href="/wiki/Nihonium" title="Nihonium">nihonium</a> to <a href="/wiki/Oganesson" title="Oganesson">oganesson</a>).<sup id="cite_ref-jensenlaw_66-13" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> Starting from lawrencium the 5f orbitals are in the core,<sup id="cite_ref-jensenlaw_66-14" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> and probably the 6d orbitals join the core starting from nihonium.<sup id="cite_ref-jensenlaw_66-15" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-VI_79-0" class="reference"><a href="#cite_note-VI-79"><span class="cite-bracket">[</span>70<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-81" class="reference"><a href="#cite_note-81"><span class="cite-bracket">[</span>j<span class="cite-bracket">]</span></a></sup> Again there are a few anomalies along the way:<sup id="cite_ref-Petrucci331_34-9" class="reference"><a href="#cite_note-Petrucci331-34"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> for example, as single atoms neither actinium nor <a href="/wiki/Thorium" title="Thorium">thorium</a> actually fills the 5f subshell, and lawrencium does not fill the 6d shell, but all these subshells can still become filled in chemical environments.<sup id="cite_ref-82" class="reference"><a href="#cite_note-82"><span class="cite-bracket">[</span>72<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Johansson_83-0" class="reference"><a href="#cite_note-Johansson-83"><span class="cite-bracket">[</span>73<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-XuPyykko_84-0" class="reference"><a href="#cite_note-XuPyykko-84"><span class="cite-bracket">[</span>74<span class="cite-bracket">]</span></a></sup> For a very long time, the seventh row was incomplete as most of its elements do not occur in nature. The missing <a href="/wiki/Transuranic_element" class="mw-redirect" title="Transuranic element">elements beyond uranium</a> started to be synthesized in the laboratory in 1940, when neptunium was made.<sup id="cite_ref-Scerri354_85-0" class="reference"><a href="#cite_note-Scerri354-85"><span class="cite-bracket">[</span>75<span class="cite-bracket">]</span></a></sup> (However, the first element to be discovered by synthesis rather than in nature was technetium in 1937.) The row was completed with the synthesis of <a href="/wiki/Tennessine" title="Tennessine">tennessine</a> in 2010<sup id="cite_ref-117s_86-0" class="reference"><a href="#cite_note-117s-86"><span class="cite-bracket">[</span>76<span class="cite-bracket">]</span></a></sup> (the last element <a href="/wiki/Oganesson" title="Oganesson">oganesson</a> had already been made in 2002),<sup id="cite_ref-pp2002_87-0" class="reference"><a href="#cite_note-pp2002-87"><span class="cite-bracket">[</span>77<span class="cite-bracket">]</span></a></sup> and the last elements in this seventh row were given names in 2016.<sup id="cite_ref-IUPAC-20161130_88-0" class="reference"><a href="#cite_note-IUPAC-20161130-88"><span class="cite-bracket">[</span>78<span class="cite-bracket">]</span></a></sup> </p> <div style="overflow-x:auto"> <table class="wikitable" style="margin:auto;"> <tbody><tr> <td bgcolor="#ff9999">1<br /><a href="/wiki/Hydrogen" title="Hydrogen">H</a> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td bgcolor="#ff9999">2<br /><a href="/wiki/Helium" title="Helium">He</a> </td> <td>2×1 = <b>2</b> elements<br /><span style="background:#ff9999; display:inline-block;">1s</span> <span style="display:inline-block;"><span style="visibility:hidden;color:transparent;">0f</span></span> <span style="display:inline-block;"><span style="visibility:hidden;color:transparent;">0d</span></span> <span style="display:inline-block;"><span style="visibility:hidden;color:transparent;">0p</span></span> </td></tr> <tr> <td bgcolor="#ff9999">3<br /><a href="/wiki/Lithium" title="Lithium">Li</a> </td> <td bgcolor="#ff9999">4<br /><a href="/wiki/Beryllium" title="Beryllium">Be</a> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td bgcolor="#fdff8c">5<br /><a href="/wiki/Boron" title="Boron">B</a> </td> <td bgcolor="#fdff8c">6<br /><a href="/wiki/Carbon" title="Carbon">C</a> </td> <td bgcolor="#fdff8c">7<br /><a href="/wiki/Nitrogen" title="Nitrogen">N</a> </td> <td bgcolor="#fdff8c">8<br /><a href="/wiki/Oxygen" title="Oxygen">O</a> </td> <td bgcolor="#fdff8c">9<br /><a href="/wiki/Fluorine" title="Fluorine">F</a> </td> <td bgcolor="#fdff8c">10<br /><a href="/wiki/Neon" title="Neon">Ne</a> </td> <td>2×(1+3) = <b>8</b> elements<br /><span style="background:#ff9999; display:inline-block;">2s</span> <span style="display:inline-block;"><span style="visibility:hidden;color:transparent;">0f</span></span> <span style="display:inline-block;"><span style="visibility:hidden;color:transparent;">0d</span></span> <span style="background:#fdff8c; display:inline-block;">2p</span> </td></tr> <tr> <td bgcolor="#ff9999">11<br /><a href="/wiki/Sodium" title="Sodium">Na</a> </td> <td bgcolor="#ff9999">12<br /><a href="/wiki/Magnesium" title="Magnesium">Mg</a> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td bgcolor="#fdff8c">13<br /><a href="/wiki/Aluminium" title="Aluminium">Al</a> </td> <td bgcolor="#fdff8c">14<br /><a href="/wiki/Silicon" title="Silicon">Si</a> </td> <td bgcolor="#fdff8c">15<br /><a href="/wiki/Phosphorus" title="Phosphorus">P</a> </td> <td bgcolor="#fdff8c">16<br /><a href="/wiki/Sulfur" title="Sulfur">S</a> </td> <td bgcolor="#fdff8c">17<br /><a href="/wiki/Chlorine" title="Chlorine">Cl</a> </td> <td bgcolor="#fdff8c">18<br /><a href="/wiki/Argon" title="Argon">Ar</a> </td> <td>2×(1+3) = <b>8</b> elements<br /><span style="background:#ff9999; display:inline-block;">3s</span> <span style="display:inline-block;"><span style="visibility:hidden;color:transparent;">0f</span></span> <span style="display:inline-block;"><span style="visibility:hidden;color:transparent;">0d</span></span> <span style="background:#fdff8c; display:inline-block;">3p</span> </td></tr> <tr> <td bgcolor="#ff9999">19<br /><a href="/wiki/Potassium" title="Potassium">K</a> </td> <td bgcolor="#ff9999">20<br /><a href="/wiki/Calcium" title="Calcium">Ca</a> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td bgcolor="#99ccff">21<br /><a href="/wiki/Scandium" title="Scandium">Sc</a> </td> <td bgcolor="#99ccff">22<br /><a href="/wiki/Titanium" title="Titanium">Ti</a> </td> <td bgcolor="#99ccff">23<br /><a href="/wiki/Vanadium" title="Vanadium">V</a> </td> <td bgcolor="#99ccff">24<br /><a href="/wiki/Chromium" title="Chromium">Cr</a> </td> <td bgcolor="#99ccff">25<br /><a href="/wiki/Manganese" title="Manganese">Mn</a> </td> <td bgcolor="#99ccff">26<br /><a href="/wiki/Iron" title="Iron">Fe</a> </td> <td bgcolor="#99ccff">27<br /><a href="/wiki/Cobalt" title="Cobalt">Co</a> </td> <td bgcolor="#99ccff">28<br /><a href="/wiki/Nickel" title="Nickel">Ni</a> </td> <td bgcolor="#99ccff">29<br /><a href="/wiki/Copper" title="Copper">Cu</a> </td> <td bgcolor="#99ccff">30<br /><a href="/wiki/Zinc" title="Zinc">Zn</a> </td> <td bgcolor="#fdff8c">31<br /><a href="/wiki/Gallium" title="Gallium">Ga</a> </td> <td bgcolor="#fdff8c">32<br /><a href="/wiki/Germanium" title="Germanium">Ge</a> </td> <td bgcolor="#fdff8c">33<br /><a href="/wiki/Arsenic" title="Arsenic">As</a> </td> <td bgcolor="#fdff8c">34<br /><a href="/wiki/Selenium" title="Selenium">Se</a> </td> <td bgcolor="#fdff8c">35<br /><a href="/wiki/Bromine" title="Bromine">Br</a> </td> <td bgcolor="#fdff8c">36<br /><a href="/wiki/Krypton" title="Krypton">Kr</a> </td> <td>2×(1+3+5) = <b>18</b> elements<br /><span style="background:#ff9999; display:inline-block;">4s</span> <span style="display:inline-block;"><span style="visibility:hidden;color:transparent;">0f</span></span> <span style="background:#99ccff; display:inline-block;">3d</span> <span style="background:#fdff8c; display:inline-block;">4p</span> </td></tr> <tr> <td bgcolor="#ff9999">37<br /><a href="/wiki/Rubidium" title="Rubidium">Rb</a> </td> <td bgcolor="#ff9999">38<br /><a href="/wiki/Strontium" title="Strontium">Sr</a> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td bgcolor="#99ccff">39<br /><a href="/wiki/Yttrium" title="Yttrium">Y</a> </td> <td bgcolor="#99ccff">40<br /><a href="/wiki/Zirconium" title="Zirconium">Zr</a> </td> <td bgcolor="#99ccff">41<br /><a href="/wiki/Niobium" title="Niobium">Nb</a> </td> <td bgcolor="#99ccff">42<br /><a href="/wiki/Molybdenum" title="Molybdenum">Mo</a> </td> <td bgcolor="#99ccff">43<br /><a href="/wiki/Technetium" title="Technetium">Tc</a> </td> <td bgcolor="#99ccff">44<br /><a href="/wiki/Ruthenium" title="Ruthenium">Ru</a> </td> <td bgcolor="#99ccff">45<br /><a href="/wiki/Rhodium" title="Rhodium">Rh</a> </td> <td bgcolor="#99ccff">46<br /><a href="/wiki/Palladium" title="Palladium">Pd</a> </td> <td bgcolor="#99ccff">47<br /><a href="/wiki/Silver" title="Silver">Ag</a> </td> <td bgcolor="#99ccff">48<br /><a href="/wiki/Cadmium" title="Cadmium">Cd</a> </td> <td bgcolor="#fdff8c">49<br /><a href="/wiki/Indium" title="Indium">In</a> </td> <td bgcolor="#fdff8c">50<br /><a href="/wiki/Tin" title="Tin">Sn</a> </td> <td bgcolor="#fdff8c">51<br /><a href="/wiki/Antimony" title="Antimony">Sb</a> </td> <td bgcolor="#fdff8c">52<br /><a href="/wiki/Tellurium" title="Tellurium">Te</a> </td> <td bgcolor="#fdff8c">53<br /><a href="/wiki/Iodine" title="Iodine">I</a> </td> <td bgcolor="#fdff8c">54<br /><a href="/wiki/Xenon" title="Xenon">Xe</a> </td> <td>2×(1+3+5) = <b>18</b> elements<br /><span style="background:#ff9999; display:inline-block;">5s</span> <span style="display:inline-block;"><span style="visibility:hidden;color:transparent;">0f</span></span> <span style="background:#99ccff; display:inline-block;">4d</span> <span style="background:#fdff8c; display:inline-block;">5p</span> </td></tr> <tr> <td bgcolor="#ff9999">55<br /><a href="/wiki/Caesium" title="Caesium">Cs</a> </td> <td bgcolor="#ff9999">56<br /><a href="/wiki/Barium" title="Barium">Ba</a> </td> <td bgcolor="#9bff99">57<br /><a href="/wiki/Lanthanum" title="Lanthanum">La</a> </td> <td bgcolor="#9bff99">58<br /><a href="/wiki/Cerium" title="Cerium">Ce</a> </td> <td bgcolor="#9bff99">59<br /><a href="/wiki/Praseodymium" title="Praseodymium">Pr</a> </td> <td bgcolor="#9bff99">60<br /><a href="/wiki/Neodymium" title="Neodymium">Nd</a> </td> <td bgcolor="#9bff99">61<br /><a href="/wiki/Promethium" title="Promethium">Pm</a> </td> <td bgcolor="#9bff99">62<br /><a href="/wiki/Samarium" title="Samarium">Sm</a> </td> <td bgcolor="#9bff99">63<br /><a href="/wiki/Europium" title="Europium">Eu</a> </td> <td bgcolor="#9bff99">64<br /><a href="/wiki/Gadolinium" title="Gadolinium">Gd</a> </td> <td bgcolor="#9bff99">65<br /><a href="/wiki/Terbium" title="Terbium">Tb</a> </td> <td bgcolor="#9bff99">66<br /><a href="/wiki/Dysprosium" title="Dysprosium">Dy</a> </td> <td bgcolor="#9bff99">67<br /><a href="/wiki/Holmium" title="Holmium">Ho</a> </td> <td bgcolor="#9bff99">68<br /><a href="/wiki/Erbium" title="Erbium">Er</a> </td> <td bgcolor="#9bff99">69<br /><a href="/wiki/Thulium" title="Thulium">Tm</a> </td> <td bgcolor="#9bff99">70<br /><a href="/wiki/Ytterbium" title="Ytterbium">Yb</a> </td> <td bgcolor="#99ccff">71<br /><a href="/wiki/Lutetium" title="Lutetium">Lu</a> </td> <td bgcolor="#99ccff">72<br /><a href="/wiki/Hafnium" title="Hafnium">Hf</a> </td> <td bgcolor="#99ccff">73<br /><a href="/wiki/Tantalum" title="Tantalum">Ta</a> </td> <td bgcolor="#99ccff">74<br /><a href="/wiki/Tungsten" title="Tungsten">W</a> </td> <td bgcolor="#99ccff">75<br /><a href="/wiki/Rhenium" title="Rhenium">Re</a> </td> <td bgcolor="#99ccff">76<br /><a href="/wiki/Osmium" title="Osmium">Os</a> </td> <td bgcolor="#99ccff">77<br /><a href="/wiki/Iridium" title="Iridium">Ir</a> </td> <td bgcolor="#99ccff">78<br /><a href="/wiki/Platinum" title="Platinum">Pt</a> </td> <td bgcolor="#99ccff">79<br /><a href="/wiki/Gold" title="Gold">Au</a> </td> <td bgcolor="#99ccff">80<br /><a href="/wiki/Mercury_(element)" title="Mercury (element)">Hg</a> </td> <td bgcolor="#fdff8c">81<br /><a href="/wiki/Thallium" title="Thallium">Tl</a> </td> <td bgcolor="#fdff8c">82<br /><a href="/wiki/Lead" title="Lead">Pb</a> </td> <td bgcolor="#fdff8c">83<br /><a href="/wiki/Bismuth" title="Bismuth">Bi</a> </td> <td bgcolor="#fdff8c">84<br /><a href="/wiki/Polonium" title="Polonium">Po</a> </td> <td bgcolor="#fdff8c">85<br /><a href="/wiki/Astatine" title="Astatine">At</a> </td> <td bgcolor="#fdff8c">86<br /><a href="/wiki/Radon" title="Radon">Rn</a> </td> <td><span class="nowrap">2×(1+3+5+7) = <b>32</b> elements</span><br /><span class="nowrap"><span style="background:#ff9999; display:inline-block;">6s</span> <span style="background:#9bff99; display:inline-block;">4f</span> <span style="background:#99ccff; display:inline-block;">5d</span> <span style="background:#fdff8c; display:inline-block;">6p</span></span> </td></tr> <tr> <td bgcolor="#ff9999">87<br /><a href="/wiki/Francium" title="Francium">Fr</a> </td> <td bgcolor="#ff9999">88<br /><a href="/wiki/Radium" title="Radium">Ra</a> </td> <td bgcolor="#9bff99">89<br /><a href="/wiki/Actinium" title="Actinium">Ac</a> </td> <td bgcolor="#9bff99">90<br /><a href="/wiki/Thorium" title="Thorium">Th</a> </td> <td bgcolor="#9bff99">91<br /><a href="/wiki/Protactinium" title="Protactinium">Pa</a> </td> <td bgcolor="#9bff99">92<br /><a href="/wiki/Uranium" title="Uranium">U</a> </td> <td bgcolor="#9bff99">93<br /><a href="/wiki/Neptunium" title="Neptunium">Np</a> </td> <td bgcolor="#9bff99">94<br /><a href="/wiki/Plutonium" title="Plutonium">Pu</a> </td> <td bgcolor="#9bff99">95<br /><a href="/wiki/Americium" title="Americium">Am</a> </td> <td bgcolor="#9bff99">96<br /><a href="/wiki/Curium" title="Curium">Cm</a> </td> <td bgcolor="#9bff99">97<br /><a href="/wiki/Berkelium" title="Berkelium">Bk</a> </td> <td bgcolor="#9bff99">98<br /><a href="/wiki/Californium" title="Californium">Cf</a> </td> <td bgcolor="#9bff99">99<br /><a href="/wiki/Einsteinium" title="Einsteinium">Es</a> </td> <td bgcolor="#9bff99">100<br /><a href="/wiki/Fermium" title="Fermium">Fm</a> </td> <td bgcolor="#9bff99">101<br /><a href="/wiki/Mendelevium" title="Mendelevium">Md</a> </td> <td bgcolor="#9bff99">102<br /><a href="/wiki/Nobelium" title="Nobelium">No</a> </td> <td bgcolor="#99ccff">103<br /><a href="/wiki/Lawrencium" title="Lawrencium">Lr</a> </td> <td bgcolor="#99ccff">104<br /><a href="/wiki/Rutherfordium" title="Rutherfordium">Rf</a> </td> <td bgcolor="#99ccff">105<br /><a href="/wiki/Dubnium" title="Dubnium">Db</a> </td> <td bgcolor="#99ccff">106<br /><a href="/wiki/Seaborgium" title="Seaborgium">Sg</a> </td> <td bgcolor="#99ccff">107<br /><a href="/wiki/Bohrium" title="Bohrium">Bh</a> </td> <td bgcolor="#99ccff">108<br /><a href="/wiki/Hassium" title="Hassium">Hs</a> </td> <td bgcolor="#99ccff">109<br /><a href="/wiki/Meitnerium" title="Meitnerium">Mt</a> </td> <td bgcolor="#99ccff">110<br /><a href="/wiki/Darmstadtium" title="Darmstadtium">Ds</a> </td> <td bgcolor="#99ccff">111<br /><a href="/wiki/Roentgenium" title="Roentgenium">Rg</a> </td> <td bgcolor="#99ccff">112<br /><a href="/wiki/Copernicium" title="Copernicium">Cn</a> </td> <td bgcolor="#fdff8c">113<br /><a href="/wiki/Nihonium" title="Nihonium">Nh</a> </td> <td bgcolor="#fdff8c">114<br /><a href="/wiki/Flerovium" title="Flerovium">Fl</a> </td> <td bgcolor="#fdff8c">115<br /><a href="/wiki/Moscovium" title="Moscovium">Mc</a> </td> <td bgcolor="#fdff8c">116<br /><a href="/wiki/Livermorium" title="Livermorium">Lv</a> </td> <td bgcolor="#fdff8c">117<br /><a href="/wiki/Tennessine" title="Tennessine">Ts</a> </td> <td bgcolor="#fdff8c">118<br /><a href="/wiki/Oganesson" title="Oganesson">Og</a> </td> <td>2×(1+3+5+7) = <b>32</b> elements<br /><span style="background:#ff9999; display:inline-block;">7s</span> <span style="background:#9bff99; display:inline-block;">5f</span> <span style="background:#99ccff; display:inline-block;">6d</span> <span style="background:#fdff8c; display:inline-block;">7p</span> </td></tr></tbody></table> </div> <p>This completes the modern periodic table, with all seven rows completely filled to capacity.<sup id="cite_ref-IUPAC-20161130_88-1" class="reference"><a href="#cite_note-IUPAC-20161130-88"><span class="cite-bracket">[</span>78<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Electron_configuration_table">Electron configuration table</h3></div> <p>The following table shows the electron configuration of a neutral gas-phase atom of each element. Different configurations can be favoured in different chemical environments.<sup id="cite_ref-Jorgensen_59-5" class="reference"><a href="#cite_note-Jorgensen-59"><span class="cite-bracket">[</span>52<span class="cite-bracket">]</span></a></sup> The main-group elements have entirely regular electron configurations; the transition and inner transition elements show twenty irregularities due to the aforementioned competition between subshells close in energy level. For the last ten elements (109–118), experimental data is lacking<sup id="cite_ref-89" class="reference"><a href="#cite_note-89"><span class="cite-bracket">[</span>79<span class="cite-bracket">]</span></a></sup> and therefore calculated configurations have been shown instead.<sup id="cite_ref-90" class="reference"><a href="#cite_note-90"><span class="cite-bracket">[</span>80<span class="cite-bracket">]</span></a></sup> Completely filled subshells have been greyed out. </p> <table class="mw-collapsible collapsed" style="line-height:120%; text-align:center; background:#f8f8f8; border:1px solid #a9a9a9; margin:0 auto; padding:2px;"> <tbody><tr> <th colspan="33" style="background:#d8d8d8; padding:2px 4px;"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-collapse navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Periodic_table_(electron_configuration)" title="Template:Periodic table (electron configuration)"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Periodic_table_(electron_configuration)" title="Template talk:Periodic table (electron configuration)"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Periodic_table_(electron_configuration)" title="Special:EditPage/Template:Periodic table (electron configuration)"><abbr title="Edit this template">e</abbr></a></li></ul></div><div class="navbar-ct-mini"><a href="/wiki/Electron_shell" title="Electron shell">Electron configurations</a> of the <a class="mw-selflink selflink">chemical elements</a> <style data-mw-deduplicate="TemplateStyles:r886047488">.mw-parser-output .nobold{font-weight:normal}</style><span class="nobold"><small>(neutral gaseous atoms in the ground state; predictions for elements 109–118)</small></span></div> </th></tr> <tr style="border-bottom:2px solid #f8f8f8;"> <th scope="row" style="text-align:right; width:2.5em"><small><a href="/wiki/Group_(periodic_table)" title="Group (periodic table)">Group</a>:</small> </th> <td style="background:#e8e8e8; width:2em;"><a href="/wiki/Alkali_metal" title="Alkali metal">1</a> </td> <td style="background:#f0f0f0; width:2em;"><a href="/wiki/Alkaline_earth_metal" title="Alkaline earth metal">2</a> </td> <th colspan="14">​ </th> <td style="background:#e8e8e8; width:2em;"><a href="/wiki/Group_3_element" title="Group 3 element">3</a> </td> <td style="background:#f0f0f0; width:2em;"><a href="/wiki/Group_4_element" title="Group 4 element">4</a> </td> <td style="background:#e8e8e8; width:2em;"><a href="/wiki/Group_5_element" title="Group 5 element">5</a> </td> <td style="background:#f0f0f0; width:2em;"><a href="/wiki/Group_6_element" title="Group 6 element">6</a> </td> <td style="background:#e8e8e8; width:2em;"><a href="/wiki/Group_7_element" title="Group 7 element">7</a> </td> <td style="background:#f0f0f0; width:2em;"><a href="/wiki/Group_8_element" title="Group 8 element">8</a> </td> <td style="background:#e8e8e8; width:2em;"><a href="/wiki/Group_9_element" title="Group 9 element">9</a> </td> <td style="background:#f0f0f0; width:2em;"><a href="/wiki/Group_10_element" title="Group 10 element">10</a> </td> <td style="background:#e8e8e8; width:2em;"><a href="/wiki/Group_11_element" title="Group 11 element">11</a> </td> <td style="background:#f0f0f0; width:2em;"><a href="/wiki/Group_12_element" title="Group 12 element">12</a> </td> <td style="background:#e8e8e8; width:2em;"><a href="/wiki/Boron_group" title="Boron group">13</a> </td> <td style="background:#f0f0f0; width:2em;"><a href="/wiki/Carbon_group" title="Carbon group">14</a> </td> <td style="background:#e8e8e8; width:2em;"><a href="/wiki/Pnictogen" title="Pnictogen">15</a> </td> <td style="background:#f0f0f0; width:2em;"><a href="/wiki/Chalcogen" title="Chalcogen">16</a> </td> <td style="background:#e8e8e8; width:2em;"><a href="/wiki/Halogen" title="Halogen">17</a> </td> <td style="background:#f0f0f0; width:2em;"><a href="/wiki/Noble_gas" title="Noble gas">18</a> </td></tr> <tr style="border-bottom:2px solid #f8f8f8;"> <td style="background:#e8e8e8; vertical-align:bottom">1s: </td> <td style="background:#ff9999;">1<br /><b><a href="/wiki/Hydrogen" title="Hydrogen">H</a></b><br />1 </td> <td colspan="30"> </td> <td style="background:#ff9999;">2<br /><b><a href="/wiki/Helium" title="Helium">He</a></b><br /><span style="color:gray">2</span> </td></tr> <tr style="border-bottom:2px solid #f8f8f8;"> <td style="background:#e8e8e8; vertical-align:bottom"><small style="color:gray">[He]</small><br />2s:<br />2p: </td> <td style="background:#ff9999;">3<br /><b><a href="/wiki/Lithium" title="Lithium">Li</a></b><br />1<br />- </td> <td style="background:#ff9999;">4<br /><b><a href="/wiki/Beryllium" title="Beryllium">Be</a></b><br /><span style="color:gray">2</span><br />- </td> <td colspan="24"> </td> <td style="background:#fdff8c;">5<br /><b><a href="/wiki/Boron" title="Boron">B</a></b><br /><span style="color:gray">2</span><br />1 </td> <td style="background:#fdff8c;">6<br /><b><a href="/wiki/Carbon" title="Carbon">C</a></b><br /><span style="color:gray">2</span><br />2 </td> <td style="background:#fdff8c;">7<br /><b><a href="/wiki/Nitrogen" title="Nitrogen">N</a></b><br /><span style="color:gray">2</span><br />3 </td> <td style="background:#fdff8c;">8<br /><b><a href="/wiki/Oxygen" title="Oxygen">O</a></b><br /><span style="color:gray">2</span><br />4 </td> <td style="background:#fdff8c;">9<br /><b><a href="/wiki/Fluorine" title="Fluorine">F</a></b><br /><span style="color:gray">2</span><br />5 </td> <td style="background:#fdff8c;">10<br /><b><a href="/wiki/Neon" title="Neon">Ne</a></b><br /><span style="color:gray">2<br />6</span> </td></tr> <tr style="border-bottom:2px solid #f8f8f8;"> <td style="background:#e8e8e8; vertical-align:bottom"><small style="color:gray">[Ne]</small><br />3s:<br />3p: </td> <td style="background:#ff9999;">11<br /><b><a href="/wiki/Sodium" title="Sodium">Na</a></b><br />1<br />- </td> <td style="background:#ff9999;">12<br /><b><a href="/wiki/Magnesium" title="Magnesium">Mg</a></b><br /><span style="color:gray">2</span><br />- </td> <td colspan="24"> </td> <td style="background:#fdff8c;">13<br /><b><a href="/wiki/Aluminium" title="Aluminium">Al</a></b><br /><span style="color:gray">2</span><br />1 </td> <td style="background:#fdff8c;">14<br /><b><a href="/wiki/Silicon" title="Silicon">Si</a></b><br /><span style="color:gray">2</span><br />2 </td> <td style="background:#fdff8c;">15<br /><b><a href="/wiki/Phosphorus" title="Phosphorus">P</a></b><br /><span style="color:gray">2</span><br />3 </td> <td style="background:#fdff8c;">16<br /><b><a href="/wiki/Sulfur" title="Sulfur">S</a></b><br /><span style="color:gray">2</span><br />4 </td> <td style="background:#fdff8c;">17<br /><b><a href="/wiki/Chlorine" title="Chlorine">Cl</a></b><br /><span style="color:gray">2</span><br />5 </td> <td style="background:#fdff8c;">18<br /><b><a href="/wiki/Argon" title="Argon">Ar</a></b><br /><span style="color:gray">2<br />6</span> </td></tr> <tr style="border-bottom:2px solid #f8f8f8;"> <td style="background:#e8e8e8; vertical-align:bottom"><small style="color:gray">[Ar]</small><br />4s:<br />3d:<br />4p: </td> <td style="background:#ff9999;">19<br /><b><a href="/wiki/Potassium" title="Potassium">K</a></b><br />1<br />-<br />- </td> <td style="background:#ff9999;">20<br /><b><a href="/wiki/Calcium" title="Calcium">Ca</a></b><br /><span style="color:gray">2</span><br />-<br />- </td> <td colspan="14"> </td> <td style="background:#99ccff;">21<br /><b><a href="/wiki/Scandium" title="Scandium">Sc</a></b><br /><span style="color:gray">2</span><br />1<br />- </td> <td style="background:#99ccff;">22<br /><b><a href="/wiki/Titanium" title="Titanium">Ti</a></b><br /><span style="color:gray">2</span><br />2<br />- </td> <td style="background:#99ccff;">23<br /><b><a href="/wiki/Vanadium" title="Vanadium">V</a></b><br /><span style="color:gray">2</span><br />3<br />- </td> <td style="background:#99ccff;">24<br /><b><a href="/wiki/Chromium" title="Chromium">Cr</a></b><br />1<br />5<br />- </td> <td style="background:#99ccff;">25<br /><b><a href="/wiki/Manganese" title="Manganese">Mn</a></b><br /><span style="color:gray">2</span><br />5<br />- </td> <td style="background:#99ccff;">26<br /><b><a href="/wiki/Iron" title="Iron">Fe</a></b><br /><span style="color:gray">2</span><br />6<br />- </td> <td style="background:#99ccff;">27<br /><b><a href="/wiki/Cobalt" title="Cobalt">Co</a></b><br /><span style="color:gray">2</span><br />7<br />- </td> <td style="background:#99ccff;">28<br /><b><a href="/wiki/Nickel" title="Nickel">Ni</a></b><br /><span style="color:gray">2</span><br />8<br />- </td> <td style="background:#99ccff;">29<br /><b><a href="/wiki/Copper" title="Copper">Cu</a></b><br />1<br /><span style="color:gray">10</span><br />- </td> <td style="background:#99ccff;">30<br /><b><a href="/wiki/Zinc" title="Zinc">Zn</a></b><br /><span style="color:gray">2<br />10</span><br />- </td> <td style="background:#fdff8c;">31<br /><b><a href="/wiki/Gallium" title="Gallium">Ga</a></b><br /><span style="color:gray">2<br />10</span><br />1 </td> <td style="background:#fdff8c;">32<br /><b><a href="/wiki/Germanium" title="Germanium">Ge</a></b><br /><span style="color:gray">2<br />10</span><br />2 </td> <td style="background:#fdff8c;">33<br /><b><a href="/wiki/Arsenic" title="Arsenic">As</a></b><br /><span style="color:gray">2<br />10</span><br />3 </td> <td style="background:#fdff8c;">34<br /><b><a href="/wiki/Selenium" title="Selenium">Se</a></b><br /><span style="color:gray">2<br />10</span><br />4 </td> <td style="background:#fdff8c;">35<br /><b><a href="/wiki/Bromine" title="Bromine">Br</a></b><br /><span style="color:gray">2<br />10</span><br />5 </td> <td style="background:#fdff8c;">36<br /><b><a href="/wiki/Krypton" title="Krypton">Kr</a></b><br /><span style="color:gray">2<br />10<br />6</span> </td></tr> <tr style="border-bottom:2px solid #f8f8f8;"> <td style="background:#e8e8e8; vertical-align:bottom"><small style="color:gray">[Kr]</small><br />5s:<br />4d:<br />5p: </td> <td style="background:#ff9999;">37<br /><b><a href="/wiki/Rubidium" title="Rubidium">Rb</a></b><br />1<br />-<br />- </td> <td style="background:#ff9999;">38<br /><b><a href="/wiki/Strontium" title="Strontium">Sr</a></b><br /><span style="color:gray">2</span><br />-<br />- </td> <td colspan="14"> </td> <td style="background:#99ccff;">39<br /><b><a href="/wiki/Yttrium" title="Yttrium">Y</a></b><br /><span style="color:gray">2</span><br />1<br />- </td> <td style="background:#99ccff;">40<br /><b><a href="/wiki/Zirconium" title="Zirconium">Zr</a></b><br /><span style="color:gray">2</span><br />2<br />- </td> <td style="background:#99ccff;">41<br /><b><a href="/wiki/Niobium" title="Niobium">Nb</a></b><br />1<br />4<br />- </td> <td style="background:#99ccff;">42<br /><b><a href="/wiki/Molybdenum" title="Molybdenum">Mo</a></b><br />1<br />5<br />- </td> <td style="background:#99ccff;">43<br /><b><a href="/wiki/Technetium" title="Technetium">Tc</a></b><br /><span style="color:gray">2</span><br />5<br />- </td> <td style="background:#99ccff;">44<br /><b><a href="/wiki/Ruthenium" title="Ruthenium">Ru</a></b><br />1<br />7<br />- </td> <td style="background:#99ccff;">45<br /><b><a href="/wiki/Rhodium" title="Rhodium">Rh</a></b><br />1<br />8<br />- </td> <td style="background:#99ccff;">46<br /><b><a href="/wiki/Palladium" title="Palladium">Pd</a></b><br />-<br /><span style="color:gray">10</span><br />- </td> <td style="background:#99ccff;">47<br /><b><a href="/wiki/Silver" title="Silver">Ag</a></b><br />1<br /><span style="color:gray">10</span><br />- </td> <td style="background:#99ccff;">48<br /><b><a href="/wiki/Cadmium" title="Cadmium">Cd</a></b><br /><span style="color:gray">2<br />10</span><br />- </td> <td style="background:#fdff8c;">49<br /><b><a href="/wiki/Indium" title="Indium">In</a></b><br /><span style="color:gray">2<br />10</span><br />1 </td> <td style="background:#fdff8c;">50<br /><b><a href="/wiki/Tin" title="Tin">Sn</a></b><br /><span style="color:gray">2<br />10</span><br />2 </td> <td style="background:#fdff8c;">51<br /><b><a href="/wiki/Antimony" title="Antimony">Sb</a></b><br /><span style="color:gray">2<br />10</span><br />3 </td> <td style="background:#fdff8c;">52<br /><b><a href="/wiki/Tellurium" title="Tellurium">Te</a></b><br /><span style="color:gray">2<br />10</span><br />4 </td> <td style="background:#fdff8c;">53<br /><b><a href="/wiki/Iodine" title="Iodine">I</a></b><br /><span style="color:gray">2<br />10</span><br />5 </td> <td style="background:#fdff8c;">54<br /><b><a href="/wiki/Xenon" title="Xenon">Xe</a></b><br /><span style="color:gray">2<br />10<br />6</span> </td></tr> <tr style="border-bottom:2px solid #f8f8f8;"> <td style="background:#e8e8e8; vertical-align:bottom"><small style="color:gray">[Xe]</small><br />6s:<br />4f:<br />5d:<br />6p: </td> <td style="background:#ff9999;">55<br /><b><a href="/wiki/Caesium" title="Caesium">Cs</a></b><br />1<br />-<br />-<br />- </td> <td style="background:#ff9999;">56<br /><b><a href="/wiki/Barium" title="Barium">Ba</a></b><br /><span style="color:gray">2</span><br />-<br />-<br />- </td> <td style="background:#9bff99; width:2em;">57<br /><b><a href="/wiki/Lanthanum" title="Lanthanum">La</a></b><br /><span style="color:gray">2</span><br />-<br />1<br />- </td> <td style="background:#9bff99; width:2em;">58<br /><b><a href="/wiki/Cerium" title="Cerium">Ce</a></b><br /><span style="color:gray">2</span><br />1<br />1<br />- </td> <td style="background:#9bff99; width:2em;">59<br /><b><a href="/wiki/Praseodymium" title="Praseodymium">Pr</a></b><br /><span style="color:gray">2</span><br />3<br />-<br />- </td> <td style="background:#9bff99; width:2em;">60<br /><b><a href="/wiki/Neodymium" title="Neodymium">Nd</a></b><br /><span style="color:gray">2</span><br />4<br />-<br />- </td> <td style="background:#9bff99; width:2em;">61<br /><b><a href="/wiki/Promethium" title="Promethium">Pm</a></b><br /><span style="color:gray">2</span><br />5<br />-<br />- </td> <td style="background:#9bff99; width:2em;">62<br /><b><a href="/wiki/Samarium" title="Samarium">Sm</a></b><br /><span style="color:gray">2</span><br />6<br />-<br />- </td> <td style="background:#9bff99; width:2em;">63<br /><b><a href="/wiki/Europium" title="Europium">Eu</a></b><br /><span style="color:gray">2</span><br />7<br />-<br />- </td> <td style="background:#9bff99; width:2em;">64<br /><b><a href="/wiki/Gadolinium" title="Gadolinium">Gd</a></b><br /><span style="color:gray">2</span><br />7<br />1<br />- </td> <td style="background:#9bff99; width:2em;">65<br /><b><a href="/wiki/Terbium" title="Terbium">Tb</a></b><br /><span style="color:gray">2</span><br />9<br />-<br />- </td> <td style="background:#9bff99; width:2em;">66<br /><b><a href="/wiki/Dysprosium" title="Dysprosium">Dy</a></b><br /><span style="color:gray">2</span><br />10<br />-<br />- </td> <td style="background:#9bff99; width:2em;">67<br /><b><a href="/wiki/Holmium" title="Holmium">Ho</a></b><br /><span style="color:gray">2</span><br />11<br />-<br />- </td> <td style="background:#9bff99; width:2em;">68<br /><b><a href="/wiki/Erbium" title="Erbium">Er</a></b><br /><span style="color:gray">2</span><br />12<br />-<br />- </td> <td style="background:#9bff99; width:2em;">69<br /><b><a href="/wiki/Thulium" title="Thulium">Tm</a></b><br /><span style="color:gray">2</span><br />13<br />-<br />- </td> <td style="background:#9bff99; width:2em;">70<br /><b><a href="/wiki/Ytterbium" title="Ytterbium">Yb</a></b><br /><span style="color:gray">2<br />14</span><br />-<br />- </td> <td style="background:#99ccff;">71<br /><b><a href="/wiki/Lutetium" title="Lutetium">Lu</a></b><br /><span style="color:gray">2<br />14</span><br />1<br />- </td> <td style="background:#99ccff;">72<br /><b><a href="/wiki/Hafnium" title="Hafnium">Hf</a></b><br /><span style="color:gray">2<br />14</span><br />2<br />- </td> <td style="background:#99ccff;">73<br /><b><a href="/wiki/Tantalum" title="Tantalum">Ta</a></b><br /><span style="color:gray">2<br />14</span><br />3<br />- </td> <td style="background:#99ccff;">74<br /><b><a href="/wiki/Tungsten" title="Tungsten">W</a></b><br /><span style="color:gray">2<br />14</span><br />4<br />- </td> <td style="background:#99ccff;">75<br /><b><a href="/wiki/Rhenium" title="Rhenium">Re</a></b><br /><span style="color:gray">2<br />14</span><br />5<br />- </td> <td style="background:#99ccff;">76<br /><b><a href="/wiki/Osmium" title="Osmium">Os</a></b><br /><span style="color:gray">2<br />14</span><br />6<br />- </td> <td style="background:#99ccff;">77<br /><b><a href="/wiki/Iridium" title="Iridium">Ir</a></b><br /><span style="color:gray">2<br />14</span><br />7<br />- </td> <td style="background:#99ccff;">78<br /><b><a href="/wiki/Platinum" title="Platinum">Pt</a></b><br />1<br /><span style="color:gray">14</span><br />9<br />- </td> <td style="background:#99ccff;">79<br /><b><a href="/wiki/Gold" title="Gold">Au</a></b><br />1<br /><span style="color:gray">14<br />10</span><br />- </td> <td style="background:#99ccff;">80<br /><b><a href="/wiki/Mercury_(element)" title="Mercury (element)">Hg</a></b><br /><span style="color:gray">2<br />14<br />10</span><br />- </td> <td style="background:#fdff8c;">81<br /><b><a href="/wiki/Thallium" title="Thallium">Tl</a></b><br /><span style="color:gray">2<br />14<br />10</span><br />1 </td> <td style="background:#fdff8c;">82<br /><b><a href="/wiki/Lead" title="Lead">Pb</a></b><br /><span style="color:gray">2<br />14<br />10</span><br />2 </td> <td style="background:#fdff8c;">83<br /><b><a href="/wiki/Bismuth" title="Bismuth">Bi</a></b><br /><span style="color:gray">2<br />14<br />10</span><br />3 </td> <td style="background:#fdff8c;">84<br /><b><a href="/wiki/Polonium" title="Polonium">Po</a></b><br /><span style="color:gray">2<br />14<br />10</span><br />4 </td> <td style="background:#fdff8c;">85<br /><b><a href="/wiki/Astatine" title="Astatine">At</a></b><br /><span style="color:gray">2<br />14<br />10</span><br />5 </td> <td style="background:#fdff8c;">86<br /><b><a href="/wiki/Radon" title="Radon">Rn</a></b><br /><span style="color:gray">2<br />14<br />10<br />6</span> </td></tr> <tr style="border-bottom:2px solid #f8f8f8;"> <td style="background:#e8e8e8; vertical-align:bottom"><small style="color:gray">[Rn]</small><br />7s:<br />5f:<br />6d:<br />7p: </td> <td style="background:#ff9999;">87<br /><b><a href="/wiki/Francium" title="Francium">Fr</a></b><br />1<br />-<br />-<br />- </td> <td style="background:#ff9999;">88<br /><b><a href="/wiki/Radium" title="Radium">Ra</a></b><br /><span style="color:gray">2</span><br />-<br />-<br />- </td> <td style="background:#9bff99;">89<br /><b><a href="/wiki/Actinium" title="Actinium">Ac</a></b><br /><span style="color:gray">2</span><br />-<br />1<br />- </td> <td style="background:#9bff99;">90<br /><b><a href="/wiki/Thorium" title="Thorium">Th</a></b><br /><span style="color:gray">2</span><br />-<br />2<br />- </td> <td style="background:#9bff99;">91<br /><b><a href="/wiki/Protactinium" title="Protactinium">Pa</a></b><br /><span style="color:gray">2</span><br />2<br />1<br />- </td> <td style="background:#9bff99;">92<br /><b><a href="/wiki/Uranium" title="Uranium">U</a></b><br /><span style="color:gray">2</span><br />3<br />1<br />- </td> <td style="background:#9bff99;">93<br /><b><a href="/wiki/Neptunium" title="Neptunium">Np</a></b><br /><span style="color:gray">2</span><br />4<br />1<br />- </td> <td style="background:#9bff99;">94<br /><b><a href="/wiki/Plutonium" title="Plutonium">Pu</a></b><br /><span style="color:gray">2</span><br />6<br />-<br />- </td> <td style="background:#9bff99;">95<br /><b><a href="/wiki/Americium" title="Americium">Am</a></b><br /><span style="color:gray">2</span><br />7<br />-<br />- </td> <td style="background:#9bff99;">96<br /><b><a href="/wiki/Curium" title="Curium">Cm</a></b><br /><span style="color:gray">2</span><br />7<br />1<br />- </td> <td style="background:#9bff99;">97<br /><b><a href="/wiki/Berkelium" title="Berkelium">Bk</a></b><br /><span style="color:gray">2</span><br />9<br />-<br />- </td> <td style="background:#9bff99;">98<br /><b><a href="/wiki/Californium" title="Californium">Cf</a></b><br /><span style="color:gray">2</span><br />10<br />-<br />- </td> <td style="background:#9bff99;">99<br /><b><a href="/wiki/Einsteinium" title="Einsteinium">Es</a></b><br /><span style="color:gray">2</span><br />11<br />-<br />- </td> <td style="background:#9bff99;">100<br /><b><a href="/wiki/Fermium" title="Fermium">Fm</a></b><br /><span style="color:gray">2</span><br />12<br />-<br />- </td> <td style="background:#9bff99;">101<br /><b><a href="/wiki/Mendelevium" title="Mendelevium">Md</a></b><br /><span style="color:gray">2</span><br />13<br />-<br />- </td> <td style="background:#9bff99;">102<br /><b><a href="/wiki/Nobelium" title="Nobelium">No</a></b><br /><span style="color:gray">2<br />14</span><br />-<br />- </td> <td style="background:#99ccff;">103<br /><b><a href="/wiki/Lawrencium" title="Lawrencium">Lr</a></b><br /><span style="color:gray">2<br />14</span><br />-<br />1 </td> <td style="background:#99ccff;">104<br /><b><a href="/wiki/Rutherfordium" title="Rutherfordium">Rf</a></b><br /><span style="color:gray">2<br />14</span><br />2<br />- </td> <td style="background:#99ccff;">105<br /><b><a href="/wiki/Dubnium" title="Dubnium">Db</a></b><br /><span style="color:gray">2<br />14</span><br />3<br />- </td> <td style="background:#99ccff;">106<br /><b><a href="/wiki/Seaborgium" title="Seaborgium">Sg</a></b><br /><span style="color:gray">2<br />14</span><br />4<br />- </td> <td style="background:#99ccff;">107<br /><b><a href="/wiki/Bohrium" title="Bohrium">Bh</a></b><br /><span style="color:gray">2<br />14</span><br />5<br />- </td> <td style="background:#99ccff;">108<br /><b><a href="/wiki/Hassium" title="Hassium">Hs</a></b><br /><span style="color:gray">2<br />14</span><br />6<br />- </td> <td style="background:#99ccff;">109<br /><b><a href="/wiki/Meitnerium" title="Meitnerium">Mt</a></b><br /><span style="color:gray">2<br />14</span><br />7<br />- </td> <td style="background:#99ccff;">110<br /><b><a href="/wiki/Darmstadtium" title="Darmstadtium">Ds</a></b><br /><span style="color:gray">2<br />14</span><br />8<br />- </td> <td style="background:#99ccff;">111<br /><b><a href="/wiki/Roentgenium" title="Roentgenium">Rg</a></b><br /><span style="color:gray">2<br />14</span><br />9<br />- </td> <td style="background:#99ccff;">112<br /><b><a href="/wiki/Copernicium" title="Copernicium">Cn</a></b><br /><span style="color:gray">2<br />14<br />10</span><br />- </td> <td style="background:#fdff8c;">113<br /><b><a href="/wiki/Nihonium" title="Nihonium">Nh</a></b><br /><span style="color:gray">2<br />14<br />10</span><br />1 </td> <td style="background:#fdff8c;">114<br /><b><a href="/wiki/Flerovium" title="Flerovium">Fl</a></b><br /><span style="color:gray">2<br />14<br />10</span><br />2 </td> <td style="background:#fdff8c;">115<br /><b><a href="/wiki/Moscovium" title="Moscovium">Mc</a></b><br /><span style="color:gray">2<br />14<br />10</span><br />3 </td> <td style="background:#fdff8c;">116<br /><b><a href="/wiki/Livermorium" title="Livermorium">Lv</a></b><br /><span style="color:gray">2<br />14<br />10</span><br />4 </td> <td style="background:#fdff8c;">117<br /><b><a href="/wiki/Tennessine" title="Tennessine">Ts</a></b><br /><span style="color:gray">2<br />14<br />10</span><br />5 </td> <td style="background:#fdff8c;">118<br /><b><a href="/wiki/Oganesson" title="Oganesson">Og</a></b><br /><span style="color:gray">2<br />14<br />10<br />6</span> </td></tr> <tr> <td colspan="33"> <div role="presentation" id="periodic-table-legend" style="border: 1px solid #a2a9b1; width:100%; line-height:120%; text-align:center; vertical-align:top; background:#f8f8f8; margin:0;"><div style="padding:0.3em;"> <table style="width:100%; line-height:1.2em; table-layout:fixed; overflow:hidden; text-align:center;"> <tbody><tr> <td style="padding:0 1px; background:#ff9999;"><a href="/wiki/S-block" class="mw-redirect" title="S-block">s-block</a> </td> <td style="padding:0 1px; background:#9bff99;"><a href="/wiki/F-block" class="mw-redirect" title="F-block">f-block</a> </td> <td style="padding:0 1px; background:#99ccff;"><a href="/wiki/D-block" class="mw-redirect" title="D-block">d-block</a> </td> <td style="padding:0 1px; background:#fdff8c;"><a href="/wiki/P-block" class="mw-redirect" title="P-block">p-block</a> </td></tr></tbody></table> </div> </div> </td></tr></tbody></table> <div class="mw-heading mw-heading2"><h2 id="Variations">Variations</h2></div> <div class="mw-heading mw-heading3"><h3 id="Period_1">Period 1</h3></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Period_1_element" title="Period 1 element">Period 1 element</a></div> <p>Although the modern periodic table is standard today, the placement of the period 1 elements hydrogen and helium remains an open issue under discussion, and some variation can be found.<sup id="cite_ref-KW_64-3" class="reference"><a href="#cite_note-KW-64"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Lemonick_91-0" class="reference"><a href="#cite_note-Lemonick-91"><span class="cite-bracket">[</span>81<span class="cite-bracket">]</span></a></sup> Following their respective s<sup>1</sup> and s<sup>2</sup> electron configurations, hydrogen would be placed in group 1, and helium would be placed in group 2.<sup id="cite_ref-KW_64-4" class="reference"><a href="#cite_note-KW-64"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup> The group 1 placement of hydrogen is common, but helium is almost always placed in group 18 with the other noble gases.<sup id="cite_ref-IUPAC-redbook_7-6" class="reference"><a href="#cite_note-IUPAC-redbook-7"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> The debate has to do with conflicting understandings of the extent to which chemical or electronic properties should decide periodic table placement.<sup id="cite_ref-Lemonick_91-1" class="reference"><a href="#cite_note-Lemonick-91"><span class="cite-bracket">[</span>81<span class="cite-bracket">]</span></a></sup> </p><p>Like the group 1 metals, hydrogen has one electron in its outermost shell<sup id="cite_ref-Gray12_92-0" class="reference"><a href="#cite_note-Gray12-92"><span class="cite-bracket">[</span>82<span class="cite-bracket">]</span></a></sup> and typically loses its only electron in chemical reactions.<sup id="cite_ref-Vlasov_93-0" class="reference"><a href="#cite_note-Vlasov-93"><span class="cite-bracket">[</span>83<span class="cite-bracket">]</span></a></sup> Hydrogen has some metal-like chemical properties, being able to displace some metals from their <a href="/wiki/Salt_(chemistry)" title="Salt (chemistry)">salts</a>.<sup id="cite_ref-Vlasov_93-1" class="reference"><a href="#cite_note-Vlasov-93"><span class="cite-bracket">[</span>83<span class="cite-bracket">]</span></a></sup> But it forms a diatomic nonmetallic gas at standard conditions, unlike the alkali metals which are reactive solid metals. This and hydrogen's formation of <a href="/wiki/Hydride" title="Hydride">hydrides</a>, in which it gains an electron, brings it close to the properties of the <a href="/wiki/Halogen" title="Halogen">halogens</a> which do the same<sup id="cite_ref-Vlasov_93-2" class="reference"><a href="#cite_note-Vlasov-93"><span class="cite-bracket">[</span>83<span class="cite-bracket">]</span></a></sup> (though it is rarer for hydrogen to form H<sup>−</sup> than H<sup>+</sup>).<sup id="cite_ref-raynercanham_94-0" class="reference"><a href="#cite_note-raynercanham-94"><span class="cite-bracket">[</span>84<span class="cite-bracket">]</span></a></sup> Moreover, the lightest two halogens (<a href="/wiki/Fluorine" title="Fluorine">fluorine</a> and <a href="/wiki/Chlorine" title="Chlorine">chlorine</a>) are gaseous like hydrogen at standard conditions.<sup id="cite_ref-Vlasov_93-3" class="reference"><a href="#cite_note-Vlasov-93"><span class="cite-bracket">[</span>83<span class="cite-bracket">]</span></a></sup> Some properties of hydrogen are not a good fit for either group: hydrogen is neither highly oxidizing nor highly reducing and is not reactive with water.<sup id="cite_ref-raynercanham_94-1" class="reference"><a href="#cite_note-raynercanham-94"><span class="cite-bracket">[</span>84<span class="cite-bracket">]</span></a></sup> Hydrogen thus has properties corresponding to both those of the alkali metals and the halogens, but matches neither group perfectly, and is thus difficult to place by its chemistry.<sup id="cite_ref-Vlasov_93-4" class="reference"><a href="#cite_note-Vlasov-93"><span class="cite-bracket">[</span>83<span class="cite-bracket">]</span></a></sup> Therefore, while the electronic placement of hydrogen in group 1 predominates, some rarer arrangements show either hydrogen in group 17,<sup id="cite_ref-95" class="reference"><a href="#cite_note-95"><span class="cite-bracket">[</span>85<span class="cite-bracket">]</span></a></sup> duplicate hydrogen in both groups 1 and 17,<sup id="cite_ref-96" class="reference"><a href="#cite_note-96"><span class="cite-bracket">[</span>86<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Kaesz_97-0" class="reference"><a href="#cite_note-Kaesz-97"><span class="cite-bracket">[</span>87<span class="cite-bracket">]</span></a></sup> or float it separately from all groups.<sup id="cite_ref-Kaesz_97-1" class="reference"><a href="#cite_note-Kaesz-97"><span class="cite-bracket">[</span>87<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-GE_98-0" class="reference"><a href="#cite_note-GE-98"><span class="cite-bracket">[</span>88<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-KW_64-5" class="reference"><a href="#cite_note-KW-64"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup> This last option has nonetheless been criticized by the chemist and philosopher of science <a href="/wiki/Eric_Scerri" title="Eric Scerri">Eric Scerri</a> on the grounds that it appears to imply that hydrogen is above the periodic law altogether, unlike all the other elements.<sup id="cite_ref-99" class="reference"><a href="#cite_note-99"><span class="cite-bracket">[</span>89<span class="cite-bracket">]</span></a></sup> </p><p>Helium is the only element that routinely occupies a position in the periodic table that is not consistent with its electronic structure. It has two electrons in its outermost shell, whereas the other noble gases have eight; and it is an s-block element, whereas all other noble gases are p-block elements. However it is unreactive at standard conditions, and has a full outer shell: these properties are like the noble gases in group 18, but not at all like the reactive alkaline earth metals of group 2. For these reasons helium is nearly universally placed in group 18<sup id="cite_ref-IUPAC-redbook_7-7" class="reference"><a href="#cite_note-IUPAC-redbook-7"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> which its properties best match;<sup id="cite_ref-KW_64-6" class="reference"><a href="#cite_note-KW-64"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup> a proposal to move helium to group 2 was rejected by IUPAC in 1988 for these reasons.<sup id="cite_ref-Fluck_27-3" class="reference"><a href="#cite_note-Fluck-27"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> Nonetheless, helium is still occasionally placed in group 2 today,<sup id="cite_ref-shattered_100-0" class="reference"><a href="#cite_note-shattered-100"><span class="cite-bracket">[</span>90<span class="cite-bracket">]</span></a></sup> and some of its physical and chemical properties are closer to the group 2 elements and support the electronic placement.<sup id="cite_ref-Gray12_92-1" class="reference"><a href="#cite_note-Gray12-92"><span class="cite-bracket">[</span>82<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-KW_64-7" class="reference"><a href="#cite_note-KW-64"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup> Solid helium crystallises in a <a href="/wiki/Hexagonal_close-packed" class="mw-redirect" title="Hexagonal close-packed">hexagonal close-packed</a> structure, which matches beryllium and magnesium in group 2, but not the other noble gases in group 18.<sup id="cite_ref-Kurushkin_101-0" class="reference"><a href="#cite_note-Kurushkin-101"><span class="cite-bracket">[</span>91<span class="cite-bracket">]</span></a></sup> Recent theoretical developments in noble gas chemistry, in which helium is expected to show slightly less inertness than neon and to form (HeO)(LiF)<sub>2</sub> with a structure similar to the analogous beryllium compound (but with no expected neon analogue), have resulted in more chemists advocating a placement of helium in group 2. This relates to the electronic argument, as the reason for neon's greater inertness is repulsion from its filled p-shell that helium lacks, though realistically it is unlikely that helium-containing molecules will be stable outside extreme low-temperature conditions (around 10 <a href="/wiki/Kelvin" title="Kelvin">K</a>).<sup id="cite_ref-PTSS_102-0" class="reference"><a href="#cite_note-PTSS-102"><span class="cite-bracket">[</span>92<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-grochala_103-0" class="reference"><a href="#cite_note-grochala-103"><span class="cite-bracket">[</span>93<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-104" class="reference"><a href="#cite_note-104"><span class="cite-bracket">[</span>94<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-105" class="reference"><a href="#cite_note-105"><span class="cite-bracket">[</span>95<span class="cite-bracket">]</span></a></sup> </p><p>The <a href="/wiki/Nonmetal_(chemistry)#First_row_anomaly" class="mw-redirect" title="Nonmetal (chemistry)">first-row anomaly</a> in the periodic table has additionally been cited to support moving helium to group 2. It arises because the first orbital of any type is unusually small, since unlike its higher analogues, it does not experience interelectronic repulsion from a smaller orbital of the same type. This makes the first row of elements in each block unusually small, and such elements tend to exhibit characteristic kinds of anomalies for their group. Some chemists arguing for the repositioning of helium have pointed out that helium exhibits these anomalies if it is placed in group 2, but not if it is placed in group 18: on the other hand, neon, which would be the first group 18 element if helium was removed from that spot, does exhibit those anomalies.<sup id="cite_ref-PTSS_102-1" class="reference"><a href="#cite_note-PTSS-102"><span class="cite-bracket">[</span>92<span class="cite-bracket">]</span></a></sup> The relationship between helium and beryllium is then argued to resemble that between hydrogen and lithium, a placement which is much more commonly accepted.<sup id="cite_ref-grochala_103-1" class="reference"><a href="#cite_note-grochala-103"><span class="cite-bracket">[</span>93<span class="cite-bracket">]</span></a></sup> For example, because of this trend in the sizes of orbitals, a large difference in atomic radii between the first and second members of each main group is seen in groups 1 and 13–17: it exists between neon and argon, and between helium and beryllium, but not between helium and neon. This similarly affects the noble gases' boiling points and solubilities in water, where helium is too close to neon, and the large difference characteristic between the first two elements of a group appears only between neon and argon. Moving helium to group 2 makes this trend consistent in groups 2 and 18 as well, by making helium the first group 2 element and neon the first group 18 element: both exhibit the characteristic properties of a kainosymmetric first element of a group.<sup id="cite_ref-SB23_106-0" class="reference"><a href="#cite_note-SB23-106"><span class="cite-bracket">[</span>96<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-107" class="reference"><a href="#cite_note-107"><span class="cite-bracket">[</span>97<span class="cite-bracket">]</span></a></sup> The group 18 placement of helium nonetheless remains near-universal due to its extreme inertness.<sup id="cite_ref-108" class="reference"><a href="#cite_note-108"><span class="cite-bracket">[</span>98<span class="cite-bracket">]</span></a></sup> Additionally, tables that float both hydrogen and helium outside all groups may rarely be encountered.<sup id="cite_ref-GE_98-1" class="reference"><a href="#cite_note-GE-98"><span class="cite-bracket">[</span>88<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-KW_64-8" class="reference"><a href="#cite_note-KW-64"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-jensenlaw_66-16" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Group_3">Group 3</h3></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Group_3_element#Composition" title="Group 3 element">Group 3 element § Composition</a></div> <div role="navigation" aria-labelledby="micro-periodic-table-title" aria-describedby="micro-periodic-table-caption" style="float:right; background:#f8f8f8; padding:0.3em; border:1px solid #a9a9a9; margin:0 0 0.25em 0.5em; text-align:center;;"> <div id="micro-periodic-table-title" style="background:#d8d8d8; padding:0.15em 0.3em; font-size:90%; line-height:110%; font-weight:bold;">Group 3: Sc, Y, Lu, Lr <span typeof="mw:File"><a href="/wiki/File:Yes_check.svg" class="mw-file-description" title="Correct"><img alt="Correct" src="//upload.wikimedia.org/wikipedia/en/thumb/f/fb/Yes_check.svg/15px-Yes_check.svg.png" decoding="async" width="15" height="15" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/f/fb/Yes_check.svg/23px-Yes_check.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/f/fb/Yes_check.svg/30px-Yes_check.svg.png 2x" data-file-width="600" data-file-height="600" /></a></span></div> <div style="margin: 0.15em 0; display:table-row;"><div style="background-color:transparent; color:inherit; margin:0; padding:0; text-align:center; border:none;"> <table style="empty-cells:hidden; border:none; padding:0; border-spacing:1px; border-collapse:separate; margin:0;"> <tbody><tr> <td style="border:none;padding:0;"><a href="/wiki/Hydrogen" title="Hydrogen"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Hydrogen</span></a> </td> <td colspan="30" style="border:none;padding:0;"> </td> <td style="border:none;padding:0;"><a href="/wiki/Helium" title="Helium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Helium</span></a> </td></tr> <tr> <td style="border:none;padding:0;"><a href="/wiki/Lithium" title="Lithium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Lithium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Beryllium" title="Beryllium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Beryllium</span></a> </td> <td colspan="24" style="border:none;padding:0;"> </td> <td style="border:none;padding:0;"><a href="/wiki/Boron" title="Boron"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Boron</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Carbon" title="Carbon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Carbon</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Nitrogen" title="Nitrogen"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Nitrogen</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Oxygen" title="Oxygen"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Oxygen</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Fluorine" title="Fluorine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Fluorine</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Neon" title="Neon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Neon</span></a> </td></tr> <tr> <td style="border:none;padding:0;"><a href="/wiki/Sodium" title="Sodium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Sodium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Magnesium" title="Magnesium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Magnesium</span></a> </td> <td colspan="24" style="border:none;padding:0;"> </td> <td style="border:none;padding:0;"><a href="/wiki/Aluminium" title="Aluminium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Aluminium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Silicon" title="Silicon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Silicon</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Phosphorus" title="Phosphorus"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Phosphorus</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Sulfur" title="Sulfur"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Sulfur</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Chlorine" title="Chlorine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Chlorine</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Argon" title="Argon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Argon</span></a> </td></tr> <tr> <td style="border:none;padding:0;"><a href="/wiki/Potassium" title="Potassium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Potassium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Calcium" title="Calcium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Calcium</span></a> </td> <td colspan="14" style="border:none;padding:0;"> </td> <td style="border:none;padding:0;"><a href="/wiki/Scandium" title="Scandium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff; border:1px solid black; box-sizing: border-box;;">Scandium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Titanium" title="Titanium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Titanium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Vanadium" title="Vanadium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Vanadium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Chromium" title="Chromium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Chromium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Manganese" title="Manganese"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Manganese</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Iron" title="Iron"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Iron</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Cobalt" title="Cobalt"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Cobalt</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Nickel" title="Nickel"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Nickel</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Copper" title="Copper"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Copper</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Zinc" title="Zinc"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Zinc</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Gallium" title="Gallium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Gallium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Germanium" title="Germanium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Germanium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Arsenic" title="Arsenic"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Arsenic</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Selenium" title="Selenium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Selenium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Bromine" title="Bromine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Bromine</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Krypton" title="Krypton"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Krypton</span></a> </td></tr> <tr> <td style="border:none;padding:0;"><a href="/wiki/Rubidium" title="Rubidium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Rubidium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Strontium" title="Strontium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Strontium</span></a> </td> <td style="border:none;padding:0;; width:0;"> </td> <td colspan="13" style="border:none;padding:0;"> </td> <td style="border:none;padding:0;"><a href="/wiki/Yttrium" title="Yttrium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff; border:1px solid black; box-sizing: border-box;;">Yttrium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Zirconium" title="Zirconium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Zirconium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Niobium" title="Niobium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Niobium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Molybdenum" title="Molybdenum"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Molybdenum</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Technetium" title="Technetium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Technetium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Ruthenium" title="Ruthenium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Ruthenium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Rhodium" title="Rhodium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Rhodium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Palladium" title="Palladium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Palladium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Silver" title="Silver"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Silver</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Cadmium" title="Cadmium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Cadmium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Indium" title="Indium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Indium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Tin" title="Tin"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Tin</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Antimony" title="Antimony"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Antimony</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Tellurium" title="Tellurium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Tellurium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Iodine" title="Iodine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Iodine</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Xenon" title="Xenon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Xenon</span></a> </td></tr> <tr style="border:none;padding:0;"> <td style="border:none;padding:0;"><a href="/wiki/Caesium" title="Caesium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Caesium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Barium" title="Barium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Barium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Lanthanum" title="Lanthanum"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Lanthanum</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Cerium" title="Cerium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Cerium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Praseodymium" title="Praseodymium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Praseodymium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Neodymium" title="Neodymium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Neodymium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Promethium" title="Promethium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Promethium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Samarium" title="Samarium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Samarium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Europium" title="Europium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Europium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Gadolinium" title="Gadolinium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Gadolinium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Terbium" title="Terbium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Terbium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Dysprosium" title="Dysprosium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Dysprosium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Holmium" title="Holmium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Holmium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Erbium" title="Erbium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Erbium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Thulium" title="Thulium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Thulium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Ytterbium" title="Ytterbium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Ytterbium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Lutetium" title="Lutetium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff; border:1px solid black; box-sizing: border-box;;">Lutetium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Hafnium" title="Hafnium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Hafnium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Tantalum" title="Tantalum"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Tantalum</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Tungsten" title="Tungsten"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Tungsten</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Rhenium" title="Rhenium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Rhenium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Osmium" title="Osmium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Osmium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Iridium" title="Iridium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Iridium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Platinum" title="Platinum"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Platinum</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Gold" title="Gold"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Gold</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Mercury_(element)" title="Mercury (element)"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Mercury (element)</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Thallium" title="Thallium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Thallium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Lead" title="Lead"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Lead</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Bismuth" title="Bismuth"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Bismuth</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Polonium" title="Polonium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Polonium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Astatine" title="Astatine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Astatine</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Radon" title="Radon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Radon</span></a> </td></tr> <tr> <td style="border:none;padding:0;"><a href="/wiki/Francium" title="Francium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Francium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Radium" title="Radium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Radium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Actinium" title="Actinium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Actinium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Thorium" title="Thorium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Thorium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Protactinium" title="Protactinium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Protactinium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Uranium" title="Uranium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Uranium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Neptunium" title="Neptunium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Neptunium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Plutonium" title="Plutonium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Plutonium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Americium" title="Americium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Americium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Curium" title="Curium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Curium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Berkelium" title="Berkelium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Berkelium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Californium" title="Californium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Californium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Einsteinium" title="Einsteinium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Einsteinium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Fermium" title="Fermium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Fermium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Mendelevium" title="Mendelevium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Mendelevium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Nobelium" title="Nobelium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Nobelium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Lawrencium" title="Lawrencium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff; border:1px solid black; box-sizing: border-box;;">Lawrencium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Rutherfordium" title="Rutherfordium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Rutherfordium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Dubnium" title="Dubnium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Dubnium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Seaborgium" title="Seaborgium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Seaborgium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Bohrium" title="Bohrium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Bohrium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Hassium" title="Hassium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Hassium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Meitnerium" title="Meitnerium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Meitnerium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Darmstadtium" title="Darmstadtium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Darmstadtium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Roentgenium" title="Roentgenium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Roentgenium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Copernicium" title="Copernicium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Copernicium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Nihonium" title="Nihonium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Nihonium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Flerovium" title="Flerovium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Flerovium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Moscovium" title="Moscovium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Moscovium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Livermorium" title="Livermorium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Livermorium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Tennessine" title="Tennessine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Tennessine</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Oganesson" title="Oganesson"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Oganesson</span></a> </td></tr></tbody></table> </div></div> <div id="micro-periodic-table-caption" style="font-size:85%; line-height:100%; display:table-caption; caption-side:bottom;">Correct depiction of Group 3</div> </div> <div role="navigation" aria-labelledby="micro-periodic-table-title" aria-describedby="micro-periodic-table-caption" style="float:right; background:#f8f8f8; padding:0.3em; border:1px solid #a9a9a9; margin:0 0 0.25em 0.5em; text-align:center;;"> <div id="micro-periodic-table-title" style="background:#d8d8d8; padding:0.15em 0.3em; font-size:90%; line-height:110%; font-weight:bold;">Group 3: Sc, Y, La, Ac <span typeof="mw:File"><a href="/wiki/File:X_mark.svg" class="mw-file-description" title="Incorrect"><img alt="Incorrect" src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a2/X_mark.svg/15px-X_mark.svg.png" decoding="async" width="15" height="17" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a2/X_mark.svg/23px-X_mark.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a2/X_mark.svg/30px-X_mark.svg.png 2x" data-file-width="525" data-file-height="600" /></a></span></div> <div style="margin: 0.15em 0; display:table-row;"><div style="background-color:transparent; margin:0; padding:0; text-align:center; border:none;"> <table style="empty-cells:hidden; border:none; padding:0; border-spacing:1px; border-collapse:separate; margin:0;"> <tbody><tr> <td style="border:none;padding:0;"><a href="/wiki/Hydrogen" title="Hydrogen"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Hydrogen</span></a> </td> <td colspan="30" style="border:none;padding:0;"> </td> <td style="border:none;padding:0;"><a href="/wiki/Helium" title="Helium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Helium</span></a> </td></tr> <tr> <td style="border:none;padding:0;"><a href="/wiki/Lithium" title="Lithium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Lithium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Beryllium" title="Beryllium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Beryllium</span></a> </td> <td colspan="24" style="border:none;padding:0;"> </td> <td style="border:none;padding:0;"><a href="/wiki/Boron" title="Boron"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Boron</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Carbon" title="Carbon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Carbon</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Nitrogen" title="Nitrogen"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Nitrogen</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Oxygen" title="Oxygen"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Oxygen</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Fluorine" title="Fluorine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Fluorine</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Neon" title="Neon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Neon</span></a> </td></tr> <tr> <td style="border:none;padding:0;"><a href="/wiki/Sodium" title="Sodium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Sodium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Magnesium" title="Magnesium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Magnesium</span></a> </td> <td colspan="24" style="border:none;padding:0;"> </td> <td style="border:none;padding:0;"><a href="/wiki/Aluminium" title="Aluminium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Aluminium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Silicon" title="Silicon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Silicon</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Phosphorus" title="Phosphorus"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Phosphorus</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Sulfur" title="Sulfur"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Sulfur</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Chlorine" title="Chlorine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Chlorine</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Argon" title="Argon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Argon</span></a> </td></tr> <tr> <td style="border:none;padding:0;"><a href="/wiki/Potassium" title="Potassium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Potassium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Calcium" title="Calcium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Calcium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Scandium" title="Scandium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff; border:1px solid black; box-sizing: border-box;;">Scandium</span></a> </td> <td colspan="14" style="border:none;padding:0;"> </td> <td style="border:none;padding:0;"><a href="/wiki/Titanium" title="Titanium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Titanium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Vanadium" title="Vanadium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Vanadium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Chromium" title="Chromium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Chromium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Manganese" title="Manganese"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Manganese</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Iron" title="Iron"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Iron</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Cobalt" title="Cobalt"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Cobalt</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Nickel" title="Nickel"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Nickel</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Copper" title="Copper"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Copper</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Zinc" title="Zinc"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Zinc</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Gallium" title="Gallium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Gallium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Germanium" title="Germanium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Germanium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Arsenic" title="Arsenic"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Arsenic</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Selenium" title="Selenium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Selenium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Bromine" title="Bromine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Bromine</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Krypton" title="Krypton"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Krypton</span></a> </td></tr> <tr> <td style="border:none;padding:0;"><a href="/wiki/Rubidium" title="Rubidium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Rubidium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Strontium" title="Strontium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Strontium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Yttrium" title="Yttrium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff; border:1px solid black; box-sizing: border-box;;">Yttrium</span></a> </td> <td style="border:none;padding:0;; width:0;"> </td> <td colspan="13" style="border:none;padding:0;"> </td> <td style="border:none;padding:0;"><a href="/wiki/Zirconium" title="Zirconium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Zirconium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Niobium" title="Niobium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Niobium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Molybdenum" title="Molybdenum"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Molybdenum</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Technetium" title="Technetium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Technetium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Ruthenium" title="Ruthenium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Ruthenium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Rhodium" title="Rhodium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Rhodium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Palladium" title="Palladium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Palladium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Silver" title="Silver"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Silver</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Cadmium" title="Cadmium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Cadmium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Indium" title="Indium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Indium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Tin" title="Tin"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Tin</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Antimony" title="Antimony"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Antimony</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Tellurium" title="Tellurium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Tellurium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Iodine" title="Iodine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Iodine</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Xenon" title="Xenon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Xenon</span></a> </td></tr> <tr style="border:none;padding:0;"> <td style="border:none;padding:0;"><a href="/wiki/Caesium" title="Caesium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Caesium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Barium" title="Barium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Barium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Lanthanum" title="Lanthanum"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff; border:1px solid black; box-sizing: border-box;;">Lanthanum</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Cerium" title="Cerium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Cerium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Praseodymium" title="Praseodymium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Praseodymium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Neodymium" title="Neodymium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Neodymium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Promethium" title="Promethium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Promethium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Samarium" title="Samarium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Samarium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Europium" title="Europium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Europium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Gadolinium" title="Gadolinium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Gadolinium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Terbium" title="Terbium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Terbium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Dysprosium" title="Dysprosium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Dysprosium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Holmium" title="Holmium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Holmium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Erbium" title="Erbium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Erbium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Thulium" title="Thulium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Thulium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Ytterbium" title="Ytterbium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Ytterbium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Lutetium" title="Lutetium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Lutetium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Hafnium" title="Hafnium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Hafnium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Tantalum" title="Tantalum"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Tantalum</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Tungsten" title="Tungsten"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Tungsten</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Rhenium" title="Rhenium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Rhenium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Osmium" title="Osmium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Osmium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Iridium" title="Iridium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Iridium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Platinum" title="Platinum"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Platinum</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Gold" title="Gold"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Gold</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Mercury_(element)" title="Mercury (element)"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Mercury (element)</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Thallium" title="Thallium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Thallium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Lead" title="Lead"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Lead</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Bismuth" title="Bismuth"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Bismuth</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Polonium" title="Polonium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Polonium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Astatine" title="Astatine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Astatine</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Radon" title="Radon"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Radon</span></a> </td></tr> <tr> <td style="border:none;padding:0;"><a href="/wiki/Francium" title="Francium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Francium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Radium" title="Radium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#ff9999;">Radium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Actinium" title="Actinium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff; border:1px solid black; box-sizing: border-box;;">Actinium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Thorium" title="Thorium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Thorium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Protactinium" title="Protactinium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Protactinium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Uranium" title="Uranium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Uranium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Neptunium" title="Neptunium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Neptunium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Plutonium" title="Plutonium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Plutonium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Americium" title="Americium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Americium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Curium" title="Curium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Curium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Berkelium" title="Berkelium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Berkelium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Californium" title="Californium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Californium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Einsteinium" title="Einsteinium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Einsteinium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Fermium" title="Fermium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Fermium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Mendelevium" title="Mendelevium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Mendelevium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Nobelium" title="Nobelium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Nobelium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Lawrencium" title="Lawrencium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#9bff99;">Lawrencium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Rutherfordium" title="Rutherfordium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Rutherfordium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Dubnium" title="Dubnium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Dubnium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Seaborgium" title="Seaborgium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Seaborgium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Bohrium" title="Bohrium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Bohrium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Hassium" title="Hassium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Hassium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Meitnerium" title="Meitnerium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Meitnerium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Darmstadtium" title="Darmstadtium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Darmstadtium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Roentgenium" title="Roentgenium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Roentgenium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Copernicium" title="Copernicium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#99ccff;">Copernicium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Nihonium" title="Nihonium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Nihonium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Flerovium" title="Flerovium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Flerovium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Moscovium" title="Moscovium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Moscovium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Livermorium" title="Livermorium"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Livermorium</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Tennessine" title="Tennessine"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Tennessine</span></a> </td> <td style="border:none;padding:0;"><a href="/wiki/Oganesson" title="Oganesson"><span style="display:block;width:6px;height:8px;overflow:hidden;padding:0;color:transparent;background-color:#fdff8c;">Oganesson</span></a> </td></tr></tbody></table> </div></div> <div id="micro-periodic-table-caption" style="font-size:85%; line-height:100%; display:table-caption; caption-side:bottom;">Incorrect depiction of Group 3</div> </div> <p>In many periodic tables, the f-block is shifted one element to the right, so that lanthanum and actinium become d-block elements in group 3, and Ce–Lu and Th–Lr form the f-block. Thus the d-block is split into two very uneven portions. This is a holdover from early mistaken measurements of electron configurations; modern measurements are more consistent with the form with lutetium and lawrencium in group 3, and with La–Yb and Ac–No as the f-block.<sup id="cite_ref-Jensen1982_29-1" class="reference"><a href="#cite_note-Jensen1982-29"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-wulfsberg53_109-0" class="reference"><a href="#cite_note-wulfsberg53-109"><span class="cite-bracket">[</span>99<span class="cite-bracket">]</span></a></sup> </p><p>The 4f shell is completely filled at ytterbium, and for that reason <a href="/wiki/Lev_Landau" title="Lev Landau">Lev Landau</a> and <a href="/wiki/Evgeny_Lifshitz" title="Evgeny Lifshitz">Evgeny Lifshitz</a> in 1948 considered it incorrect to group lutetium as an f-block element.<sup id="cite_ref-Landau_30-1" class="reference"><a href="#cite_note-Landau-30"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> They did not yet take the step of removing lanthanum from the d-block as well, but <a href="/wiki/Jun_Kond%C5%8D" title="Jun Kondō">Jun Kondō</a> realized in 1963 that lanthanum's low-temperature <a href="/wiki/Superconductivity" title="Superconductivity">superconductivity</a> implied the activity of its 4f shell.<sup id="cite_ref-Kondo_110-0" class="reference"><a href="#cite_note-Kondo-110"><span class="cite-bracket">[</span>100<span class="cite-bracket">]</span></a></sup> In 1965, David C. Hamilton linked this observation to its position in the periodic table, and argued that the f-block should be composed of the elements La–Yb and Ac–No.<sup id="cite_ref-Hamilton_72-1" class="reference"><a href="#cite_note-Hamilton-72"><span class="cite-bracket">[</span>63<span class="cite-bracket">]</span></a></sup> Since then, physical, chemical, and electronic evidence has supported this assignment.<sup id="cite_ref-Jensen1982_29-2" class="reference"><a href="#cite_note-Jensen1982-29"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Fluck_27-4" class="reference"><a href="#cite_note-Fluck-27"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-wulfsberg53_109-1" class="reference"><a href="#cite_note-wulfsberg53-109"><span class="cite-bracket">[</span>99<span class="cite-bracket">]</span></a></sup> The issue was brought to wide attention by <a href="/wiki/William_B._Jensen" title="William B. Jensen">William B. Jensen</a> in 1982,<sup id="cite_ref-Jensen1982_29-3" class="reference"><a href="#cite_note-Jensen1982-29"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> and the reassignment of lutetium and lawrencium to group 3 was supported by IUPAC reports dating from 1988 (when the 1–18 group numbers were recommended)<sup id="cite_ref-Fluck_27-5" class="reference"><a href="#cite_note-Fluck-27"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> and 2021.<sup id="cite_ref-2021IUPAC_28-2" class="reference"><a href="#cite_note-2021IUPAC-28"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> The variation nonetheless still exists because most textbook writers are not aware of the issue.<sup id="cite_ref-Jensen1982_29-4" class="reference"><a href="#cite_note-Jensen1982-29"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> </p><p>A third form can sometimes be encountered in which the spaces below yttrium in group 3 are left empty, such as the table appearing on the IUPAC web site,<sup id="cite_ref-IUPAC-redbook_7-8" class="reference"><a href="#cite_note-IUPAC-redbook-7"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> but this creates an inconsistency with quantum mechanics by making the f-block 15 elements wide (La–Lu and Ac–Lr) even though only 14 electrons can fit in an f-subshell.<sup id="cite_ref-2021IUPAC_28-3" class="reference"><a href="#cite_note-2021IUPAC-28"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> There is moreover some confusion in the literature on which elements are then implied to be in group 3.<sup id="cite_ref-2021IUPAC_28-4" class="reference"><a href="#cite_note-2021IUPAC-28"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Thyssen_37-2" class="reference"><a href="#cite_note-Thyssen-37"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-JWP_111-0" class="reference"><a href="#cite_note-JWP-111"><span class="cite-bracket">[</span>101<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Karol_112-0" class="reference"><a href="#cite_note-Karol-112"><span class="cite-bracket">[</span>102<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-113" class="reference"><a href="#cite_note-113"><span class="cite-bracket">[</span>103<span class="cite-bracket">]</span></a></sup> While the 2021 IUPAC report noted that 15-element-wide f-blocks are supported by some practitioners of a specialized branch of <a href="/wiki/Relativistic_quantum_mechanics" title="Relativistic quantum mechanics">relativistic quantum mechanics</a> focusing on the properties of <a href="/wiki/Superheavy_element" title="Superheavy element">superheavy elements</a>, the project's opinion was that such interest-dependent concerns should not have any bearing on how the periodic table is presented to "the general chemical and scientific community".<sup id="cite_ref-2021IUPAC_28-5" class="reference"><a href="#cite_note-2021IUPAC-28"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> Other authors focusing on superheavy elements since clarified that the "15th entry of the f-block represents the first slot of the d-block which is left vacant to indicate the place of the f-block inserts", which would imply that this form still has lutetium and lawrencium (the 15th entries in question) as d-block elements in group 3.<sup id="cite_ref-smits_114-0" class="reference"><a href="#cite_note-smits-114"><span class="cite-bracket">[</span>104<span class="cite-bracket">]</span></a></sup> Indeed, when IUPAC publications expand the table to 32 columns, they make this clear and place lutetium and lawrencium under yttrium in group 3.<sup id="cite_ref-115" class="reference"><a href="#cite_note-115"><span class="cite-bracket">[</span>105<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-116" class="reference"><a href="#cite_note-116"><span class="cite-bracket">[</span>106<span class="cite-bracket">]</span></a></sup> </p><p>Several arguments in favour of Sc-Y-La-Ac can be encountered in the literature,<sup id="cite_ref-117" class="reference"><a href="#cite_note-117"><span class="cite-bracket">[</span>107<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-118" class="reference"><a href="#cite_note-118"><span class="cite-bracket">[</span>108<span class="cite-bracket">]</span></a></sup> but they have been challenged as being logically inconsistent.<sup id="cite_ref-Jensen2015_31-2" class="reference"><a href="#cite_note-Jensen2015-31"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Scerri2009_32-2" class="reference"><a href="#cite_note-Scerri2009-32"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Chemey_33-1" class="reference"><a href="#cite_note-Chemey-33"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> For example, it has been argued that lanthanum and actinium cannot be f-block elements because as individual gas-phase atoms, they have not begun to fill the f-subshells.<sup id="cite_ref-Lavelle_119-0" class="reference"><a href="#cite_note-Lavelle-119"><span class="cite-bracket">[</span>109<span class="cite-bracket">]</span></a></sup> But the same is true of thorium which is never disputed as an f-block element,<sup id="cite_ref-2021IUPAC_28-6" class="reference"><a href="#cite_note-2021IUPAC-28"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Jensen1982_29-5" class="reference"><a href="#cite_note-Jensen1982-29"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> and this argument overlooks the problem on the other end: that the f-shells complete filling at ytterbium and nobelium, matching the Sc-Y-Lu-Lr form, and not at lutetium and lawrencium as the Sc-Y-La-Ac form would have it.<sup id="cite_ref-johnson_120-0" class="reference"><a href="#cite_note-johnson-120"><span class="cite-bracket">[</span>110<span class="cite-bracket">]</span></a></sup> Not only are such exceptional configurations in the minority,<sup id="cite_ref-johnson_120-1" class="reference"><a href="#cite_note-johnson-120"><span class="cite-bracket">[</span>110<span class="cite-bracket">]</span></a></sup> but they have also in any case never been considered as relevant for positioning any other elements on the periodic table: in gaseous atoms, the d-shells complete their filling at copper, palladium, and gold, but it is universally accepted by chemists that these configurations are exceptional and that the d-block really ends in accordance with the Madelung rule at zinc, cadmium, and mercury.<sup id="cite_ref-Thyssen_37-3" class="reference"><a href="#cite_note-Thyssen-37"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> The relevant fact for placement<sup id="cite_ref-Jensen2009_43-2" class="reference"><a href="#cite_note-Jensen2009-43"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-JensenLr_74-1" class="reference"><a href="#cite_note-JensenLr-74"><span class="cite-bracket">[</span>65<span class="cite-bracket">]</span></a></sup> is that lanthanum and actinium (like thorium) have valence f-orbitals that can become occupied in chemical environments, whereas lutetium and lawrencium do not:<sup id="cite_ref-jensenlaw_66-17" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Wittig_121-0" class="reference"><a href="#cite_note-Wittig-121"><span class="cite-bracket">[</span>111<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-XuPyykko_84-1" class="reference"><a href="#cite_note-XuPyykko-84"><span class="cite-bracket">[</span>74<span class="cite-bracket">]</span></a></sup> their f-shells are in the core, and cannot be used for chemical reactions.<sup id="cite_ref-Cp3Ln_73-2" class="reference"><a href="#cite_note-Cp3Ln-73"><span class="cite-bracket">[</span>64<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-wulfsberg26_122-0" class="reference"><a href="#cite_note-wulfsberg26-122"><span class="cite-bracket">[</span>112<span class="cite-bracket">]</span></a></sup> Thus the relationship between yttrium and lanthanum is only a secondary relationship between elements with the same number of valence electrons but different kinds of valence orbitals, such as that between chromium and uranium; whereas the relationship between yttrium and lutetium is primary, sharing both valence electron count and valence orbital type.<sup id="cite_ref-jensenlaw_66-18" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Periodic_trends">Periodic trends</h2></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Periodic_trends" title="Periodic trends">Periodic trends</a></div> <p>As chemical reactions involve the valence electrons,<sup id="cite_ref-cartoon_36-2" class="reference"><a href="#cite_note-cartoon-36"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> elements with similar outer electron configurations may be expected to react similarly and form compounds with similar proportions of elements in them.<sup id="cite_ref-Greenwood27_123-0" class="reference"><a href="#cite_note-Greenwood27-123"><span class="cite-bracket">[</span>113<span class="cite-bracket">]</span></a></sup> Such elements are placed in the same group, and thus there tend to be clear similarities and trends in chemical behaviour as one proceeds down a group.<sup id="cite_ref-124" class="reference"><a href="#cite_note-124"><span class="cite-bracket">[</span>114<span class="cite-bracket">]</span></a></sup> As analogous configurations occur at regular intervals, the properties of the elements thus exhibit periodic recurrences, hence the name of the periodic table and the periodic law. These periodic recurrences were noticed well before the underlying theory that explains them was developed.<sup id="cite_ref-Myers_125-0" class="reference"><a href="#cite_note-Myers-125"><span class="cite-bracket">[</span>115<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-chang2_126-0" class="reference"><a href="#cite_note-chang2-126"><span class="cite-bracket">[</span>116<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Atomic_radius">Atomic radius</h3></div> <p>Historically, the physical size of atoms was unknown until the early 20th century. The first calculated estimate of the atomic radius of hydrogen was published by physicist <a href="/wiki/Arthur_Erich_Haas" title="Arthur Erich Haas">Arthur Haas</a> in 1910 to within an order of magnitude (a factor of 10) of the accepted value, the <a href="/wiki/Bohr_radius" title="Bohr radius">Bohr radius</a> (~0.529 Å). In his model, Haas used a single-electron configuration based on the classical atomic model proposed by <a href="/wiki/J._J._Thomson" title="J. J. Thomson">J. J. Thomson</a> in 1904, often called the <a href="/wiki/Plum-pudding_model" class="mw-redirect" title="Plum-pudding model">plum-pudding model</a>.<sup id="cite_ref-127" class="reference"><a href="#cite_note-127"><span class="cite-bracket">[</span>117<span class="cite-bracket">]</span></a></sup> </p><p><a href="/wiki/Atomic_radius" title="Atomic radius">Atomic radii</a> (the size of atoms) are dependent on the sizes of their outermost orbitals.<sup id="cite_ref-SB23_106-1" class="reference"><a href="#cite_note-SB23-106"><span class="cite-bracket">[</span>96<span class="cite-bracket">]</span></a></sup> They generally decrease going left to right along the main-group elements, because the nuclear charge increases but the outer electrons are still in the same shell. However, going down a column, the radii generally increase, because the outermost electrons are in higher shells that are thus further away from the nucleus.<sup id="cite_ref-cartoon_36-3" class="reference"><a href="#cite_note-cartoon-36"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-chemguidear_128-0" class="reference"><a href="#cite_note-chemguidear-128"><span class="cite-bracket">[</span>118<span class="cite-bracket">]</span></a></sup> The first row of each block is abnormally small, due to an effect called <a href="/wiki/Kainosymmetry" title="Kainosymmetry">kainosymmetry</a> or primogenic repulsion:<sup id="cite_ref-129" class="reference"><a href="#cite_note-129"><span class="cite-bracket">[</span>119<span class="cite-bracket">]</span></a></sup> the 1s, 2p, 3d, and 4f subshells have no inner analogues. For example, the 2p orbitals do not experience strong repulsion from the 1s and 2s orbitals, which have quite different angular charge distributions, and hence are not very large; but the 3p orbitals experience strong repulsion from the 2p orbitals, which have similar angular charge distributions. Thus higher s-, p-, d-, and f-subshells experience strong repulsion from their inner analogues, which have approximately the same angular distribution of charge, and must expand to avoid this. This makes significant differences arise between the small 2p elements, which prefer <a href="/wiki/Multiple_bond" class="mw-redirect" title="Multiple bond">multiple bonding</a>, and the larger 3p and higher p-elements, which do not.<sup id="cite_ref-SB23_106-2" class="reference"><a href="#cite_note-SB23-106"><span class="cite-bracket">[</span>96<span class="cite-bracket">]</span></a></sup> Similar anomalies arise for the 1s, 2p, 3d, 4f, and the hypothetical 5g elements:<sup id="cite_ref-Kaupp_130-0" class="reference"><a href="#cite_note-Kaupp-130"><span class="cite-bracket">[</span>120<span class="cite-bracket">]</span></a></sup> the degree of this first-row anomaly is highest for the s-block, is moderate for the p-block, and is less pronounced for the d- and f-blocks.<sup id="cite_ref-PTSS2_131-0" class="reference"><a href="#cite_note-PTSS2-131"><span class="cite-bracket">[</span>121<span class="cite-bracket">]</span></a></sup> </p><p>In the transition elements, an inner shell is filling, but the size of the atom is still determined by the outer electrons. The increasing nuclear charge across the series and the increased number of inner electrons for shielding somewhat compensate each other, so the decrease in radius is smaller.<sup id="cite_ref-chemguidear_128-1" class="reference"><a href="#cite_note-chemguidear-128"><span class="cite-bracket">[</span>118<span class="cite-bracket">]</span></a></sup> The 4p and 5d atoms, coming immediately after new types of transition series are first introduced, are smaller than would have been expected,<sup id="cite_ref-Greenwood29_132-0" class="reference"><a href="#cite_note-Greenwood29-132"><span class="cite-bracket">[</span>122<span class="cite-bracket">]</span></a></sup> because the added core 3d and 4f subshells provide only incomplete shielding of the nuclear charge for the outer electrons. Hence for example gallium atoms are slightly smaller than aluminium atoms.<sup id="cite_ref-SB23_106-3" class="reference"><a href="#cite_note-SB23-106"><span class="cite-bracket">[</span>96<span class="cite-bracket">]</span></a></sup> Together with kainosymmetry, this results in an even-odd difference between the periods (except in the s-block)<sup id="cite_ref-133" class="reference"><a href="#cite_note-133"><span class="cite-bracket">[</span>k<span class="cite-bracket">]</span></a></sup> that is sometimes known as secondary periodicity: elements in even periods have smaller atomic radii and prefer to lose fewer electrons, while elements in odd periods (except the first) differ in the opposite direction. Thus for example many properties in the p-block show a zigzag rather than a smooth trend along the group. For example, phosphorus and antimony in odd periods of group 15 readily reach the +5 oxidation state, whereas nitrogen, arsenic, and bismuth in even periods prefer to stay at +3.<sup id="cite_ref-PTSS2_131-1" class="reference"><a href="#cite_note-PTSS2-131"><span class="cite-bracket">[</span>121<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-134" class="reference"><a href="#cite_note-134"><span class="cite-bracket">[</span>123<span class="cite-bracket">]</span></a></sup> A similar situation holds for the d-block, with lutetium through tungsten atoms being slightly smaller than yttrium through molybdenum atoms respectively.<sup id="cite_ref-135" class="reference"><a href="#cite_note-135"><span class="cite-bracket">[</span>124<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Calc1_136-0" class="reference"><a href="#cite_note-Calc1-136"><span class="cite-bracket">[</span>125<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Pouring_liquid_mercury_bionerd.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/99/Pouring_liquid_mercury_bionerd.jpg/220px-Pouring_liquid_mercury_bionerd.jpg" decoding="async" width="220" height="239" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/99/Pouring_liquid_mercury_bionerd.jpg/330px-Pouring_liquid_mercury_bionerd.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/99/Pouring_liquid_mercury_bionerd.jpg/440px-Pouring_liquid_mercury_bionerd.jpg 2x" data-file-width="1209" data-file-height="1311" /></a><figcaption>Liquid mercury. Its liquid state at standard conditions is the result of relativistic effects.<sup id="cite_ref-PekkaPyykko_137-0" class="reference"><a href="#cite_note-PekkaPyykko-137"><span class="cite-bracket">[</span>126<span class="cite-bracket">]</span></a></sup></figcaption></figure> <p>Thallium and lead atoms are about the same size as indium and tin atoms respectively, but from bismuth to radon the 6p atoms are larger than the analogous 5p atoms. This happens because when atomic nuclei become highly charged, <a href="/wiki/Special_relativity" title="Special relativity">special relativity</a> becomes needed to gauge the effect of the nucleus on the electron cloud. These <a href="/wiki/Relativistic_quantum_chemistry" title="Relativistic quantum chemistry">relativistic effects</a> result in heavy elements increasingly having differing properties compared to their lighter homologues in the periodic table. <a href="/wiki/Spin%E2%80%93orbit_interaction" title="Spin–orbit interaction">Spin–orbit interaction</a> splits the p-subshell: one p-orbital is relativistically stabilized and shrunken (it fills in thallium and lead), but the other two (filling in bismuth through radon) are relativistically destabilized and expanded.<sup id="cite_ref-SB23_106-5" class="reference"><a href="#cite_note-SB23-106"><span class="cite-bracket">[</span>96<span class="cite-bracket">]</span></a></sup> Relativistic effects also explain why <a href="/wiki/Gold" title="Gold">gold</a> is golden and <a href="/wiki/Mercury_(element)" title="Mercury (element)">mercury</a> is a liquid at room temperature.<sup id="cite_ref-PekkaPyykko_137-1" class="reference"><a href="#cite_note-PekkaPyykko-137"><span class="cite-bracket">[</span>126<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Norrby_138-0" class="reference"><a href="#cite_note-Norrby-138"><span class="cite-bracket">[</span>127<span class="cite-bracket">]</span></a></sup> They are expected to become very strong in the late seventh period, potentially leading to a collapse of periodicity.<sup id="cite_ref-actrev_139-0" class="reference"><a href="#cite_note-actrev-139"><span class="cite-bracket">[</span>128<span class="cite-bracket">]</span></a></sup> Electron configurations are only clearly known until element 108 (<a href="/wiki/Hassium" title="Hassium">hassium</a>), and experimental chemistry beyond 108 has only been done for 112 (<a href="/wiki/Copernicium" title="Copernicium">copernicium</a>), 113 (<a href="/wiki/Nihonium" title="Nihonium">nihonium</a>), and 114 (<a href="/wiki/Flerovium" title="Flerovium">flerovium</a>), so the chemical characterization of the heaviest elements remains a topic of current research.<sup id="cite_ref-Schändel_2003_277_140-0" class="reference"><a href="#cite_note-Schändel_2003_277-140"><span class="cite-bracket">[</span>129<span class="cite-bracket">]</span></a></sup> </p><p>The trend that atomic radii decrease from left to right is also present in <a href="/wiki/Ionic_radius" title="Ionic radius">ionic radii</a>, though it is more difficult to examine because the most common ions of consecutive elements normally differ in charge. Ions with the same electron configuration decrease in size as their atomic number rises, due to increased attraction from the more positively charged nucleus: thus for example ionic radii decrease in the series Se<sup>2−</sup>, Br<sup>−</sup>, Rb<sup>+</sup>, Sr<sup>2+</sup>, Y<sup>3+</sup>, Zr<sup>4+</sup>, Nb<sup>5+</sup>, Mo<sup>6+</sup>, Tc<sup>7+</sup>. Ions of the same element get smaller as more electrons are removed, because the attraction from the nucleus begins to outweigh the repulsion between electrons that causes electron clouds to expand: thus for example ionic radii decrease in the series V<sup>2+</sup>, V<sup>3+</sup>, V<sup>4+</sup>, V<sup>5+</sup>.<sup id="cite_ref-141" class="reference"><a href="#cite_note-141"><span class="cite-bracket">[</span>130<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Ionisation_energy">Ionisation energy</h3></div> <figure class="mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:First_Ionization_Energy_blocks.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b6/First_Ionization_Energy_blocks.svg/512px-First_Ionization_Energy_blocks.svg.png" decoding="async" width="512" height="190" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b6/First_Ionization_Energy_blocks.svg/768px-First_Ionization_Energy_blocks.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b6/First_Ionization_Energy_blocks.svg/1024px-First_Ionization_Energy_blocks.svg.png 2x" data-file-width="512" data-file-height="190" /></a><figcaption>Graph of first ionisation energies of the elements in electronvolts (predictions used for elements 109–118)</figcaption></figure> <p>The first <a href="/wiki/Ionisation_energy" class="mw-redirect" title="Ionisation energy">ionisation energy</a> of an atom is the energy required to remove an electron from it. This varies with the atomic radius: ionisation energy increases left to right and down to up, because electrons that are closer to the nucleus are held more tightly and are more difficult to remove. Ionisation energy thus is minimized at the first element of each period – hydrogen and the <a href="/wiki/Alkali_metal" title="Alkali metal">alkali metals</a> – and then generally rises until it reaches the <a href="/wiki/Noble_gas" title="Noble gas">noble gas</a> at the right edge of the period.<sup id="cite_ref-cartoon_36-4" class="reference"><a href="#cite_note-cartoon-36"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> There are some exceptions to this trend, such as oxygen, where the electron being removed is paired and thus interelectronic repulsion makes it easier to remove than expected.<sup id="cite_ref-Greenwood294_142-0" class="reference"><a href="#cite_note-Greenwood294-142"><span class="cite-bracket">[</span>131<span class="cite-bracket">]</span></a></sup> </p><p>In the transition series, the outer electrons are preferentially lost even though the inner orbitals are filling. For example, in the 3d series, the 4s electrons are lost first even though the 3d orbitals are being filled. The shielding effect of adding an extra 3d electron approximately compensates the rise in nuclear charge, and therefore the ionisation energies stay mostly constant, though there is a small increase especially at the end of each transition series.<sup id="cite_ref-chemguideIE_143-0" class="reference"><a href="#cite_note-chemguideIE-143"><span class="cite-bracket">[</span>132<span class="cite-bracket">]</span></a></sup> </p><p>As metal atoms tend to lose electrons in chemical reactions, ionisation energy is generally correlated with chemical reactivity, although there are other factors involved as well.<sup id="cite_ref-chemguideIE_143-1" class="reference"><a href="#cite_note-chemguideIE-143"><span class="cite-bracket">[</span>132<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Electron_affinity">Electron affinity</h3></div> <figure class="mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Electron_affinity_of_the_elements.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/6c/Electron_affinity_of_the_elements.svg/384px-Electron_affinity_of_the_elements.svg.png" decoding="async" width="384" height="202" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/6c/Electron_affinity_of_the_elements.svg/576px-Electron_affinity_of_the_elements.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/6c/Electron_affinity_of_the_elements.svg/768px-Electron_affinity_of_the_elements.svg.png 2x" data-file-width="1050" data-file-height="552" /></a><figcaption>Trend in electron affinities</figcaption></figure> <p>The opposite property to ionisation energy is the <a href="/wiki/Electron_affinity" title="Electron affinity">electron affinity</a>, which is the energy released when adding an electron to the atom.<sup id="cite_ref-chemguideea_144-0" class="reference"><a href="#cite_note-chemguideea-144"><span class="cite-bracket">[</span>133<span class="cite-bracket">]</span></a></sup> A passing electron will be more readily attracted to an atom if it feels the pull of the nucleus more strongly, and especially if there is an available partially filled outer orbital that can accommodate it. Therefore, electron affinity tends to increase down to up and left to right. The exception is the last column, the noble gases, which have a full shell and have no room for another electron. This gives the <a href="/wiki/Halogen" title="Halogen">halogens</a> in the next-to-last column the highest electron affinities.<sup id="cite_ref-cartoon_36-5" class="reference"><a href="#cite_note-cartoon-36"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> </p><p>Some atoms, like the noble gases, have no electron affinity: they cannot form stable gas-phase anions.<sup id="cite_ref-145" class="reference"><a href="#cite_note-145"><span class="cite-bracket">[</span>134<span class="cite-bracket">]</span></a></sup> (They can form metastable <a href="/wiki/Resonance_(particle_physics)" title="Resonance (particle physics)">resonances</a> if the incoming electron arrives with enough kinetic energy, but these inevitably and rapidly <a href="/wiki/Autoionization" title="Autoionization">autodetach</a>: for example, the lifetime of the most long-lived He<sup>−</sup> level is about 359 microseconds.)<sup id="cite_ref-146" class="reference"><a href="#cite_note-146"><span class="cite-bracket">[</span>135<span class="cite-bracket">]</span></a></sup> The noble gases, having high ionisation energies and no electron affinity, have little inclination towards gaining or losing electrons and are generally unreactive.<sup id="cite_ref-cartoon_36-6" class="reference"><a href="#cite_note-cartoon-36"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> </p><p>Some exceptions to the trends occur: oxygen and fluorine have lower electron affinities than their heavier homologues sulfur and chlorine, because they are small atoms and hence the newly added electron would experience significant repulsion from the already present ones. For the nonmetallic elements, electron affinity likewise somewhat correlates with reactivity, but not perfectly since other factors are involved. For example, fluorine has a lower electron affinity than chlorine (because of extreme interelectronic repulsion for the very small fluorine atom), but is more reactive.<sup id="cite_ref-chemguideea_144-1" class="reference"><a href="#cite_note-chemguideea-144"><span class="cite-bracket">[</span>133<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Valence_and_oxidation_states">Valence and oxidation states</h3></div> <style data-mw-deduplicate="TemplateStyles:r1237032888/mw-parser-output/.tmulti">.mw-parser-output .tmulti .multiimageinner{display:flex;flex-direction:column}.mw-parser-output .tmulti .trow{display:flex;flex-direction:row;clear:left;flex-wrap:wrap;width:100%;box-sizing:border-box}.mw-parser-output .tmulti .tsingle{margin:1px;float:left}.mw-parser-output .tmulti .theader{clear:both;font-weight:bold;text-align:center;align-self:center;background-color:transparent;width:100%}.mw-parser-output .tmulti .thumbcaption{background-color:transparent}.mw-parser-output .tmulti .text-align-left{text-align:left}.mw-parser-output .tmulti .text-align-right{text-align:right}.mw-parser-output .tmulti .text-align-center{text-align:center}@media all and (max-width:720px){.mw-parser-output .tmulti .thumbinner{width:100%!important;box-sizing:border-box;max-width:none!important;align-items:center}.mw-parser-output .tmulti .trow{justify-content:center}.mw-parser-output .tmulti .tsingle{float:none!important;max-width:100%!important;box-sizing:border-box;text-align:center}.mw-parser-output .tmulti .tsingle .thumbcaption{text-align:left}.mw-parser-output .tmulti .trow>.thumbcaption{text-align:center}}@media screen{html.skin-theme-clientpref-night .mw-parser-output .tmulti .multiimageinner img{background-color:white}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .tmulti .multiimageinner img{background-color:white}}</style><div class="thumb tmulti tright"><div class="thumbinner multiimageinner" style="width:248px;max-width:248px"><div class="trow"><div class="tsingle" style="width:127px;max-width:127px"><div class="thumbimage" style="height:99px;overflow:hidden"><span typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Oxid_olovnat%C3%BD.JPG/125px-Oxid_olovnat%C3%BD.JPG" decoding="async" width="125" height="100" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Oxid_olovnat%C3%BD.JPG/188px-Oxid_olovnat%C3%BD.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Oxid_olovnat%C3%BD.JPG/250px-Oxid_olovnat%C3%BD.JPG 2x" data-file-width="603" data-file-height="480" /></span></span></div></div><div class="tsingle" style="width:117px;max-width:117px"><div class="thumbimage" style="height:99px;overflow:hidden"><span typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/d/df/Lead_dioxide.jpg/115px-Lead_dioxide.jpg" decoding="async" width="115" height="99" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/df/Lead_dioxide.jpg/173px-Lead_dioxide.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/df/Lead_dioxide.jpg/230px-Lead_dioxide.jpg 2x" data-file-width="692" data-file-height="598" /></span></span></div></div></div><div class="trow" style="display:flex"><div class="thumbcaption"><a href="/wiki/Lead(II)_oxide" title="Lead(II) oxide">Lead(II) oxide</a> (PbO, left) and <a href="/wiki/Lead(IV)_oxide" class="mw-redirect" title="Lead(IV) oxide">lead(IV) oxide</a> (PbO<sub>2</sub>, right), the two stable oxides of <a href="/wiki/Lead" title="Lead">lead</a></div></div></div></div> <p>The <a href="/wiki/Valence_(chemistry)" title="Valence (chemistry)">valence</a> of an element can be defined either as the number of hydrogen atoms that can combine with it to form a simple binary hydride, or as twice the number of oxygen atoms that can combine with it to form a simple binary oxide (that is, not a <a href="/wiki/Peroxide" title="Peroxide">peroxide</a> or a <a href="/wiki/Superoxide" title="Superoxide">superoxide</a>).<sup id="cite_ref-johnson_120-2" class="reference"><a href="#cite_note-johnson-120"><span class="cite-bracket">[</span>110<span class="cite-bracket">]</span></a></sup> The valences of the main-group elements are directly related to the group number: the hydrides in the main groups 1–2 and 13–17 follow the formulae MH, MH<sub>2</sub>, MH<sub>3</sub>, MH<sub>4</sub>, MH<sub>3</sub>, MH<sub>2</sub>, and finally MH. The highest oxides instead increase in valence, following the formulae M<sub>2</sub>O, MO, M<sub>2</sub>O<sub>3</sub>, MO<sub>2</sub>, M<sub>2</sub>O<sub>5</sub>, MO<sub>3</sub>, M<sub>2</sub>O<sub>7</sub>.<sup id="cite_ref-147" class="reference"><a href="#cite_note-147"><span class="cite-bracket">[</span>l<span class="cite-bracket">]</span></a></sup> Today the notion of valence has been extended by that of the <a href="/wiki/Oxidation_state" title="Oxidation state">oxidation state</a>, which is the formal charge left on an element when all other elements in a compound have been removed as their ions.<sup id="cite_ref-Greenwood27_123-2" class="reference"><a href="#cite_note-Greenwood27-123"><span class="cite-bracket">[</span>113<span class="cite-bracket">]</span></a></sup> </p><p>The electron configuration suggests a ready explanation from the number of electrons available for bonding;<sup id="cite_ref-Greenwood27_123-3" class="reference"><a href="#cite_note-Greenwood27-123"><span class="cite-bracket">[</span>113<span class="cite-bracket">]</span></a></sup> indeed, the number of valence electrons starts at 1 in group 1, and then increases towards the right side of the periodic table, only resetting at 3 whenever each new block starts. Thus in period 6, Cs–Ba have 1–2 valence electrons; La–Yb have 3–16; Lu–Hg have 3–12; and Tl–Rn have 3–8.<sup id="cite_ref-wulfsberg26_122-1" class="reference"><a href="#cite_note-wulfsberg26-122"><span class="cite-bracket">[</span>112<span class="cite-bracket">]</span></a></sup> However, towards the right side of the d- and f-blocks, the theoretical maximum corresponding to using all valence electrons is not achievable at all;<sup id="cite_ref-148" class="reference"><a href="#cite_note-148"><span class="cite-bracket">[</span>136<span class="cite-bracket">]</span></a></sup> the same situation affects oxygen, fluorine, and the light noble gases up to krypton.<sup id="cite_ref-149" class="reference"><a href="#cite_note-149"><span class="cite-bracket">[</span>137<span class="cite-bracket">]</span></a></sup> </p> <table class="wikitable" style="margin:auto;text-align:center;"> <caption>Number of valence electrons </caption> <tbody><tr> <th> </th> <th><a href="/wiki/Alkali_metal" title="Alkali metal">1</a> </th> <th><a href="/wiki/Alkaline_earth_metal" title="Alkaline earth metal">2</a> </th> <th colspan="14"> </th> <th><a href="/wiki/Group_3_element" title="Group 3 element">3</a> </th> <th><a href="/wiki/Group_4_element" title="Group 4 element">4</a> </th> <th><a href="/wiki/Group_5_element" title="Group 5 element">5</a> </th> <th><a href="/wiki/Group_6_element" title="Group 6 element">6</a> </th> <th><a href="/wiki/Group_7_element" title="Group 7 element">7</a> </th> <th><a href="/wiki/Group_8_element" title="Group 8 element">8</a> </th> <th><a href="/wiki/Group_9_element" title="Group 9 element">9</a> </th> <th><a href="/wiki/Group_10_element" title="Group 10 element">10</a> </th> <th><a href="/wiki/Group_11_element" title="Group 11 element">11</a> </th> <th><a href="/wiki/Group_12_element" title="Group 12 element">12</a> </th> <th><a href="/wiki/Boron_group" title="Boron group">13</a> </th> <th><a href="/wiki/Carbon_group" title="Carbon group">14</a> </th> <th><a href="/wiki/Pnictogen" title="Pnictogen">15</a> </th> <th><a href="/wiki/Chalcogen" title="Chalcogen">16</a> </th> <th><a href="/wiki/Halogen" title="Halogen">17</a> </th> <th><a href="/wiki/Noble_gas" title="Noble gas">18</a> </th></tr> <tr> <th><a href="/wiki/Period_1_element" title="Period 1 element">1</a> </th> <td bgcolor="#ff9999">H<br />1 </td> <td colspan="30" style="border-width:0"> </td> <td bgcolor="#ff9999">He<br />2 </td></tr> <tr> <th><a href="/wiki/Period_2_element" title="Period 2 element">2</a> </th> <td bgcolor="#ff9999">Li<br />1 </td> <td bgcolor="#ff9999">Be<br />2 </td> <td colspan="24" style="border-width:0"> </td> <td bgcolor="#fdff8c">B<br />3 </td> <td bgcolor="#fdff8c">C<br />4 </td> <td bgcolor="#fdff8c">N<br />5 </td> <td bgcolor="#fdff8c">O<br />6 </td> <td bgcolor="#fdff8c">F<br />7 </td> <td bgcolor="#fdff8c">Ne<br />8 </td></tr> <tr> <th><a href="/wiki/Period_3_element" title="Period 3 element">3</a> </th> <td bgcolor="#ff9999">Na<br />1 </td> <td bgcolor="#ff9999">Mg<br />2 </td> <td colspan="24" style="border-width:0"> </td> <td bgcolor="#fdff8c">Al<br />3 </td> <td bgcolor="#fdff8c">Si<br />4 </td> <td bgcolor="#fdff8c">P<br />5 </td> <td bgcolor="#fdff8c">S<br />6 </td> <td bgcolor="#fdff8c">Cl<br />7 </td> <td bgcolor="#fdff8c">Ar<br />8 </td></tr> <tr> <th><a href="/wiki/Period_4_element" title="Period 4 element">4</a> </th> <td bgcolor="#ff9999">K<br />1 </td> <td bgcolor="#ff9999">Ca<br />2 </td> <td colspan="14" style="border-width:0"> </td> <td bgcolor="#99ccff">Sc<br />3 </td> <td bgcolor="#99ccff">Ti<br />4 </td> <td bgcolor="#99ccff">V<br />5 </td> <td bgcolor="#99ccff">Cr<br />6 </td> <td bgcolor="#99ccff">Mn<br />7 </td> <td bgcolor="#99ccff">Fe<br />8 </td> <td bgcolor="#99ccff">Co<br />9 </td> <td bgcolor="#99ccff">Ni<br />10 </td> <td bgcolor="#99ccff">Cu<br />11 </td> <td bgcolor="#99ccff">Zn<br />12 </td> <td bgcolor="#fdff8c">Ga<br />3 </td> <td bgcolor="#fdff8c">Ge<br />4 </td> <td bgcolor="#fdff8c">As<br />5 </td> <td bgcolor="#fdff8c">Se<br />6 </td> <td bgcolor="#fdff8c">Br<br />7 </td> <td bgcolor="#fdff8c">Kr<br />8 </td></tr> <tr> <th><a href="/wiki/Period_5_element" title="Period 5 element">5</a> </th> <td bgcolor="#ff9999">Rb<br />1 </td> <td bgcolor="#ff9999">Sr<br />2 </td> <td colspan="14" style="border-width:0"> </td> <td bgcolor="#99ccff">Y<br />3 </td> <td bgcolor="#99ccff">Zr<br />4 </td> <td bgcolor="#99ccff">Nb<br />5 </td> <td bgcolor="#99ccff">Mo<br />6 </td> <td bgcolor="#99ccff">Tc<br />7 </td> <td bgcolor="#99ccff">Ru<br />8 </td> <td bgcolor="#99ccff">Rh<br />9 </td> <td bgcolor="#99ccff">Pd<br />10 </td> <td bgcolor="#99ccff">Ag<br />11 </td> <td bgcolor="#99ccff">Cd<br />12 </td> <td bgcolor="#fdff8c">In<br />3 </td> <td bgcolor="#fdff8c">Sn<br />4 </td> <td bgcolor="#fdff8c">Sb<br />5 </td> <td bgcolor="#fdff8c">Te<br />6 </td> <td bgcolor="#fdff8c">I<br />7 </td> <td bgcolor="#fdff8c">Xe<br />8 </td></tr> <tr> <th><a href="/wiki/Period_6_element" title="Period 6 element">6</a> </th> <td bgcolor="#ff9999">Cs<br />1 </td> <td bgcolor="#ff9999">Ba<br />2 </td> <td bgcolor="#9bff99">La<br />3 </td> <td bgcolor="#9bff99">Ce<br />4 </td> <td bgcolor="#9bff99">Pr<br />5 </td> <td bgcolor="#9bff99">Nd<br />6 </td> <td bgcolor="#9bff99">Pm<br />7 </td> <td bgcolor="#9bff99">Sm<br />8 </td> <td bgcolor="#9bff99">Eu<br />9 </td> <td bgcolor="#9bff99">Gd<br />10 </td> <td bgcolor="#9bff99">Tb<br />11 </td> <td bgcolor="#9bff99">Dy<br />12 </td> <td bgcolor="#9bff99">Ho<br />13 </td> <td bgcolor="#9bff99">Er<br />14 </td> <td bgcolor="#9bff99">Tm<br />15 </td> <td bgcolor="#9bff99">Yb<br />16 </td> <td bgcolor="#99ccff">Lu<br />3 </td> <td bgcolor="#99ccff">Hf<br />4 </td> <td bgcolor="#99ccff">Ta<br />5 </td> <td bgcolor="#99ccff">W<br />6 </td> <td bgcolor="#99ccff">Re<br />7 </td> <td bgcolor="#99ccff">Os<br />8 </td> <td bgcolor="#99ccff">Ir<br />9 </td> <td bgcolor="#99ccff">Pt<br />10 </td> <td bgcolor="#99ccff">Au<br />11 </td> <td bgcolor="#99ccff">Hg<br />12 </td> <td bgcolor="#fdff8c">Tl<br />3 </td> <td bgcolor="#fdff8c">Pb<br />4 </td> <td bgcolor="#fdff8c">Bi<br />5 </td> <td bgcolor="#fdff8c">Po<br />6 </td> <td bgcolor="#fdff8c">At<br />7 </td> <td bgcolor="#fdff8c">Rn<br />8 </td></tr> <tr> <th><a href="/wiki/Period_7_element" title="Period 7 element">7</a> </th> <td bgcolor="#ff9999">Fr<br />1 </td> <td bgcolor="#ff9999">Ra<br />2 </td> <td bgcolor="#9bff99">Ac<br />3 </td> <td bgcolor="#9bff99">Th<br />4 </td> <td bgcolor="#9bff99">Pa<br />5 </td> <td bgcolor="#9bff99">U<br />6 </td> <td bgcolor="#9bff99">Np<br />7 </td> <td bgcolor="#9bff99">Pu<br />8 </td> <td bgcolor="#9bff99">Am<br />9 </td> <td bgcolor="#9bff99">Cm<br />10 </td> <td bgcolor="#9bff99">Bk<br />11 </td> <td bgcolor="#9bff99">Cf<br />12 </td> <td bgcolor="#9bff99">Es<br />13 </td> <td bgcolor="#9bff99">Fm<br />14 </td> <td bgcolor="#9bff99">Md<br />15 </td> <td bgcolor="#9bff99">No<br />16 </td> <td bgcolor="#99ccff">Lr<br />3 </td> <td bgcolor="#99ccff">Rf<br />4 </td> <td bgcolor="#99ccff">Db<br />5 </td> <td bgcolor="#99ccff">Sg<br />6 </td> <td bgcolor="#99ccff">Bh<br />7 </td> <td bgcolor="#99ccff">Hs<br />8 </td> <td bgcolor="#99ccff">Mt<br />9 </td> <td bgcolor="#99ccff">Ds<br />10 </td> <td bgcolor="#99ccff">Rg<br />11 </td> <td bgcolor="#99ccff">Cn<br />12 </td> <td bgcolor="#fdff8c">Nh<br />3 </td> <td bgcolor="#fdff8c">Fl<br />4 </td> <td bgcolor="#fdff8c">Mc<br />5 </td> <td bgcolor="#fdff8c">Lv<br />6 </td> <td bgcolor="#fdff8c">Ts<br />7 </td> <td bgcolor="#fdff8c">Og<br />8 </td></tr></tbody></table> <p>A full explanation requires considering the energy that would be released in forming compounds with different valences rather than simply considering electron configurations alone.<sup id="cite_ref-Greenwood113_150-0" class="reference"><a href="#cite_note-Greenwood113-150"><span class="cite-bracket">[</span>138<span class="cite-bracket">]</span></a></sup> For example, magnesium forms Mg<sup>2+</sup> rather than Mg<sup>+</sup> cations when dissolved in water, because the latter would spontaneously <a href="/wiki/Disproportionation" title="Disproportionation">disproportionate</a> into Mg<sup>0</sup> and Mg<sup>2+</sup> cations. This is because the <a href="/wiki/Enthalpy" title="Enthalpy">enthalpy</a> of hydration (surrounding the cation with water molecules) increases in magnitude with the charge and radius of the ion. In Mg<sup>+</sup>, the outermost orbital (which determines ionic radius) is still 3s, so the hydration enthalpy is small and insufficient to compensate the energy required to remove the electron; but ionizing again to Mg<sup>2+</sup> uncovers the core 2p subshell, making the hydration enthalpy large enough to allow magnesium(II) compounds to form. For similar reasons, the common oxidation states of the heavier p-block elements (where the ns electrons become lower in energy than the np) tend to vary by steps of 2, because that is necessary to uncover an inner subshell and decrease the ionic radius (e.g. Tl<sup>+</sup> uncovers 6s, and Tl<sup>3+</sup> uncovers 5d, so once thallium loses two electrons it tends to lose the third one as well). Analogous arguments based on <a href="/wiki/Orbital_hybridization" class="mw-redirect" title="Orbital hybridization">orbital hybridization</a> can be used for the less electronegative p-block elements.<sup id="cite_ref-sb45_151-0" class="reference"><a href="#cite_note-sb45-151"><span class="cite-bracket">[</span>139<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-153" class="reference"><a href="#cite_note-153"><span class="cite-bracket">[</span>m<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-halign-center" typeof="mw:File/Frame"><a href="/wiki/File:Transition_metal_oxidation_states.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/43/Transition_metal_oxidation_states.svg/800px-Transition_metal_oxidation_states.svg.png" decoding="async" width="800" height="300" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/43/Transition_metal_oxidation_states.svg/1200px-Transition_metal_oxidation_states.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/43/Transition_metal_oxidation_states.svg/1600px-Transition_metal_oxidation_states.svg.png 2x" data-file-width="800" data-file-height="300" /></a><figcaption>Oxidation states of the transition metals. The solid dots show common oxidation states, and the hollow dots show possible but unlikely states.</figcaption></figure> <p>For transition metals, common oxidation states are nearly always at least +2 for similar reasons (uncovering the next subshell); this holds even for the metals with anomalous d<sup>x+1</sup>s<sup>1</sup> or d<sup>x+2</sup>s<sup>0</sup> configurations (except for <a href="/wiki/Silver" title="Silver">silver</a>), because repulsion between d-electrons means that the movement of the second electron from the s- to the d-subshell does not appreciably change its ionisation energy.<sup id="cite_ref-sb134_154-0" class="reference"><a href="#cite_note-sb134-154"><span class="cite-bracket">[</span>141<span class="cite-bracket">]</span></a></sup> Because ionizing the transition metals further does not uncover any new inner subshells, their oxidation states tend to vary by steps of 1 instead.<sup id="cite_ref-sb45_151-2" class="reference"><a href="#cite_note-sb45-151"><span class="cite-bracket">[</span>139<span class="cite-bracket">]</span></a></sup> The lanthanides and late actinides generally show a stable +3 oxidation state, removing the outer s-electrons and then (usually) one electron from the (n−2)f-orbitals, that are similar in energy to ns.<sup id="cite_ref-sb178_155-0" class="reference"><a href="#cite_note-sb178-155"><span class="cite-bracket">[</span>142<span class="cite-bracket">]</span></a></sup> The common and maximum oxidation states of the d- and f-block elements tend to depend on the ionisation energies. As the energy difference between the (n−1)d and ns orbitals rises along each transition series, it becomes less energetically favourable to ionize further electrons. Thus, the early transition metal groups tend to prefer higher oxidation states, but the +2 oxidation state becomes more stable for the late transition metal groups. The highest formal oxidation state thus increases from +3 at the beginning of each d-block row, to +7 or +8 in the middle (e.g. <a href="/wiki/Osmium_tetroxide" title="Osmium tetroxide">OsO<sub>4</sub></a>), and then decrease to +2 at the end.<sup id="cite_ref-sb134_154-1" class="reference"><a href="#cite_note-sb134-154"><span class="cite-bracket">[</span>141<span class="cite-bracket">]</span></a></sup> The lanthanides and late actinides usually have high fourth ionisation energies and hence rarely surpass the +3 oxidation state, whereas early actinides have low fourth ionisation energies and so for example neptunium and plutonium can reach +7.<sup id="cite_ref-johnson_120-3" class="reference"><a href="#cite_note-johnson-120"><span class="cite-bracket">[</span>110<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-sb134_154-2" class="reference"><a href="#cite_note-sb134-154"><span class="cite-bracket">[</span>141<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-sb178_155-1" class="reference"><a href="#cite_note-sb178-155"><span class="cite-bracket">[</span>142<span class="cite-bracket">]</span></a></sup> The very last actinides go further than the lanthanides towards low oxidation states: mendelevium is more easily reduced to the +2 state than thulium or even europium (the lanthanide with the most stable +2 state, on account of its half-filled f-shell), and nobelium outright favours +2 over +3, in contrast to ytterbium.<sup id="cite_ref-rareearths_61-2" class="reference"><a href="#cite_note-rareearths-61"><span class="cite-bracket">[</span>54<span class="cite-bracket">]</span></a></sup> </p><p>As elements in the same group share the same valence configurations, they usually exhibit similar chemical behaviour. For example, the <a href="/wiki/Alkali_metal" title="Alkali metal">alkali metals</a> in the first group all have one valence electron, and form a very homogeneous class of elements: they are all soft and reactive metals. However, there are many factors involved, and groups can often be rather heterogeneous. For instance, hydrogen also has one valence electron and is in the same group as the alkali metals, but its chemical behaviour is quite different. The stable elements of <a href="/wiki/Carbon_group" title="Carbon group">group 14</a> comprise a nonmetal (<a href="/wiki/Carbon" title="Carbon">carbon</a>), two semiconductors (<a href="/wiki/Silicon" title="Silicon">silicon</a> and <a href="/wiki/Germanium" title="Germanium">germanium</a>), and two metals (<a href="/wiki/Tin" title="Tin">tin</a> and <a href="/wiki/Lead" title="Lead">lead</a>); they are nonetheless united by having four valence electrons.<sup id="cite_ref-Scerri14_156-0" class="reference"><a href="#cite_note-Scerri14-156"><span class="cite-bracket">[</span>143<span class="cite-bracket">]</span></a></sup> This often leads to similarities in maximum and minimum oxidation states (e.g. <a href="/wiki/Sulfur" title="Sulfur">sulfur</a> and <a href="/wiki/Selenium" title="Selenium">selenium</a> in <a href="/wiki/Chalcogen" title="Chalcogen">group 16</a> both have maximum oxidation state +6, as in <a href="/wiki/Sulfur_trioxide" title="Sulfur trioxide">SO<sub>3</sub></a> and <a href="/wiki/Selenium_trioxide" title="Selenium trioxide">SeO<sub>3</sub></a>, and minimum oxidation state −2, as in <a href="/wiki/Sulfide" title="Sulfide">sulfides</a> and <a href="/wiki/Selenide" title="Selenide">selenides</a>); but not always (e.g. <a href="/wiki/Oxygen" title="Oxygen">oxygen</a> is not known to form oxidation state +6, despite being in the same group as sulfur and selenium).<sup id="cite_ref-jensenlaw_66-19" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Electronegativity">Electronegativity</h3></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Electrostatic_Potential.jpg" class="mw-file-description"><img alt="A water molecule is put into a see-through egg shape, which is colour-coded by electrostatic potential. A concentration of red is near the top of the shape, where the oxygen atom is, and gradually shifts through yellow, green, and then to blue near the lower-right and lower-left corners of the shape where the hydrogen atoms are." src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d4/Electrostatic_Potential.jpg/330px-Electrostatic_Potential.jpg" decoding="async" width="330" height="83" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/d/d4/Electrostatic_Potential.jpg 1.5x" data-file-width="439" data-file-height="110" /></a><figcaption>Electrostatic potential map of a water molecule, where the oxygen atom has a more negative charge (red) than the positive (blue) hydrogen atoms</figcaption></figure> <p>Another important property of elements is their <a href="/wiki/Electronegativity" title="Electronegativity">electronegativity</a>. Atoms can form <a href="/wiki/Covalent_bond" title="Covalent bond">covalent bonds</a> to each other by sharing electrons in pairs, creating an overlap of valence orbitals. The degree to which each atom attracts the shared electron pair depends on the atom's electronegativity<sup id="cite_ref-Greenwood25_157-0" class="reference"><a href="#cite_note-Greenwood25-157"><span class="cite-bracket">[</span>144<span class="cite-bracket">]</span></a></sup> – the tendency of an atom towards gaining or losing electrons.<sup id="cite_ref-cartoon_36-7" class="reference"><a href="#cite_note-cartoon-36"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> The more electronegative atom will tend to attract the electron pair more, and the less electronegative (or more electropositive) one will attract it less. In extreme cases, the electron can be thought of as having been passed completely from the more electropositive atom to the more electronegative one, though this is a simplification. The bond then binds two ions, one positive (having given up the electron) and one negative (having accepted it), and is termed an <a href="/wiki/Ionic_bond" class="mw-redirect" title="Ionic bond">ionic bond</a>.<sup id="cite_ref-cartoon_36-8" class="reference"><a href="#cite_note-cartoon-36"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> </p><p>Electronegativity depends on how strongly the nucleus can attract an electron pair, and so it exhibits a similar variation to the other properties already discussed: electronegativity tends to fall going up to down, and rise going left to right. The alkali and alkaline earth metals are among the most electropositive elements, while the chalcogens, halogens, and noble gases are among the most electronegative ones.<sup id="cite_ref-Greenwood25_157-1" class="reference"><a href="#cite_note-Greenwood25-157"><span class="cite-bracket">[</span>144<span class="cite-bracket">]</span></a></sup> </p><p>Electronegativity is generally measured on the Pauling scale, on which the most electronegative reactive atom (<a href="/wiki/Fluorine" title="Fluorine">fluorine</a>) is given electronegativity 4.0, and the least electronegative atom (<a href="/wiki/Caesium" title="Caesium">caesium</a>) is given electronegativity 0.79.<sup id="cite_ref-cartoon_36-9" class="reference"><a href="#cite_note-cartoon-36"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> In fact <a href="/wiki/Neon" title="Neon">neon</a> is the most electronegative element, but the Pauling scale cannot measure its electronegativity because it does not form covalent bonds with most elements.<sup id="cite_ref-158" class="reference"><a href="#cite_note-158"><span class="cite-bracket">[</span>145<span class="cite-bracket">]</span></a></sup> </p><p>An element's electronegativity varies with the identity and number of the atoms it is bonded to, as well as how many electrons it has already lost: an atom becomes more electronegative when it has lost more electrons.<sup id="cite_ref-Greenwood25_157-2" class="reference"><a href="#cite_note-Greenwood25-157"><span class="cite-bracket">[</span>144<span class="cite-bracket">]</span></a></sup> This sometimes makes a large difference: lead in the +2 oxidation state has electronegativity 1.87 on the Pauling scale, while lead in the +4 oxidation state has electronegativity 2.33.<sup id="cite_ref-159" class="reference"><a href="#cite_note-159"><span class="cite-bracket">[</span>146<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Metallicity">Metallicity</h3></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Diamond_cubic_animation.gif" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/8/89/Diamond_cubic_animation.gif/220px-Diamond_cubic_animation.gif" decoding="async" width="220" height="166" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/8/89/Diamond_cubic_animation.gif 1.5x" data-file-width="300" data-file-height="226" /></a><figcaption>The diamond-cubic structure, a giant covalent structure adopted by carbon (as diamond), as well as by silicon, germanium, and (grey) tin, all in group 14.<br />(In grey tin, the band gap vanishes and metallization occurs.<sup id="cite_ref-160" class="reference"><a href="#cite_note-160"><span class="cite-bracket">[</span>147<span class="cite-bracket">]</span></a></sup> Tin has another allotrope, white tin, whose structure is even more metallic.)</figcaption></figure> <p>A simple substance is a substance formed from atoms of one chemical element. The simple substances of the more electronegative atoms tend to share electrons (form covalent bonds) with each other. They form either small molecules (like hydrogen or oxygen, whose atoms bond in pairs) or giant structures stretching indefinitely (like carbon or silicon). The noble gases simply stay as single atoms, as they already have a full shell.<sup id="cite_ref-cartoon_36-10" class="reference"><a href="#cite_note-cartoon-36"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> Substances composed of discrete molecules or single atoms are held together by weaker attractive forces between the molecules, such as the <a href="/wiki/London_dispersion_force" title="London dispersion force">London dispersion force</a>: as electrons move within the molecules, they create momentary imbalances of electrical charge, which induce similar imbalances on nearby molecules and create synchronized movements of electrons across many neighbouring molecules.<sup id="cite_ref-161" class="reference"><a href="#cite_note-161"><span class="cite-bracket">[</span>148<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Graphite-and-diamond-with-scale.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/f/f0/Graphite-and-diamond-with-scale.jpg/220px-Graphite-and-diamond-with-scale.jpg" decoding="async" width="220" height="129" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/f0/Graphite-and-diamond-with-scale.jpg/330px-Graphite-and-diamond-with-scale.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/f0/Graphite-and-diamond-with-scale.jpg/440px-Graphite-and-diamond-with-scale.jpg 2x" data-file-width="961" data-file-height="562" /></a><figcaption>Graphite and diamond, two allotropes of carbon</figcaption></figure> <p>The more electropositive atoms, however, tend to instead lose electrons, creating a "sea" of electrons engulfing cations.<sup id="cite_ref-cartoon_36-11" class="reference"><a href="#cite_note-cartoon-36"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> The outer orbitals of one atom overlap to share electrons with all its neighbours, creating a giant structure of molecular orbitals extending over all the atoms.<sup id="cite_ref-chemguidemetal_162-0" class="reference"><a href="#cite_note-chemguidemetal-162"><span class="cite-bracket">[</span>149<span class="cite-bracket">]</span></a></sup> This negatively charged "sea" pulls on all the ions and keeps them together in a <a href="/wiki/Metallic_bond" class="mw-redirect" title="Metallic bond">metallic bond</a>. Elements forming such bonds are often called <a href="/wiki/Metal" title="Metal">metals</a>; those which do not are often called <a href="/wiki/Nonmetal_(chemistry)" class="mw-redirect" title="Nonmetal (chemistry)">nonmetals</a>.<sup id="cite_ref-cartoon_36-12" class="reference"><a href="#cite_note-cartoon-36"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> Some elements can form multiple simple substances with different structures: these are called <a href="/wiki/Allotrope" class="mw-redirect" title="Allotrope">allotropes</a>. For example, <a href="/wiki/Diamond" title="Diamond">diamond</a> and <a href="/wiki/Graphite" title="Graphite">graphite</a> are two allotropes of carbon.<sup id="cite_ref-Scerri14_156-1" class="reference"><a href="#cite_note-Scerri14-156"><span class="cite-bracket">[</span>143<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-164" class="reference"><a href="#cite_note-164"><span class="cite-bracket">[</span>n<span class="cite-bracket">]</span></a></sup> </p><p>The metallicity of an element can be predicted from electronic properties. When atomic orbitals overlap during metallic or covalent bonding, they create both bonding and antibonding <a href="/wiki/Molecular_orbital" title="Molecular orbital">molecular orbitals</a> of equal capacity, with the antibonding orbitals of higher energy. Net bonding character occurs when there are more electrons in the bonding orbitals than there are in the antibonding orbitals. Metallic bonding is thus possible when the number of electrons delocalized by each atom is less than twice the number of orbitals contributing to the overlap. This is the situation for elements in groups 1 through 13; they also have too few valence electrons to form giant covalent structures where all atoms take equivalent positions, and so almost all of them metallise. The exceptions are hydrogen and boron, which have too high an ionisation energy. Hydrogen thus forms a covalent H<sub>2</sub> molecule, and boron forms a giant covalent structure based on icosahedral B<sub>12</sub> clusters. In a metal, the bonding and antibonding orbitals have overlapping energies, creating a single band that electrons can freely flow through, allowing for electrical conduction.<sup id="cite_ref-Siekierski_165-0" class="reference"><a href="#cite_note-Siekierski-165"><span class="cite-bracket">[</span>151<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Solid_state_electronic_band_structure.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/ef/Solid_state_electronic_band_structure.svg/440px-Solid_state_electronic_band_structure.svg.png" decoding="async" width="440" height="201" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/ef/Solid_state_electronic_band_structure.svg/660px-Solid_state_electronic_band_structure.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/ef/Solid_state_electronic_band_structure.svg/880px-Solid_state_electronic_band_structure.svg.png 2x" data-file-width="388" data-file-height="177" /></a><figcaption>Graph of carbon atoms being brought together to form a diamond crystal, demonstrating formation of the electronic band structure and band gap. The right graph shows the energy levels as a function of the spacing between atoms. When far apart <i>(right side of graph)</i> all the atoms have discrete valence orbitals <i>p</i> and <i>s</i> with the same energies. However, when the atoms come closer <i>(left side)</i>, their electron orbitals begin to spatially overlap. The <a href="/wiki/Pauli_exclusion_principle" title="Pauli exclusion principle">Pauli exclusion principle</a> prohibits them from having the same energy, so the orbitals hybridize into <i>N</i> molecular orbitals each with a different energy, where <i>N</i> is the number of atoms in the crystal. Since <i>N</i> is such a large number, adjacent orbitals are extremely close together in energy so the orbitals can be considered a continuous energy band. At the actual diamond crystal cell size (denoted by <i>a</i>), two bands are formed, called the valence and conduction bands, separated by a 5.5 <a href="/wiki/Electronvolt" title="Electronvolt">eV</a> band gap. (Here only the valence 2s and 2p electrons have been illustrated; the 1s orbitals do not significantly overlap, so the bands formed from them are much narrower.)</figcaption></figure> <p>In group 14, both metallic and covalent bonding become possible. In a diamond crystal, covalent bonds between carbon atoms are strong, because they have a small atomic radius and thus the nucleus has more of a hold on the electrons. Therefore, the bonding orbitals that result are much lower in energy than the antibonding orbitals, and there is no overlap, so electrical conduction becomes impossible: carbon is a nonmetal. However, covalent bonding becomes weaker for larger atoms and the energy gap between the bonding and antibonding orbitals decreases. Therefore, silicon and germanium have smaller <a href="/wiki/Band_gap" title="Band gap">band gaps</a> and are <a href="/wiki/Semiconductor" title="Semiconductor">semiconductors</a> at ambient conditions: electrons can cross the gap when thermally excited. (Boron is also a semiconductor at ambient conditions.) The band gap disappears in tin, so that tin and lead become metals.<sup id="cite_ref-Siekierski_165-1" class="reference"><a href="#cite_note-Siekierski-165"><span class="cite-bracket">[</span>151<span class="cite-bracket">]</span></a></sup> As the temperature rises, all nonmetals develop some semiconducting properties, to a greater or lesser extent depending on the size of the band gap. Thus metals and nonmetals may be distinguished by the temperature dependence of their electrical conductivity: a metal's conductivity lowers as temperature rises (because thermal motion makes it more difficult for the electrons to flow freely), whereas a nonmetal's conductivity rises (as more electrons may be excited to cross the gap).<sup id="cite_ref-steudel_166-0" class="reference"><a href="#cite_note-steudel-166"><span class="cite-bracket">[</span>152<span class="cite-bracket">]</span></a></sup> </p><p>Elements in groups 15 through 17 have too many electrons to form giant covalent molecules that stretch in all three dimensions. For the lighter elements, the bonds in small diatomic molecules are so strong that a condensed phase is disfavoured: thus nitrogen (N<sub>2</sub>), oxygen (O<sub>2</sub>), white phosphorus and yellow arsenic (P<sub>4</sub> and As<sub>4</sub>), sulfur and red selenium (S<sub>8</sub> and Se<sub>8</sub>), and the stable halogens (F<sub>2</sub>, Cl<sub>2</sub>, Br<sub>2</sub>, and I<sub>2</sub>) readily form covalent molecules with few atoms. The heavier ones tend to form long chains (e.g. red phosphorus, grey selenium, tellurium) or layered structures (e.g. carbon as graphite, black phosphorus, grey arsenic, antimony, bismuth) that only extend in one or two rather than three dimensions. Both kinds of structures can be found as allotropes of phosphorus, arsenic, and selenium, although the long-chained allotropes are more stable in all three. As these structures do not use all their orbitals for bonding, they end up with bonding, nonbonding, and antibonding bands in order of increasing energy. Similarly to group 14, the band gaps shrink for the heavier elements and free movement of electrons between the chains or layers becomes possible. Thus for example black phosphorus, black arsenic, grey selenium, tellurium, and iodine are semiconductors; grey arsenic, antimony, and bismuth are <a href="/wiki/Semimetal" title="Semimetal">semimetals</a> (exhibiting quasi-metallic conduction, with a very small band overlap); and polonium and probably astatine are true metals.<sup id="cite_ref-Siekierski_165-2" class="reference"><a href="#cite_note-Siekierski-165"><span class="cite-bracket">[</span>151<span class="cite-bracket">]</span></a></sup> Finally, the natural group 18 elements all stay as individual atoms.<sup id="cite_ref-Siekierski_165-3" class="reference"><a href="#cite_note-Siekierski-165"><span class="cite-bracket">[</span>151<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-168" class="reference"><a href="#cite_note-168"><span class="cite-bracket">[</span>o<span class="cite-bracket">]</span></a></sup> </p><p>The dividing line between metals and nonmetals is roughly diagonal from top left to bottom right, with the transition series appearing to the left of this diagonal (as they have many available orbitals for overlap). This is expected, as metallicity tends to be correlated with electropositivity and the willingness to lose electrons, which increases right to left and up to down. Thus the metals greatly outnumber the nonmetals. Elements near the borderline are difficult to classify: they tend to have properties that are intermediate between those of metals and nonmetals, and may have some properties characteristic of both. They are often termed semimetals or <a href="/wiki/Metalloid" title="Metalloid">metalloids</a>.<sup id="cite_ref-cartoon_36-13" class="reference"><a href="#cite_note-cartoon-36"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> The term "semimetal" used in this sense should not be confused with its strict physical sense having to do with band structure: bismuth is physically a semimetal, but is generally considered a metal by chemists.<sup id="cite_ref-169" class="reference"><a href="#cite_note-169"><span class="cite-bracket">[</span>154<span class="cite-bracket">]</span></a></sup> </p><p>The following table considers the most stable allotropes at standard conditions. The elements coloured yellow form simple substances that are well-characterised by metallic bonding. Elements coloured light blue form giant network covalent structures, whereas those coloured dark blue form small covalently bonded molecules that are held together by weaker <a href="/wiki/Van_der_Waals_force" title="Van der Waals force">van der Waals forces</a>. The noble gases are coloured in violet: their molecules are single atoms and no covalent bonding occurs. Greyed-out cells are for elements which have not been prepared in sufficient quantities for their most stable allotropes to have been characterized in this way. Theoretical considerations and current experimental evidence suggest that all of those elements would metallise if they could form condensed phases,<sup id="cite_ref-Siekierski_165-5" class="reference"><a href="#cite_note-Siekierski-165"><span class="cite-bracket">[</span>151<span class="cite-bracket">]</span></a></sup> except perhaps for oganesson.<sup id="cite_ref-semiconductor_170-0" class="reference"><a href="#cite_note-semiconductor-170"><span class="cite-bracket">[</span>155<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-180" class="reference"><a href="#cite_note-180"><span class="cite-bracket">[</span>p<span class="cite-bracket">]</span></a></sup> </p> <table class="collapsible uncollapsed" border="0" cellpadding="0" cellspacing="1" style="table-layout:fixed; background:#f8f8f8; border:1px solid #a9a9a9; width:100%; max-width:1300px; margin:0 auto; padding:2px; ;"> <tbody><tr> <th colspan="33" style="background:#d8d8d8; padding:2px 4px;"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-collapse navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Periodic_table_(simple_substance_bonding)" title="Template:Periodic table (simple substance bonding)"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Periodic_table_(simple_substance_bonding)" title="Template talk:Periodic table (simple substance bonding)"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Periodic_table_(simple_substance_bonding)" title="Special:EditPage/Template:Periodic table (simple substance bonding)"><abbr title="Edit this template">e</abbr></a></li></ul></div><div class="navbar-ct-mini">Bonding of simple substances in the periodic table</div> </th></tr> <tr style="background:#e8e8e8"> <th> </th> <th><a href="/wiki/Alkali_metal" title="Alkali metal">1</a> </th> <th><a href="/wiki/Alkaline_earth_metal" title="Alkaline earth metal">2</a> </th> <th colspan="14"> </th> <th><a href="/wiki/Group_3_element" title="Group 3 element">3</a> </th> <th><a href="/wiki/Group_4_element" title="Group 4 element">4</a> </th> <th><a href="/wiki/Group_5_element" title="Group 5 element">5</a> </th> <th><a href="/wiki/Group_6_element" title="Group 6 element">6</a> </th> <th><a href="/wiki/Group_7_element" title="Group 7 element">7</a> </th> <th><a href="/wiki/Group_8_element" title="Group 8 element">8</a> </th> <th><a href="/wiki/Group_9_element" title="Group 9 element">9</a> </th> <th><a href="/wiki/Group_10_element" title="Group 10 element">10</a> </th> <th><a href="/wiki/Group_11_element" title="Group 11 element">11</a> </th> <th><a href="/wiki/Group_12_element" title="Group 12 element">12</a> </th> <th><a href="/wiki/Boron_group" title="Boron group">13</a> </th> <th><a href="/wiki/Carbon_group" title="Carbon group">14</a> </th> <th><a href="/wiki/Pnictogen" title="Pnictogen">15</a> </th> <th><a href="/wiki/Chalcogen" title="Chalcogen">16</a> </th> <th><a href="/wiki/Halogen" title="Halogen">17</a> </th> <th><a href="/wiki/Noble_gas" title="Noble gas">18</a> </th></tr> <tr> <th colspan="3" style="text-align:left; font-size:90%; line-height:110%;"><a href="/wiki/Periodic_table_group" class="mw-redirect" title="Periodic table group">Group</a> → </th></tr> <tr> <th colspan="3" style="text-align:left; font-size:90%; line-height:110%;">↓ <a href="/wiki/Periodic_table_period" class="mw-redirect" title="Periodic table period">Period</a> </th></tr> <tr> <th><a href="/wiki/Period_1_element" title="Period 1 element">1</a> </th> <td title="H , hydrogen" style="text-align:center; color:#000000; background-color:#b0c0e6; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Hydrogen" title="Hydrogen"><span style="display:block">H</span></a></span> </td> <td colspan="30"> </td> <td title="He, helium" style="text-align:center; color:#000000; background-color:#e0b0e6; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Helium" title="Helium"><span style="display:block">He</span></a></span> </td></tr> <tr> <th><a href="/wiki/Period_2_element" title="Period 2 element">2</a> </th> <td title="Li, lithium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Lithium" title="Lithium"><span style="display:block">Li</span></a></span> </td> <td title="Be, beryllium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Beryllium" title="Beryllium"><span style="display:block">Be</span></a></span> </td> <td colspan="24"> </td> <td title="B , boron" style="text-align:center; color:#000000; background-color:#b0e0e6; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Boron" title="Boron"><span style="display:block">B</span></a></span> </td> <td title="C , carbon" style="text-align:center; color:#000000; background-color:#b0e0e6; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Carbon" title="Carbon"><span style="display:block">C</span></a></span> </td> <td title="N , nitrogen" style="text-align:center; color:#000000; background-color:#b0c0e6; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Nitrogen" title="Nitrogen"><span style="display:block">N</span></a></span> </td> <td title="O , oxygen" style="text-align:center; color:#000000; background-color:#b0c0e6; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Oxygen" title="Oxygen"><span style="display:block">O</span></a></span> </td> <td title="F , fluorine" style="text-align:center; color:#000000; background-color:#b0c0e6; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Fluorine" title="Fluorine"><span style="display:block">F</span></a></span> </td> <td title="Ne, neon" style="text-align:center; color:#000000; background-color:#e0b0e6; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Neon" title="Neon"><span style="display:block">Ne</span></a></span> </td></tr> <tr> <th><a href="/wiki/Period_3_element" title="Period 3 element">3</a> </th> <td title="Na, sodium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Sodium" title="Sodium"><span style="display:block">Na</span></a></span> </td> <td title="Mg, magnesium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Magnesium" title="Magnesium"><span style="display:block">Mg</span></a></span> </td> <td colspan="24"> </td> <td title="Al, aluminium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Aluminium" title="Aluminium"><span style="display:block">Al</span></a></span> </td> <td title="Si, silicon" style="text-align:center; color:#000000; background-color:#b0e0e6; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Silicon" title="Silicon"><span style="display:block">Si</span></a></span> </td> <td title="P , phosphorus" style="text-align:center; color:#000000; background-color:#b0e0e6; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Phosphorus" title="Phosphorus"><span style="display:block">P</span></a></span> </td> <td title="S , sulfur" style="text-align:center; color:#000000; background-color:#b0c0e6; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Sulfur" title="Sulfur"><span style="display:block">S</span></a></span> </td> <td title="Cl, chlorine" style="text-align:center; color:#000000; background-color:#b0c0e6; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Chlorine" title="Chlorine"><span style="display:block">Cl</span></a></span> </td> <td title="Ar, argon" style="text-align:center; color:#000000; background-color:#e0b0e6; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Argon" title="Argon"><span style="display:block">Ar</span></a></span> </td></tr> <tr> <th><a href="/wiki/Period_4_element" title="Period 4 element">4</a> </th> <td title="K , potassium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Potassium" title="Potassium"><span style="display:block">K</span></a></span> </td> <td title="Ca, calcium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Calcium" title="Calcium"><span style="display:block">Ca</span></a></span> </td> <td colspan="14"> </td> <td title="Sc, scandium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Scandium" title="Scandium"><span style="display:block">Sc</span></a></span> </td> <td title="Ti, titanium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Titanium" title="Titanium"><span style="display:block">Ti</span></a></span> </td> <td title="V , vanadium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Vanadium" title="Vanadium"><span style="display:block">V</span></a></span> </td> <td title="Cr, chromium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Chromium" title="Chromium"><span style="display:block">Cr</span></a></span> </td> <td title="Mn, manganese" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Manganese" title="Manganese"><span style="display:block">Mn</span></a></span> </td> <td title="Fe, iron" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Iron" title="Iron"><span style="display:block">Fe</span></a></span> </td> <td title="Co, cobalt" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Cobalt" title="Cobalt"><span style="display:block">Co</span></a></span> </td> <td title="Ni, nickel" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Nickel" title="Nickel"><span style="display:block">Ni</span></a></span> </td> <td title="Cu, copper" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Copper" title="Copper"><span style="display:block">Cu</span></a></span> </td> <td title="Zn, zinc" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Zinc" title="Zinc"><span style="display:block">Zn</span></a></span> </td> <td title="Ga, gallium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Gallium" title="Gallium"><span style="display:block">Ga</span></a></span> </td> <td title="Ge, germanium" style="text-align:center; color:#000000; background-color:#b0e0e6; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Germanium" title="Germanium"><span style="display:block">Ge</span></a></span> </td> <td title="As, arsenic" style="text-align:center; color:#000000; background-color:#b0e0e6; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Arsenic" title="Arsenic"><span style="display:block">As</span></a></span> </td> <td title="Se, selenium" style="text-align:center; color:#000000; background-color:#b0e0e6; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Selenium" title="Selenium"><span style="display:block">Se</span></a></span> </td> <td title="Br, bromine" style="text-align:center; color:#000000; background-color:#b0c0e6; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Bromine" title="Bromine"><span style="display:block">Br</span></a></span> </td> <td title="Kr, krypton" style="text-align:center; color:#000000; background-color:#e0b0e6; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Krypton" title="Krypton"><span style="display:block">Kr</span></a></span> </td></tr> <tr> <th><a href="/wiki/Period_5_element" title="Period 5 element">5</a> </th> <td title="Rb, rubidium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Rubidium" title="Rubidium"><span style="display:block">Rb</span></a></span> </td> <td title="Sr, strontium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Strontium" title="Strontium"><span style="display:block">Sr</span></a></span> </td> <td colspan="14"> </td> <td title="Y , yttrium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Yttrium" title="Yttrium"><span style="display:block">Y</span></a></span> </td> <td title="Zr, zirconium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Zirconium" title="Zirconium"><span style="display:block">Zr</span></a></span> </td> <td title="Nb, niobium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Niobium" title="Niobium"><span style="display:block">Nb</span></a></span> </td> <td title="Mo, molybdenum" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Molybdenum" title="Molybdenum"><span style="display:block">Mo</span></a></span> </td> <td title="Tc, technetium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px dashed #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Technetium" title="Technetium"><span style="display:block">Tc</span></a></span> </td> <td title="Ru, ruthenium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Ruthenium" title="Ruthenium"><span style="display:block">Ru</span></a></span> </td> <td title="Rh, rhodium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Rhodium" title="Rhodium"><span style="display:block">Rh</span></a></span> </td> <td title="Pd, palladium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Palladium" title="Palladium"><span style="display:block">Pd</span></a></span> </td> <td title="Ag, silver" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Silver" title="Silver"><span style="display:block">Ag</span></a></span> </td> <td title="Cd, cadmium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Cadmium" title="Cadmium"><span style="display:block">Cd</span></a></span> </td> <td title="In, indium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Indium" title="Indium"><span style="display:block">In</span></a></span> </td> <td title="Sn, tin" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Tin" title="Tin"><span style="display:block">Sn</span></a></span> </td> <td title="Sb, antimony" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Antimony" title="Antimony"><span style="display:block">Sb</span></a></span> </td> <td title="Te, tellurium" style="text-align:center; color:#000000; background-color:#b0e0e6; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Tellurium" title="Tellurium"><span style="display:block">Te</span></a></span> </td> <td title="I , iodine" style="text-align:center; color:#000000; background-color:#b0c0e6; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Iodine" title="Iodine"><span style="display:block">I</span></a></span> </td> <td title="Xe, xenon" style="text-align:center; color:#000000; background-color:#e0b0e6; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Xenon" title="Xenon"><span style="display:block">Xe</span></a></span> </td></tr> <tr> <th><a href="/wiki/Period_6_element" title="Period 6 element">6</a> </th> <td title="Cs, caesium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Caesium" title="Caesium"><span style="display:block">Cs</span></a></span> </td> <td title="Ba, barium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Barium" title="Barium"><span style="display:block">Ba</span></a></span> </td> <td title="La, lanthanum" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Lanthanum" title="Lanthanum"><span style="display:block">La</span></a></span> </td> <td title="Ce, cerium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Cerium" title="Cerium"><span style="display:block">Ce</span></a></span> </td> <td title="Pr, praseodymium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Praseodymium" title="Praseodymium"><span style="display:block">Pr</span></a></span> </td> <td title="Nd, neodymium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Neodymium" title="Neodymium"><span style="display:block">Nd</span></a></span> </td> <td title="Pm, promethium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px dashed #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Promethium" title="Promethium"><span style="display:block">Pm</span></a></span> </td> <td title="Sm, samarium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Samarium" title="Samarium"><span style="display:block">Sm</span></a></span> </td> <td title="Eu, europium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Europium" title="Europium"><span style="display:block">Eu</span></a></span> </td> <td title="Gd, gadolinium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Gadolinium" title="Gadolinium"><span style="display:block">Gd</span></a></span> </td> <td title="Tb, terbium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Terbium" title="Terbium"><span style="display:block">Tb</span></a></span> </td> <td title="Dy, dysprosium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Dysprosium" title="Dysprosium"><span style="display:block">Dy</span></a></span> </td> <td title="Ho, holmium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Holmium" title="Holmium"><span style="display:block">Ho</span></a></span> </td> <td title="Er, erbium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Erbium" title="Erbium"><span style="display:block">Er</span></a></span> </td> <td title="Tm, thulium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Thulium" title="Thulium"><span style="display:block">Tm</span></a></span> </td> <td title="Yb, ytterbium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Ytterbium" title="Ytterbium"><span style="display:block">Yb</span></a></span> </td> <td title="Lu, lutetium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Lutetium" title="Lutetium"><span style="display:block">Lu</span></a></span> </td> <td title="Hf, hafnium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Hafnium" title="Hafnium"><span style="display:block">Hf</span></a></span> </td> <td title="Ta, tantalum" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Tantalum" title="Tantalum"><span style="display:block">Ta</span></a></span> </td> <td title="W , tungsten" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Tungsten" title="Tungsten"><span style="display:block">W</span></a></span> </td> <td title="Re, rhenium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Rhenium" title="Rhenium"><span style="display:block">Re</span></a></span> </td> <td title="Os, osmium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Osmium" title="Osmium"><span style="display:block">Os</span></a></span> </td> <td title="Ir, iridium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Iridium" title="Iridium"><span style="display:block">Ir</span></a></span> </td> <td title="Pt, platinum" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Platinum" title="Platinum"><span style="display:block">Pt</span></a></span> </td> <td title="Au, gold" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Gold" title="Gold"><span style="display:block">Au</span></a></span> </td> <td title="Hg, mercury" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Mercury_(element)" title="Mercury (element)"><span style="display:block">Hg</span></a></span> </td> <td title="Tl, thallium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Thallium" title="Thallium"><span style="display:block">Tl</span></a></span> </td> <td title="Pb, lead" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Lead" title="Lead"><span style="display:block">Pb</span></a></span> </td> <td title="Bi, bismuth" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Bismuth" title="Bismuth"><span style="display:block">Bi</span></a></span> </td> <td title="Po, polonium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px dashed #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Polonium" title="Polonium"><span style="display:block">Po</span></a></span> </td> <td title="At, astatine" style="text-align:center; color:#000000; background-color:#e8e8e8; border:2px dashed #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Astatine" title="Astatine"><span style="display:block">At</span></a></span> </td> <td title="Rn, radon" style="text-align:center; color:#000000; background-color:#e0b0e6; border:2px dashed #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Radon" title="Radon"><span style="display:block">Rn</span></a></span> </td></tr> <tr> <th><a href="/wiki/Period_7_element" title="Period 7 element">7</a> </th> <td title="Fr, francium" style="text-align:center; color:#000000; background-color:#e8e8e8; border:2px dashed #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Francium" title="Francium"><span style="display:block">Fr</span></a></span> </td> <td title="Ra, radium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px dashed #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Radium" title="Radium"><span style="display:block">Ra</span></a></span> </td> <td title="Ac, actinium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px dashed #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Actinium" title="Actinium"><span style="display:block">Ac</span></a></span> </td> <td title="Th, thorium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Thorium" title="Thorium"><span style="display:block">Th</span></a></span> </td> <td title="Pa, protactinium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px dashed #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Protactinium" title="Protactinium"><span style="display:block">Pa</span></a></span> </td> <td title="U , uranium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px solid #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Uranium" title="Uranium"><span style="display:block">U</span></a></span> </td> <td title="Np, neptunium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px dashed #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Neptunium" title="Neptunium"><span style="display:block">Np</span></a></span> </td> <td title="Pu, plutonium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px dashed #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Plutonium" title="Plutonium"><span style="display:block">Pu</span></a></span> </td> <td title="Am, americium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Americium" title="Americium"><span style="display:block">Am</span></a></span> </td> <td title="Cm, curium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Curium" title="Curium"><span style="display:block">Cm</span></a></span> </td> <td title="Bk, berkelium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Berkelium" title="Berkelium"><span style="display:block">Bk</span></a></span> </td> <td title="Cf, californium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Californium" title="Californium"><span style="display:block">Cf</span></a></span> </td> <td title="Es, einsteinium" style="text-align:center; color:#000000; background-color:#eee8aa; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Einsteinium" title="Einsteinium"><span style="display:block">Es</span></a></span> </td> <td title="Fm, fermium" style="text-align:center; color:#000000; background-color:#e8e8e8; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Fermium" title="Fermium"><span style="display:block">Fm</span></a></span> </td> <td title="Md, mendelevium" style="text-align:center; color:#000000; background-color:#e8e8e8; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Mendelevium" title="Mendelevium"><span style="display:block">Md</span></a></span> </td> <td title="No, nobelium" style="text-align:center; color:#000000; background-color:#e8e8e8; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Nobelium" title="Nobelium"><span style="display:block">No</span></a></span> </td> <td title="Lr, lawrencium" style="text-align:center; color:#000000; background-color:#e8e8e8; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Lawrencium" title="Lawrencium"><span style="display:block">Lr</span></a></span> </td> <td title="Rf, rutherfordium" style="text-align:center; color:#000000; background-color:#e8e8e8; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Rutherfordium" title="Rutherfordium"><span style="display:block">Rf</span></a></span> </td> <td title="Db, dubnium" style="text-align:center; color:#000000; background-color:#e8e8e8; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Dubnium" title="Dubnium"><span style="display:block">Db</span></a></span> </td> <td title="Sg, seaborgium" style="text-align:center; color:#000000; background-color:#e8e8e8; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Seaborgium" title="Seaborgium"><span style="display:block">Sg</span></a></span> </td> <td title="Bh, bohrium" style="text-align:center; color:#000000; background-color:#e8e8e8; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Bohrium" title="Bohrium"><span style="display:block">Bh</span></a></span> </td> <td title="Hs, hassium" style="text-align:center; color:#000000; background-color:#e8e8e8; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Hassium" title="Hassium"><span style="display:block">Hs</span></a></span> </td> <td title="Mt, meitnerium" style="text-align:center; color:#000000; background-color:#e8e8e8; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Meitnerium" title="Meitnerium"><span style="display:block">Mt</span></a></span> </td> <td title="Ds, darmstadtium" style="text-align:center; color:#000000; background-color:#e8e8e8; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Darmstadtium" title="Darmstadtium"><span style="display:block">Ds</span></a></span> </td> <td title="Rg, roentgenium" style="text-align:center; color:#000000; background-color:#e8e8e8; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Roentgenium" title="Roentgenium"><span style="display:block">Rg</span></a></span> </td> <td title="Cn, copernicium" style="text-align:center; color:#000000; background-color:#e8e8e8; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Copernicium" title="Copernicium"><span style="display:block">Cn</span></a></span> </td> <td title="Nh, nihonium" style="text-align:center; color:#000000; background-color:#e8e8e8; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Nihonium" title="Nihonium"><span style="display:block">Nh</span></a></span> </td> <td title="Fl, flerovium" style="text-align:center; color:#000000; background-color:#e8e8e8; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Flerovium" title="Flerovium"><span style="display:block">Fl</span></a></span> </td> <td title="Mc, moscovium" style="text-align:center; color:#000000; background-color:#e8e8e8; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Moscovium" title="Moscovium"><span style="display:block">Mc</span></a></span> </td> <td title="Lv, livermorium" style="text-align:center; color:#000000; background-color:#e8e8e8; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Livermorium" title="Livermorium"><span style="display:block">Lv</span></a></span> </td> <td title="Ts, tennessine" style="text-align:center; color:#000000; background-color:#e8e8e8; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Tennessine" title="Tennessine"><span style="display:block">Ts</span></a></span> </td> <td title="Og, oganesson" style="text-align:center; color:#000000; background-color:#e8e8e8; border:2px dotted #6e6e8e; ;"><span class="nowrap"><a href="/wiki/Oganesson" title="Oganesson"><span style="display:block">Og</span></a></span> </td></tr> <tr> <td style="line-height:50%;"><br /> </td></tr></tbody></table> <div role="presentation" id="periodic-table-legend" style="border: 1px solid #a2a9b1; width:100%; line-height:120%; text-align:center; vertical-align:top; background:#f8f8f8; margin:0;"><div style="padding:0.3em;"> <p><span style="display: inline-block;"> <span style="display: inline-block; width:*; background:#eee8aa"><a href="/wiki/Metallic_bonding" title="Metallic bonding">Metallic</a></span> <span style="display: inline-block; width:*; background:#b0e0e6"><a href="/wiki/Network_covalent_bonding" title="Network covalent bonding">Network covalent</a></span> <span style="display: inline-block; width:*; background:#b0c0e6">Molecular <a href="/wiki/Covalent_bond" title="Covalent bond">covalent</a></span> <span style="display: inline-block; width:*; background:#e0b0e6">Single atoms</span> <span style="display: inline-block; width:*; padding:0 0.5em; background:#e8e8e8">Unknown</span> </span><span style="display: inline-block;"><b>Background color</b> shows bonding of simple substances in the <a class="mw-selflink selflink">periodic table</a>. If there are several, the most stable allotrope is considered.</span> </p> </div> </div> <ul class="gallery mw-gallery-packed"> <li class="gallerybox" style="width: 194.66666666667px"> <div class="thumb" style="width: 192.66666666667px;"><span typeof="mw:File"><a href="/wiki/File:Iron_electrolytic_and_1cm3_cube.jpg" class="mw-file-description" title="Iron, a metal"><img alt="Iron, a metal" src="//upload.wikimedia.org/wikipedia/commons/thumb/a/ad/Iron_electrolytic_and_1cm3_cube.jpg/289px-Iron_electrolytic_and_1cm3_cube.jpg" decoding="async" width="193" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/ad/Iron_electrolytic_and_1cm3_cube.jpg/434px-Iron_electrolytic_and_1cm3_cube.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/ad/Iron_electrolytic_and_1cm3_cube.jpg/579px-Iron_electrolytic_and_1cm3_cube.jpg 2x" data-file-width="5135" data-file-height="3197" /></a></span></div> <div class="gallerytext">Iron, a metal</div> </li> <li class="gallerybox" style="width: 146px"> <div class="thumb" style="width: 144px;"><span typeof="mw:File"><a href="/wiki/File:Sulfur_-_El_Desierto_mine,_San_Pablo_de_Napa,_Daniel_Campos_Province,_Potos%C3%AD,_Bolivia.jpg" class="mw-file-description" title="Sulfur, a nonmetal"><img alt="Sulfur, a nonmetal" src="//upload.wikimedia.org/wikipedia/commons/thumb/8/88/Sulfur_-_El_Desierto_mine%2C_San_Pablo_de_Napa%2C_Daniel_Campos_Province%2C_Potos%C3%AD%2C_Bolivia.jpg/216px-Sulfur_-_El_Desierto_mine%2C_San_Pablo_de_Napa%2C_Daniel_Campos_Province%2C_Potos%C3%AD%2C_Bolivia.jpg" decoding="async" width="144" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/88/Sulfur_-_El_Desierto_mine%2C_San_Pablo_de_Napa%2C_Daniel_Campos_Province%2C_Potos%C3%AD%2C_Bolivia.jpg/324px-Sulfur_-_El_Desierto_mine%2C_San_Pablo_de_Napa%2C_Daniel_Campos_Province%2C_Potos%C3%AD%2C_Bolivia.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/88/Sulfur_-_El_Desierto_mine%2C_San_Pablo_de_Napa%2C_Daniel_Campos_Province%2C_Potos%C3%AD%2C_Bolivia.jpg/432px-Sulfur_-_El_Desierto_mine%2C_San_Pablo_de_Napa%2C_Daniel_Campos_Province%2C_Potos%C3%AD%2C_Bolivia.jpg 2x" data-file-width="6000" data-file-height="5000" /></a></span></div> <div class="gallerytext">Sulfur, a nonmetal</div> </li> <li class="gallerybox" style="width: 211.33333333333px"> <div class="thumb" style="width: 209.33333333333px;"><span typeof="mw:File"><a href="/wiki/File:Arsen_1a.jpg" class="mw-file-description" title="Arsenic, an element often called a semi-metal or metalloid"><img alt="Arsenic, an element often called a semi-metal or metalloid" src="//upload.wikimedia.org/wikipedia/commons/thumb/7/7b/Arsen_1a.jpg/314px-Arsen_1a.jpg" decoding="async" width="210" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/7/7b/Arsen_1a.jpg 1.5x" data-file-width="445" data-file-height="255" /></a></span></div> <div class="gallerytext">Arsenic, an element often called a semi-metal or metalloid</div> </li> </ul> <p>Generally, metals are shiny and dense.<sup id="cite_ref-cartoon_36-14" class="reference"><a href="#cite_note-cartoon-36"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> They usually have high melting and boiling points due to the strength of the metallic bond, and are often malleable and ductile (easily stretched and shaped) because the atoms can move relative to each other without breaking the metallic bond.<sup id="cite_ref-chemguidem_181-0" class="reference"><a href="#cite_note-chemguidem-181"><span class="cite-bracket">[</span>165<span class="cite-bracket">]</span></a></sup> They conduct electricity because their electrons are free to move in all three dimensions. Similarly, they conduct heat, which is transferred by the electrons as extra <a href="/wiki/Kinetic_energy" title="Kinetic energy">kinetic energy</a>: they move faster. These properties persist in the liquid state, as although the crystal structure is destroyed on melting, the atoms still touch and the metallic bond persists, though it is weakened.<sup id="cite_ref-chemguidem_181-1" class="reference"><a href="#cite_note-chemguidem-181"><span class="cite-bracket">[</span>165<span class="cite-bracket">]</span></a></sup> Metals tend to be reactive towards nonmetals.<sup id="cite_ref-cartoon_36-15" class="reference"><a href="#cite_note-cartoon-36"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> Some exceptions can be found to these generalizations: for example, beryllium, chromium,<sup id="cite_ref-raynercanham_94-2" class="reference"><a href="#cite_note-raynercanham-94"><span class="cite-bracket">[</span>84<span class="cite-bracket">]</span></a></sup> manganese,<sup id="cite_ref-Holl_182-0" class="reference"><a href="#cite_note-Holl-182"><span class="cite-bracket">[</span>166<span class="cite-bracket">]</span></a></sup> antimony,<sup id="cite_ref-wiberg_holleman_183-0" class="reference"><a href="#cite_note-wiberg_holleman-183"><span class="cite-bracket">[</span>167<span class="cite-bracket">]</span></a></sup> bismuth,<sup id="cite_ref-CRC_184-0" class="reference"><a href="#cite_note-CRC-184"><span class="cite-bracket">[</span>168<span class="cite-bracket">]</span></a></sup> and uranium are brittle (not an exhaustive list);<sup id="cite_ref-raynercanham_94-3" class="reference"><a href="#cite_note-raynercanham-94"><span class="cite-bracket">[</span>84<span class="cite-bracket">]</span></a></sup> chromium is extremely hard;<sup id="cite_ref-r1_185-0" class="reference"><a href="#cite_note-r1-185"><span class="cite-bracket">[</span>169<span class="cite-bracket">]</span></a></sup> gallium, rubidium, caesium, and mercury are liquid at or close to room temperature;<sup id="cite_ref-186" class="reference"><a href="#cite_note-186"><span class="cite-bracket">[</span>q<span class="cite-bracket">]</span></a></sup> and <a href="/wiki/Noble_metal" title="Noble metal">noble metals</a> such as gold are chemically very inert.<sup id="cite_ref-187" class="reference"><a href="#cite_note-187"><span class="cite-bracket">[</span>170<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-188" class="reference"><a href="#cite_note-188"><span class="cite-bracket">[</span>171<span class="cite-bracket">]</span></a></sup> </p><p>Nonmetals exhibit different properties. Those forming giant covalent crystals exhibit high melting and boiling points, as it takes considerable energy to overcome the strong covalent bonds. Those forming discrete molecules are held together mostly by dispersion forces, which are more easily overcome; thus they tend to have lower melting and boiling points,<sup id="cite_ref-189" class="reference"><a href="#cite_note-189"><span class="cite-bracket">[</span>172<span class="cite-bracket">]</span></a></sup> and many are liquids or gases at room temperature.<sup id="cite_ref-cartoon_36-16" class="reference"><a href="#cite_note-cartoon-36"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> Nonmetals are often dull-looking. They tend to be reactive towards metals, except for the noble gases, which are inert towards most substances.<sup id="cite_ref-cartoon_36-17" class="reference"><a href="#cite_note-cartoon-36"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> They are brittle when solid as their atoms are held tightly in place. They are less dense and conduct electricity poorly,<sup id="cite_ref-cartoon_36-18" class="reference"><a href="#cite_note-cartoon-36"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> because there are no mobile electrons.<sup id="cite_ref-group4_190-0" class="reference"><a href="#cite_note-group4-190"><span class="cite-bracket">[</span>173<span class="cite-bracket">]</span></a></sup> Near the borderline, band gaps are small and thus many elements in that region are semiconductors, such as silicon, germanium,<sup id="cite_ref-group4_190-1" class="reference"><a href="#cite_note-group4-190"><span class="cite-bracket">[</span>173<span class="cite-bracket">]</span></a></sup> and tellurium.<sup id="cite_ref-Siekierski_165-6" class="reference"><a href="#cite_note-Siekierski-165"><span class="cite-bracket">[</span>151<span class="cite-bracket">]</span></a></sup> Selenium has both a semiconducting grey allotrope and an insulating red allotrope; arsenic has a metallic grey allotrope, a semiconducting black allotrope, and an insulating yellow allotrope (though the last is unstable at ambient conditions).<sup id="cite_ref-steudel_166-1" class="reference"><a href="#cite_note-steudel-166"><span class="cite-bracket">[</span>152<span class="cite-bracket">]</span></a></sup> Again there are exceptions; for example, diamond has the highest thermal conductivity of all known materials, greater than any metal.<sup id="cite_ref-PNU_191-0" class="reference"><a href="#cite_note-PNU-191"><span class="cite-bracket">[</span>174<span class="cite-bracket">]</span></a></sup> </p><p>It is common to designate a class of metalloids straddling the boundary between metals and nonmetals, as elements in that region are intermediate in both physical and chemical properties.<sup id="cite_ref-cartoon_36-19" class="reference"><a href="#cite_note-cartoon-36"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> However, no consensus exists in the literature for precisely which elements should be so designated. When such a category is used, silicon, germanium, arsenic, and tellurium are almost always included, and boron and antimony usually are; but most sources include other elements as well, without agreement on which extra elements should be added, and some others subtract from this list instead.<sup id="cite_ref-metalloids_196-0" class="reference"><a href="#cite_note-metalloids-196"><span class="cite-bracket">[</span>r<span class="cite-bracket">]</span></a></sup> For example, unlike all the other elements generally considered metalloids or nonmetals, antimony's only stable form has metallic conductivity. Moreover, the element resembles bismuth and, more generally, the other p-block metals in its physical and chemical behaviour. On this basis some authors have argued that it is better classified as a metal than as a metalloid.<sup id="cite_ref-raynercanham_94-4" class="reference"><a href="#cite_note-raynercanham-94"><span class="cite-bracket">[</span>84<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-hawkes_197-0" class="reference"><a href="#cite_note-hawkes-197"><span class="cite-bracket">[</span>179<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-steudel_166-2" class="reference"><a href="#cite_note-steudel-166"><span class="cite-bracket">[</span>152<span class="cite-bracket">]</span></a></sup> On the other hand, selenium has some semiconducting properties in its most stable form (though it also has insulating allotropes) and it has been argued that it should be considered a metalloid<sup id="cite_ref-hawkes_197-1" class="reference"><a href="#cite_note-hawkes-197"><span class="cite-bracket">[</span>179<span class="cite-bracket">]</span></a></sup> – though this situation also holds for phosphorus,<sup id="cite_ref-steudel_166-3" class="reference"><a href="#cite_note-steudel-166"><span class="cite-bracket">[</span>152<span class="cite-bracket">]</span></a></sup> which is a much rarer inclusion among the metalloids.<sup id="cite_ref-metalloids_196-1" class="reference"><a href="#cite_note-metalloids-196"><span class="cite-bracket">[</span>r<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Further_manifestations_of_periodicity">Further manifestations of periodicity</h3></div> <p>There are some other relationships throughout the periodic table between elements that are not in the same group, such as the <a href="/wiki/Diagonal_relationship" title="Diagonal relationship">diagonal relationships</a> between elements that are diagonally adjacent (e.g. lithium and magnesium).<sup id="cite_ref-PTSS2_131-2" class="reference"><a href="#cite_note-PTSS2-131"><span class="cite-bracket">[</span>121<span class="cite-bracket">]</span></a></sup> Some similarities can also be found between the main groups and the transition metal groups, or between the early actinides and early transition metals, when the elements have the same number of valence electrons. Thus uranium somewhat resembles chromium and tungsten in group 6,<sup id="cite_ref-PTSS2_131-3" class="reference"><a href="#cite_note-PTSS2-131"><span class="cite-bracket">[</span>121<span class="cite-bracket">]</span></a></sup> as all three have six valence electrons.<sup id="cite_ref-Jensen_198-0" class="reference"><a href="#cite_note-Jensen-198"><span class="cite-bracket">[</span>180<span class="cite-bracket">]</span></a></sup> Relationships between elements with the same number of valence electrons but different types of valence orbital have been called secondary or isodonor relationships: they usually have the same maximum oxidation states, but not the same minimum oxidation states. For example, chlorine and manganese both have +7 as their maximum oxidation state (e.g. <a href="/wiki/Dichlorine_heptoxide" title="Dichlorine heptoxide">Cl<sub>2</sub>O<sub>7</sub></a> and <a href="/wiki/Manganese_heptoxide" title="Manganese heptoxide">Mn<sub>2</sub>O<sub>7</sub></a>), but their respective minimum oxidation states are −1 (e.g. <a href="/wiki/Hydrogen_chloride" title="Hydrogen chloride">HCl</a>) and −3 (K<sub>2</sub>[Mn(CO)<sub>4</sub>]). Elements with the same number of valence vacancies but different numbers of valence electrons are related by a tertiary or isoacceptor relationship: they usually have similar minimum but not maximum oxidation states. For example, hydrogen and chlorine both have −1 as their minimum oxidation state (in <a href="/wiki/Hydride" title="Hydride">hydrides</a> and <a href="/wiki/Chloride" title="Chloride">chlorides</a>), but hydrogen's maximum oxidation state is +1 (e.g. <a href="/wiki/Water" title="Water">H<sub>2</sub>O</a>) while chlorine's is +7.<sup id="cite_ref-jensenlaw_66-20" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> </p><p>Many other physical properties of the elements exhibit periodic variation in accordance with the periodic law, such as <a href="/wiki/Melting_point" title="Melting point">melting points</a>, <a href="/wiki/Boiling_point" title="Boiling point">boiling points</a>, <a href="/wiki/Heat_of_fusion" class="mw-redirect" title="Heat of fusion">heats of fusion</a>, <a href="/wiki/Heat_of_vaporisation" class="mw-redirect" title="Heat of vaporisation">heats of vaporization</a>, <a href="/wiki/Atomisation_energy" class="mw-redirect" title="Atomisation energy">atomisation energy</a>, and so on. Similar periodic variations appear for the compounds of the elements, which can be observed by comparing hydrides, oxides, sulfides, halides, and so on.<sup id="cite_ref-Greenwood25_157-3" class="reference"><a href="#cite_note-Greenwood25-157"><span class="cite-bracket">[</span>144<span class="cite-bracket">]</span></a></sup> Chemical properties are more difficult to describe quantitatively, but likewise exhibit their own periodicities. Examples include the variation in the <a href="/wiki/Acid" title="Acid">acidic</a> and <a href="/wiki/Base_(chemistry)" title="Base (chemistry)">basic</a> properties of the elements and their compounds, the stabilities of compounds, and methods of isolating the elements.<sup id="cite_ref-Greenwood27_123-4" class="reference"><a href="#cite_note-Greenwood27-123"><span class="cite-bracket">[</span>113<span class="cite-bracket">]</span></a></sup> Periodicity is and has been used very widely to predict the properties of unknown new elements and new compounds, and is central to modern chemistry.<sup id="cite_ref-Greenwood29bis_199-0" class="reference"><a href="#cite_note-Greenwood29bis-199"><span class="cite-bracket">[</span>181<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Classification_of_elements">Classification of elements</h2></div> <figure class="mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Simple_Periodic_Table_Chart-en.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/2/2e/Simple_Periodic_Table_Chart-en.svg/512px-Simple_Periodic_Table_Chart-en.svg.png" decoding="async" width="512" height="271" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/2e/Simple_Periodic_Table_Chart-en.svg/768px-Simple_Periodic_Table_Chart-en.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/2e/Simple_Periodic_Table_Chart-en.svg/1024px-Simple_Periodic_Table_Chart-en.svg.png 2x" data-file-width="1205" data-file-height="638" /></a><figcaption>A periodic table colour-coded to show some commonly used sets of similar elements. The categories and their boundaries differ somewhat between sources.<sup id="cite_ref-ACS_192-1" class="reference"><a href="#cite_note-ACS-192"><span class="cite-bracket">[</span>175<span class="cite-bracket">]</span></a></sup> Lutetium and lawrencium in group 3 are also transition metals.<sup id="cite_ref-jensenlaw_66-21" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup><style data-mw-deduplicate="TemplateStyles:r1216972533">.mw-parser-output .col-begin{border-collapse:collapse;padding:0;color:inherit;width:100%;border:0;margin:0}.mw-parser-output .col-begin-small{font-size:90%}.mw-parser-output .col-break{vertical-align:top;text-align:left}.mw-parser-output .col-break-2{width:50%}.mw-parser-output .col-break-3{width:33.3%}.mw-parser-output .col-break-4{width:25%}.mw-parser-output .col-break-5{width:20%}@media(max-width:720px){.mw-parser-output .col-begin,.mw-parser-output .col-begin>tbody,.mw-parser-output .col-begin>tbody>tr,.mw-parser-output .col-begin>tbody>tr>td{display:block!important;width:100%!important}.mw-parser-output .col-break{padding-left:0!important}}</style><div> <table class="col-begin" role="presentation"> <tbody><tr> <td class="col-break"><style data-mw-deduplicate="TemplateStyles:r981673959">.mw-parser-output .legend{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .legend-color{display:inline-block;min-width:1.25em;height:1.25em;line-height:1.25;margin:1px 0;text-align:center;border:1px solid black;background-color:transparent;color:black}.mw-parser-output .legend-text{}</style><span class="legend nowrap"><span class="legend-color mw-no-invert" style="background-color:#ff9d9d; color:black;"> </span> </span> <a href="/wiki/Alkali_metals" class="mw-redirect" title="Alkali metals">Alkali metals</a><br /><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r981673959"><span class="legend nowrap"><span class="legend-color mw-no-invert" style="background-color:#ffdead; color:black;"> </span> </span> <a href="/wiki/Alkaline_earth_metals" class="mw-redirect" title="Alkaline earth metals">Alkaline earth metals</a><br /><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r981673959"><span class="legend nowrap"><span class="legend-color mw-no-invert" style="background-color:#ffbfff; color:black;"> </span> </span> <a href="/wiki/Lanthanides" class="mw-redirect" title="Lanthanides">Lanthanides</a><br /><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r981673959"><span class="legend nowrap"><span class="legend-color mw-no-invert" style="background-color:#ff99cc; color:black;"> </span> </span> <a href="/wiki/Actinides" class="mw-redirect" title="Actinides">Actinides</a><br /><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r981673959"><span class="legend nowrap"><span class="legend-color mw-no-invert" style="background-color:#ffc0c0; color:black;"> </span> </span> <a href="/wiki/Transition_metals" class="mw-redirect" title="Transition metals">Transition metals</a> </td> <td class="col-break"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r981673959"><span class="legend nowrap"><span class="legend-color mw-no-invert" style="background-color:#cccccc; color:black;"> </span> </span> <a href="/wiki/Other_metals" class="mw-redirect" title="Other metals">Other metals</a><br /><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r981673959"><span class="legend nowrap"><span class="legend-color mw-no-invert" style="background-color:#cccc99; color:black;"> </span> </span> <a href="/wiki/Metalloids" class="mw-redirect" title="Metalloids">Metalloids</a><br /><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r981673959"><span class="legend nowrap"><span class="legend-color mw-no-invert" style="background-color:#a0ffa0; color:black;"> </span> </span> <a href="/wiki/Other_nonmetal" class="mw-redirect" title="Other nonmetal">Other nonmetals</a><br /><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r981673959"><span class="legend nowrap"><span class="legend-color mw-no-invert" style="background-color:#ffff99; color:black;"> </span> </span> <a href="/wiki/Halogens" class="mw-redirect" title="Halogens">Halogens</a><br /><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r981673959"><span class="legend nowrap"><span class="legend-color mw-no-invert" style="background-color:#c0ffff; color:black;"> </span> </span> <a href="/wiki/Noble_gases" class="mw-redirect" title="Noble gases">Noble gases</a>  </td></tr></tbody></table></div></figcaption></figure> <p>Many terms have been used in the literature to describe sets of elements that behave similarly. The group names <i>alkali metal</i>, <i>alkaline earth metal</i>, <i>triel</i>, <i>tetrel</i>, <i>pnictogen</i>, <i>chalcogen</i>, <i>halogen</i>, and <i>noble gas</i> are acknowledged by IUPAC; the other groups can be referred to by their number, or by their first element (e.g., group 6 is the chromium group).<sup id="cite_ref-IUPAC_26-2" class="reference"><a href="#cite_note-IUPAC-26"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-200" class="reference"><a href="#cite_note-200"><span class="cite-bracket">[</span>182<span class="cite-bracket">]</span></a></sup> Some divide the p-block elements from groups 13 to 16 by metallicity,<sup id="cite_ref-EB_194-1" class="reference"><a href="#cite_note-EB-194"><span class="cite-bracket">[</span>177<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-ACS_192-2" class="reference"><a href="#cite_note-ACS-192"><span class="cite-bracket">[</span>175<span class="cite-bracket">]</span></a></sup> although there is neither an IUPAC definition nor a precise consensus on exactly which elements should be considered metals, nonmetals, or semi-metals (sometimes called metalloids).<sup id="cite_ref-EB_194-2" class="reference"><a href="#cite_note-EB-194"><span class="cite-bracket">[</span>177<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-ACS_192-3" class="reference"><a href="#cite_note-ACS-192"><span class="cite-bracket">[</span>175<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-IUPAC_26-3" class="reference"><a href="#cite_note-IUPAC-26"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> Neither is there a consensus on what the metals succeeding the transition metals ought to be called, with <i><a href="/wiki/Post-transition_metal" title="Post-transition metal">post-transition metal</a></i> and <i>poor metal</i> being among the possibilities having been used. Some advanced monographs exclude the elements of group 12 from the transition metals on the grounds of their sometimes quite different chemical properties, but this is not a universal practice<sup id="cite_ref-201" class="reference"><a href="#cite_note-201"><span class="cite-bracket">[</span>183<span class="cite-bracket">]</span></a></sup> and IUPAC does not presently mention it as allowable in its <i>Principles of Chemical Nomenclature</i>.<sup id="cite_ref-202" class="reference"><a href="#cite_note-202"><span class="cite-bracket">[</span>184<span class="cite-bracket">]</span></a></sup> </p><p>The <i>lanthanides</i> are considered to be the elements La–Lu, which are all very similar to each other: historically they included only Ce–Lu, but lanthanum became included by common usage.<sup id="cite_ref-IUPAC_26-4" class="reference"><a href="#cite_note-IUPAC-26"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> The <i><a href="/wiki/Rare_earth_element" class="mw-redirect" title="Rare earth element">rare earth elements</a></i> (or rare earth metals) add scandium and yttrium to the lanthanides.<sup id="cite_ref-IUPAC_26-5" class="reference"><a href="#cite_note-IUPAC-26"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> Analogously, the <i>actinides</i> are considered to be the elements Ac–Lr (historically Th–Lr),<sup id="cite_ref-IUPAC_26-6" class="reference"><a href="#cite_note-IUPAC-26"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> although variation of properties in this set is much greater than within the lanthanides.<sup id="cite_ref-Jorgensen_59-6" class="reference"><a href="#cite_note-Jorgensen-59"><span class="cite-bracket">[</span>52<span class="cite-bracket">]</span></a></sup> IUPAC recommends the names <i>lanthanoids</i> and <i>actinoids</i> to avoid ambiguity, as the -ide suffix typically denotes a negative ion; however <i>lanthanides</i> and <i>actinides</i> remain common.<sup id="cite_ref-IUPAC_26-7" class="reference"><a href="#cite_note-IUPAC-26"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> With the increasing recognition of lutetium and lawrencium as d-block elements, some authors began to define the lanthanides as La–Yb and the actinides as Ac–No, matching the f-block.<sup id="cite_ref-KW_64-9" class="reference"><a href="#cite_note-KW-64"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Jensen1982_29-6" class="reference"><a href="#cite_note-Jensen1982-29"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-203" class="reference"><a href="#cite_note-203"><span class="cite-bracket">[</span>185<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-204" class="reference"><a href="#cite_note-204"><span class="cite-bracket">[</span>186<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-205" class="reference"><a href="#cite_note-205"><span class="cite-bracket">[</span>187<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-sacotton_206-0" class="reference"><a href="#cite_note-sacotton-206"><span class="cite-bracket">[</span>188<span class="cite-bracket">]</span></a></sup> The <i>transactinides</i> or <i><a href="/wiki/Superheavy_element" title="Superheavy element">superheavy elements</a></i> are the short-lived elements beyond the actinides, starting at lawrencium or rutherfordium (depending on where the actinides are taken to end).<sup id="cite_ref-sacotton_206-1" class="reference"><a href="#cite_note-sacotton-206"><span class="cite-bracket">[</span>188<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Neve_207-0" class="reference"><a href="#cite_note-Neve-207"><span class="cite-bracket">[</span>189<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Mingos_208-0" class="reference"><a href="#cite_note-Mingos-208"><span class="cite-bracket">[</span>190<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-209" class="reference"><a href="#cite_note-209"><span class="cite-bracket">[</span>191<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-210" class="reference"><a href="#cite_note-210"><span class="cite-bracket">[</span>192<span class="cite-bracket">]</span></a></sup> </p><p>Many more categorizations exist and are used according to certain disciplines. In astrophysics, a metal is defined as any element with atomic number greater than 2, i.e. anything except hydrogen and helium.<sup id="cite_ref-211" class="reference"><a href="#cite_note-211"><span class="cite-bracket">[</span>193<span class="cite-bracket">]</span></a></sup> The term "semimetal" has a different definition in physics than it does in chemistry: bismuth is a semimetal by physical definitions, but chemists generally consider it a metal.<sup id="cite_ref-212" class="reference"><a href="#cite_note-212"><span class="cite-bracket">[</span>194<span class="cite-bracket">]</span></a></sup> A few terms are widely used, but without any very formal definition, such as "<a href="/wiki/Heavy_metals" class="mw-redirect" title="Heavy metals">heavy metal</a>", which has been given such a wide range of definitions that it has been criticized as "effectively meaningless".<sup id="cite_ref-213" class="reference"><a href="#cite_note-213"><span class="cite-bracket">[</span>195<span class="cite-bracket">]</span></a></sup> </p><p>The scope of terms varies significantly between authors. For example, according to IUPAC, the noble gases extend to include the whole group, including the very radioactive superheavy element oganesson.<sup id="cite_ref-214" class="reference"><a href="#cite_note-214"><span class="cite-bracket">[</span>196<span class="cite-bracket">]</span></a></sup> However, among those who specialize in the superheavy elements, this is not often done: in this case "noble gas" is typically taken to imply the unreactive behaviour of the lighter elements of the group. Since calculations generally predict that oganesson should not be particularly inert due to relativistic effects, and may not even be a gas at room temperature if it could be produced in bulk, its status as a noble gas is often questioned in this context.<sup id="cite_ref-215" class="reference"><a href="#cite_note-215"><span class="cite-bracket">[</span>197<span class="cite-bracket">]</span></a></sup> Furthermore, national variations are sometimes encountered: in Japan, alkaline earth metals often do not include beryllium and magnesium as their behaviour is different from the heavier group 2 metals.<sup id="cite_ref-216" class="reference"><a href="#cite_note-216"><span class="cite-bracket">[</span>198<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="History">History</h2></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/History_of_the_periodic_table" title="History of the periodic table">History of the periodic table</a></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Timeline_of_chemical_element_discoveries" class="mw-redirect" title="Timeline of chemical element discoveries">Timeline of chemical element discoveries</a></div> <div class="mw-heading mw-heading3"><h3 id="Early_history">Early history</h3></div> <p>In 1817, German physicist <a href="/wiki/Johann_Wolfgang_D%C3%B6bereiner" title="Johann Wolfgang Döbereiner">Johann Wolfgang Döbereiner</a> began to formulate one of the earliest attempts to classify the elements.<sup id="cite_ref-217" class="reference"><a href="#cite_note-217"><span class="cite-bracket">[</span>199<span class="cite-bracket">]</span></a></sup> In 1829, he found that he could form some of the elements into groups of three, with the members of each group having related properties. He termed these groups <a href="/wiki/D%C3%B6bereiner%27s_triads" title="Döbereiner's triads">triads</a>.<sup id="cite_ref-218" class="reference"><a href="#cite_note-218"><span class="cite-bracket">[</span>200<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-219" class="reference"><a href="#cite_note-219"><span class="cite-bracket">[</span>201<span class="cite-bracket">]</span></a></sup> Chlorine, bromine, and iodine formed a triad; as did calcium, strontium, and barium; lithium, sodium, and potassium; and sulfur, selenium, and tellurium. Today, all these triads form part of modern-day groups: the halogens, alkaline earth metals, alkali metals, and chalcogens.<sup id="cite_ref-220" class="reference"><a href="#cite_note-220"><span class="cite-bracket">[</span>202<span class="cite-bracket">]</span></a></sup> Various chemists continued his work and were able to identify more and more relationships between small groups of elements. However, they could not build one scheme that encompassed them all.<sup id="cite_ref-221" class="reference"><a href="#cite_note-221"><span class="cite-bracket">[</span>203<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Newlands_periodiska_system_1866.png" class="mw-file-description"><img alt="Newlands's table of the elements." src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e5/Newlands_periodiska_system_1866.png/330px-Newlands_periodiska_system_1866.png" decoding="async" width="330" height="95" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/e/e5/Newlands_periodiska_system_1866.png 1.5x" data-file-width="425" data-file-height="122" /></a><figcaption>Newlands's table of the elements in 1866.</figcaption></figure> <p><a href="/wiki/John_Newlands_(chemist)" title="John Newlands (chemist)">John Newlands</a> published a letter in the <i>Chemical News</i> in February 1863 on the periodicity among the chemical elements.<sup id="cite_ref-EB1911_222-0" class="reference"><a href="#cite_note-EB1911-222"><span class="cite-bracket">[</span>204<span class="cite-bracket">]</span></a></sup> In 1864 Newlands published an article in the <i>Chemical News</i> showing that if the elements are arranged in the order of their atomic weights, those having consecutive numbers frequently either belong to the same group or occupy similar positions in different groups, and he pointed out that each eighth element starting from a given one is in this arrangement a kind of repetition of the first, like the eighth note of an octave in music (The Law of Octaves).<sup id="cite_ref-EB1911_222-1" class="reference"><a href="#cite_note-EB1911-222"><span class="cite-bracket">[</span>204<span class="cite-bracket">]</span></a></sup> However, Newlands's formulation only worked well for the main-group elements, and encountered serious problems with the others.<sup id="cite_ref-jensenlaw_66-22" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> </p><p>German chemist <a href="/wiki/Lothar_Meyer" title="Lothar Meyer">Lothar Meyer</a> noted the sequences of similar chemical and physical properties repeated at periodic intervals. According to him, if the atomic weights were plotted as ordinates (i.e. vertically) and the atomic volumes as abscissas (i.e. horizontally)—the curve obtained a series of maximums and minimums—the most <a href="/wiki/Electropositive" class="mw-redirect" title="Electropositive">electropositive</a> elements would appear at the peaks of the curve in the order of their atomic weights. In 1864, a book of his was published; it contained an early version of the periodic table containing 28 elements, and classified elements into six families by their <a href="/wiki/Valence_(chemistry)" title="Valence (chemistry)">valence</a>—for the first time, elements had been grouped according to their valence. Works on organizing the elements by atomic weight had until then been stymied by inaccurate measurements of the atomic weights.<sup id="cite_ref-Meyer_table_223-0" class="reference"><a href="#cite_note-Meyer_table-223"><span class="cite-bracket">[</span>205<span class="cite-bracket">]</span></a></sup> In 1868, he revised his table, but this revision was published as a draft only after his death.<sup id="cite_ref-224" class="reference"><a href="#cite_note-224"><span class="cite-bracket">[</span>206<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Mendeleev">Mendeleev</h3></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1237032888/mw-parser-output/.tmulti"><div class="thumb tmulti tright"><div class="thumbinner multiimageinner" style="width:692px;max-width:692px"><div class="trow"><div class="tsingle" style="width:199px;max-width:199px"><div class="thumbimage" style="height:242px;overflow:hidden"><span typeof="mw:File"><a href="/wiki/File:1869-periodic-table.jpg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e5/1869-periodic-table.jpg/197px-1869-periodic-table.jpg" decoding="async" width="197" height="242" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e5/1869-periodic-table.jpg/296px-1869-periodic-table.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e5/1869-periodic-table.jpg/394px-1869-periodic-table.jpg 2x" data-file-width="1067" data-file-height="1312" /></a></span></div><div class="thumbcaption"><a href="/wiki/Dmitri_Mendeleev" title="Dmitri Mendeleev">Mendeleev's</a> 1869 periodic table</div></div><div class="tsingle" style="width:489px;max-width:489px"><div class="thumbimage" style="height:242px;overflow:hidden"><span typeof="mw:File"><a href="/wiki/File:Mendelejevs_periodiska_system_1871.png" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/5/55/Mendelejevs_periodiska_system_1871.png/487px-Mendelejevs_periodiska_system_1871.png" decoding="async" width="487" height="243" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/5/55/Mendelejevs_periodiska_system_1871.png 1.5x" data-file-width="684" data-file-height="341" /></a></span></div><div class="thumbcaption"><a href="/wiki/Dmitri_Mendeleev" title="Dmitri Mendeleev">Mendeleev's</a> 1871 periodic table</div></div></div></div></div> <p>The definitive breakthrough came from the Russian chemist <a href="/wiki/Dmitri_Mendeleev" title="Dmitri Mendeleev">Dmitri Mendeleev</a>. Although other chemists (including Meyer) had found some other versions of the periodic system at about the same time, Mendeleev was the most dedicated to developing and defending his system, and it was his system that most affected the scientific community.<sup id="cite_ref-225" class="reference"><a href="#cite_note-225"><span class="cite-bracket">[</span>207<span class="cite-bracket">]</span></a></sup> On 17 February 1869 (1 March 1869 in the Gregorian calendar), Mendeleev began arranging the elements and comparing them by their atomic weights. He began with a few elements, and over the course of the day his system grew until it encompassed most of the known elements. After he found a consistent arrangement, his printed table appeared in May 1869 in the journal of the Russian Chemical Society.<sup id="cite_ref-Scerri117_226-0" class="reference"><a href="#cite_note-Scerri117-226"><span class="cite-bracket">[</span>208<span class="cite-bracket">]</span></a></sup> When elements did not appear to fit in the system, he boldly predicted that either valencies or atomic weights had been measured incorrectly, or that there was a missing element yet to be discovered.<sup id="cite_ref-jensenlaw_66-23" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> In 1871, Mendeleev published a long article, including an updated form of his table, that made his predictions for unknown elements explicit. Mendeleev predicted the properties of three of these unknown elements in detail: as they would be missing heavier homologues of boron, aluminium, and silicon, he named them eka-boron, eka-aluminium, and eka-silicon ("eka" being Sanskrit for "one").<sup id="cite_ref-Scerri117_226-1" class="reference"><a href="#cite_note-Scerri117-226"><span class="cite-bracket">[</span>208<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-mendeleev1871_227-0" class="reference"><a href="#cite_note-mendeleev1871-227"><span class="cite-bracket">[</span>209<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: 45">: 45 </span></sup> In 1875, the French chemist <a href="/wiki/Paul-%C3%89mile_Lecoq_de_Boisbaudran" title="Paul-Émile Lecoq de Boisbaudran">Paul-Émile Lecoq de Boisbaudran</a>, working without knowledge of Mendeleev's prediction, discovered a new element in a sample of the mineral <a href="/wiki/Sphalerite" title="Sphalerite">sphalerite</a>, and named it gallium. He isolated the element and began determining its properties. Mendeleev, reading de Boisbaudran's publication, sent a letter claiming that gallium was his predicted eka-aluminium. Although Lecoq de Boisbaudran was initially sceptical, and suspected that Mendeleev was trying to take credit for his discovery, he later admitted that Mendeleev was correct.<sup id="cite_ref-228" class="reference"><a href="#cite_note-228"><span class="cite-bracket">[</span>210<span class="cite-bracket">]</span></a></sup> In 1879, the Swedish chemist <a href="/wiki/Lars_Fredrik_Nilson" title="Lars Fredrik Nilson">Lars Fredrik Nilson</a> discovered a new element, which he named scandium: it turned out to be eka-boron. Eka-silicon was found in 1886 by German chemist <a href="/wiki/Clemens_Winkler" title="Clemens Winkler">Clemens Winkler</a>, who named it germanium. The properties of gallium, scandium, and germanium matched what Mendeleev had predicted.<sup id="cite_ref-229" class="reference"><a href="#cite_note-229"><span class="cite-bracket">[</span>211<span class="cite-bracket">]</span></a></sup> In 1889, Mendeleev noted at the Faraday Lecture to the Royal Institution in London that he had not expected to live long enough "to mention their discovery to the Chemical Society of Great Britain as a confirmation of the exactitude and generality of the periodic law".<sup id="cite_ref-230" class="reference"><a href="#cite_note-230"><span class="cite-bracket">[</span>212<span class="cite-bracket">]</span></a></sup> Even the discovery of the noble gases at the close of the 19th century, which Mendeleev had not predicted, fitted neatly into his scheme as an eighth main group.<sup id="cite_ref-Scerri164_231-0" class="reference"><a href="#cite_note-Scerri164-231"><span class="cite-bracket">[</span>213<span class="cite-bracket">]</span></a></sup> </p><p>Mendeleev nevertheless had some trouble fitting the known lanthanides into his scheme, as they did not exhibit the periodic change in valencies that the other elements did. After much investigation, the Czech chemist <a href="/wiki/Bohuslav_Brauner" title="Bohuslav Brauner">Bohuslav Brauner</a> suggested in 1902 that the lanthanides could all be placed together in one group on the periodic table. He named this the "asteroid hypothesis" as an astronomical analogy: just as there is an <a href="/wiki/Asteroid_belt" title="Asteroid belt">asteroid belt</a> instead of a single planet between Mars and Jupiter, so the place below yttrium was thought to be occupied by all the lanthanides instead of just one element.<sup id="cite_ref-Thyssen_37-4" class="reference"><a href="#cite_note-Thyssen-37"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Atomic_number">Atomic number</h3></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Extended_periodic_table_van_den_Broek.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e7/Extended_periodic_table_van_den_Broek.jpg/440px-Extended_periodic_table_van_den_Broek.jpg" decoding="async" width="440" height="344" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e7/Extended_periodic_table_van_den_Broek.jpg/660px-Extended_periodic_table_van_den_Broek.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e7/Extended_periodic_table_van_den_Broek.jpg/880px-Extended_periodic_table_van_den_Broek.jpg 2x" data-file-width="982" data-file-height="768" /></a><figcaption>Periodic table of <a href="/wiki/Antonius_van_den_Broek" title="Antonius van den Broek">Antonius van den Broek</a></figcaption></figure> <p>After the internal structure of the atom was probed, amateur Dutch physicist <a href="/wiki/Antonius_van_den_Broek" title="Antonius van den Broek">Antonius van den Broek</a> proposed in 1913 that the nuclear charge determined the placement of elements in the periodic table.<sup id="cite_ref-moseley2010_232-0" class="reference"><a href="#cite_note-moseley2010-232"><span class="cite-bracket">[</span>214<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-233" class="reference"><a href="#cite_note-233"><span class="cite-bracket">[</span>215<span class="cite-bracket">]</span></a></sup> The New Zealand physicist <a href="/wiki/Ernest_Rutherford" title="Ernest Rutherford">Ernest Rutherford</a> coined the word "atomic number" for this nuclear charge.<sup id="cite_ref-234" class="reference"><a href="#cite_note-234"><span class="cite-bracket">[</span>216<span class="cite-bracket">]</span></a></sup> In van den Broek's published article he illustrated the first electronic periodic table showing the elements arranged according to the number of their electrons.<sup id="cite_ref-235" class="reference"><a href="#cite_note-235"><span class="cite-bracket">[</span>217<span class="cite-bracket">]</span></a></sup> Rutherford confirmed in his 1914 paper that Bohr had accepted the view of van den Broek.<sup id="cite_ref-236" class="reference"><a href="#cite_note-236"><span class="cite-bracket">[</span>218<span class="cite-bracket">]</span></a></sup> </p><p>The same year, English physicist <a href="/wiki/Henry_Moseley" title="Henry Moseley">Henry Moseley</a> using <a href="/wiki/X-ray_spectroscopy" title="X-ray spectroscopy">X-ray spectroscopy</a> confirmed van den Broek's proposal experimentally. Moseley determined the value of the nuclear charge of each element from <a href="/wiki/Aluminium" title="Aluminium">aluminium</a> to <a href="/wiki/Gold" title="Gold">gold</a> and showed that Mendeleev's ordering actually places the elements in sequential order by nuclear charge.<sup id="cite_ref-237" class="reference"><a href="#cite_note-237"><span class="cite-bracket">[</span>219<span class="cite-bracket">]</span></a></sup> Nuclear charge is identical to <a href="/wiki/Proton" title="Proton">proton</a> count and determines the value of the <a href="/wiki/Atomic_number" title="Atomic number">atomic number</a> (<i>Z</i>) of each element. Using atomic number gives a definitive, integer-based sequence for the elements. Moseley's research immediately resolved discrepancies between atomic weight and chemical properties; these were cases such as tellurium and iodine, where atomic number increases but atomic weight decreases.<sup id="cite_ref-moseley2010_232-1" class="reference"><a href="#cite_note-moseley2010-232"><span class="cite-bracket">[</span>214<span class="cite-bracket">]</span></a></sup> Although Moseley was soon killed in World War I, the Swedish physicist <a href="/wiki/Manne_Siegbahn" title="Manne Siegbahn">Manne Siegbahn</a> continued his work up to <a href="/wiki/Uranium" title="Uranium">uranium</a>, and established that it was the element with the highest atomic number then known (92).<sup id="cite_ref-238" class="reference"><a href="#cite_note-238"><span class="cite-bracket">[</span>220<span class="cite-bracket">]</span></a></sup> Based on Moseley and Siegbahn's research, it was also known which atomic numbers corresponded to missing elements yet to be found: 43, 61, 72, 75, 85, and 87.<sup id="cite_ref-moseley2010_232-2" class="reference"><a href="#cite_note-moseley2010-232"><span class="cite-bracket">[</span>214<span class="cite-bracket">]</span></a></sup> (Element 75 had in fact already been found by Japanese chemist <a href="/wiki/Masataka_Ogawa" title="Masataka Ogawa">Masataka Ogawa</a> in 1908 and named <i>nipponium</i>, but he mistakenly assigned it as element 43 instead of 75 and so his discovery was not generally recognized until later. The contemporarily accepted discovery of element 75 came in 1925, when <a href="/wiki/Walter_Noddack" title="Walter Noddack">Walter Noddack</a>, <a href="/wiki/Ida_Tacke" class="mw-redirect" title="Ida Tacke">Ida Tacke</a>, and <a href="/wiki/Otto_Berg_(scientist)" title="Otto Berg (scientist)">Otto Berg</a> independently rediscovered it and gave it its present name, <a href="/wiki/Rhenium" title="Rhenium">rhenium</a>.)<sup id="cite_ref-nipponium2022_239-0" class="reference"><a href="#cite_note-nipponium2022-239"><span class="cite-bracket">[</span>221<span class="cite-bracket">]</span></a></sup> </p><p>The dawn of atomic physics also clarified the situation of <a href="/wiki/Isotope" title="Isotope">isotopes</a>. In the <a href="/wiki/Decay_chain" title="Decay chain">decay chains</a> of the primordial radioactive elements thorium and uranium, it soon became evident that there were many apparent new elements that had different atomic weights but exactly the same chemical properties. In 1913, <a href="/wiki/Frederick_Soddy" title="Frederick Soddy">Frederick Soddy</a> coined the term "isotope" to describe this situation, and considered isotopes to merely be different forms of the same chemical element. This furthermore clarified discrepancies such as tellurium and iodine: tellurium's natural isotopic composition is weighted towards heavier isotopes than iodine's, but tellurium has a lower atomic number.<sup id="cite_ref-7elements_240-0" class="reference"><a href="#cite_note-7elements-240"><span class="cite-bracket">[</span>222<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Electron_shells">Electron shells</h3></div> <p>The Danish physicist <a href="/wiki/Niels_Bohr" title="Niels Bohr">Niels Bohr</a> applied <a href="/wiki/Max_Planck" title="Max Planck">Max Planck</a>'s idea of quantization to the atom. He concluded that the energy levels of electrons were quantised: only a discrete set of stable energy states were allowed. Bohr then attempted to understand periodicity through electron configurations, surmising in 1913 that the inner electrons should be responsible for the chemical properties of the element.<sup id="cite_ref-241" class="reference"><a href="#cite_note-241"><span class="cite-bracket">[</span>223<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-242" class="reference"><a href="#cite_note-242"><span class="cite-bracket">[</span>224<span class="cite-bracket">]</span></a></sup> In 1913, he produced the first electronic periodic table based on a quantum atom.<sup id="cite_ref-Scerri208_243-0" class="reference"><a href="#cite_note-Scerri208-243"><span class="cite-bracket">[</span>225<span class="cite-bracket">]</span></a></sup> </p><p>Bohr called his electron shells "rings" in 1913: atomic orbitals within shells did not exist at the time of his planetary model. Bohr explains in Part 3 of his famous 1913 paper that the maximum electrons in a shell is eight, writing, "We see, further, that a ring of <var style="padding-right: 1px;">n</var> electrons cannot rotate in a single ring round a nucleus of charge ne unless <var style="padding-right: 1px;">n</var> < 8." For smaller atoms, the electron shells would be filled as follows: "rings of electrons will only join if they contain equal numbers of electrons; and that accordingly the numbers of electrons on inner rings will only be 2, 4, 8." However, in larger atoms the innermost shell would contain eight electrons: "on the other hand, the periodic system of the elements strongly suggests that already in neon <var style="padding-right: 1px;">N</var> = 10 an inner ring of eight electrons will occur." His proposed electron configurations for the atoms (shown to the right) mostly do not accord with those now known.<sup id="cite_ref-244" class="reference"><a href="#cite_note-244"><span class="cite-bracket">[</span>226<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-245" class="reference"><a href="#cite_note-245"><span class="cite-bracket">[</span>227<span class="cite-bracket">]</span></a></sup> They were improved further after the work of <a href="/wiki/Arnold_Sommerfeld" title="Arnold Sommerfeld">Arnold Sommerfeld</a> and <a href="/wiki/Edmund_Stoner" class="mw-redirect" title="Edmund Stoner">Edmund Stoner</a> discovered more quantum numbers.<sup id="cite_ref-7elements_240-1" class="reference"><a href="#cite_note-7elements-240"><span class="cite-bracket">[</span>222<span class="cite-bracket">]</span></a></sup> </p> <table class="wikitable" style="float:right; font-size:95%; margin:0.5em;"> <caption>Bohr's electron configurations for light elements </caption> <tbody><tr> <th>Element</th> <th>Electrons per shell </th></tr> <tr> <td>4</td> <td>2,2 </td></tr> <tr> <td>6</td> <td>2,4 </td></tr> <tr> <td>7</td> <td>4,3 </td></tr> <tr> <td>8</td> <td>4,2,2 </td></tr> <tr> <td>9</td> <td>4,4,1 </td></tr> <tr> <td>10</td> <td>8,2 </td></tr> <tr> <td>11</td> <td>8,2,1 </td></tr> <tr> <td>16</td> <td>8,4,2,2 </td></tr> <tr> <td>18</td> <td>8,8,2 </td></tr></tbody></table> <p>The first one to systematically expand and correct the chemical potentials of Bohr's atomic theory was <a href="/wiki/Walther_Kossel" title="Walther Kossel">Walther Kossel</a> in 1914 and in 1916. Kossel explained that in the periodic table new elements would be created as electrons were added to the outer shell. In Kossel's paper, he writes: "This leads to the conclusion that the electrons, which are added further, should be put into concentric rings or shells, on each of which ... only a certain number of electrons—namely, eight in our case—should be arranged. As soon as one ring or shell is completed, a new one has to be started for the next element; the number of electrons, which are most easily accessible, and lie at the outermost periphery, increases again from element to element and, therefore, in the formation of each new shell the chemical periodicity is repeated."<sup id="cite_ref-246" class="reference"><a href="#cite_note-246"><span class="cite-bracket">[</span>228<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-247" class="reference"><a href="#cite_note-247"><span class="cite-bracket">[</span>229<span class="cite-bracket">]</span></a></sup> </p><p>In a 1919 paper, <a href="/wiki/Irving_Langmuir" title="Irving Langmuir">Irving Langmuir</a> postulated the existence of "cells" which we now call orbitals, which could each only contain two electrons each, and these were arranged in "equidistant layers" which we now call shells. He made an exception for the first shell to only contain two electrons.<sup id="cite_ref-248" class="reference"><a href="#cite_note-248"><span class="cite-bracket">[</span>230<span class="cite-bracket">]</span></a></sup> The chemist <a href="/wiki/Charles_Rugeley_Bury" title="Charles Rugeley Bury">Charles Rugeley Bury</a> suggested in 1921 that eight and eighteen electrons in a shell form stable configurations. Bury proposed that the electron configurations in transitional elements depended upon the valence electrons in their outer shell.<sup id="cite_ref-Bury_249-0" class="reference"><a href="#cite_note-Bury-249"><span class="cite-bracket">[</span>231<span class="cite-bracket">]</span></a></sup> He introduced the word <i>transition</i> to describe the elements now known as <a href="/wiki/Transition_metal" title="Transition metal">transition metals</a> or transition elements.<sup id="cite_ref-Jensen2003_250-0" class="reference"><a href="#cite_note-Jensen2003-250"><span class="cite-bracket">[</span>232<span class="cite-bracket">]</span></a></sup> Bohr's theory was vindicated by the discovery of element 72: <a href="/wiki/Georges_Urbain" title="Georges Urbain">Georges Urbain</a> claimed to have discovered it as the <a href="/wiki/Rare_earth_element" class="mw-redirect" title="Rare earth element">rare earth element</a> <i>celtium</i>, but Bury and Bohr had predicted that element 72 could not be a rare earth element and had to be a homologue of <a href="/wiki/Zirconium" title="Zirconium">zirconium</a>. <a href="/wiki/Dirk_Coster" title="Dirk Coster">Dirk Coster</a> and <a href="/wiki/Georg_von_Hevesy" class="mw-redirect" title="Georg von Hevesy">Georg von Hevesy</a> searched for the element in zirconium ores and found element 72, which they named <a href="/wiki/Hafnium" title="Hafnium">hafnium</a> after Bohr's hometown of <a href="/wiki/Copenhagen" title="Copenhagen">Copenhagen</a> (<i>Hafnia</i> in Latin).<sup id="cite_ref-CosterHevesy1923_251-0" class="reference"><a href="#cite_note-CosterHevesy1923-251"><span class="cite-bracket">[</span>233<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-252" class="reference"><a href="#cite_note-252"><span class="cite-bracket">[</span>234<span class="cite-bracket">]</span></a></sup> Urbain's celtium proved to be simply purified <a href="/wiki/Lutetium" title="Lutetium">lutetium</a> (element 71).<sup id="cite_ref-253" class="reference"><a href="#cite_note-253"><span class="cite-bracket">[</span>235<span class="cite-bracket">]</span></a></sup> Hafnium and rhenium thus became the last stable elements to be discovered.<sup id="cite_ref-7elements_240-2" class="reference"><a href="#cite_note-7elements-240"><span class="cite-bracket">[</span>222<span class="cite-bracket">]</span></a></sup> </p><p>Prompted by Bohr, <a href="/wiki/Wolfgang_Pauli" title="Wolfgang Pauli">Wolfgang Pauli</a> took up the problem of electron configurations in 1923. Pauli extended Bohr's scheme to use four <a href="/wiki/Quantum_number" title="Quantum number">quantum numbers</a>, and formulated his <a href="/wiki/Pauli_exclusion_principle" title="Pauli exclusion principle">exclusion principle</a> which stated that no two electrons could have the same four quantum numbers. This explained the lengths of the periods in the periodic table (2, 8, 18, and 32), which corresponded to the number of electrons that each shell could occupy.<sup id="cite_ref-Scerri218_254-0" class="reference"><a href="#cite_note-Scerri218-254"><span class="cite-bracket">[</span>236<span class="cite-bracket">]</span></a></sup> In 1925, <a href="/wiki/Friedrich_Hund" title="Friedrich Hund">Friedrich Hund</a> arrived at configurations close to the modern ones.<sup id="cite_ref-255" class="reference"><a href="#cite_note-255"><span class="cite-bracket">[</span>237<span class="cite-bracket">]</span></a></sup> As a result of these advances, periodicity became based on the number of chemically active or valence electrons rather than by the valences of the elements.<sup id="cite_ref-jensenlaw_66-24" class="reference"><a href="#cite_note-jensenlaw-66"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> The <a href="/wiki/Aufbau_principle" title="Aufbau principle">Aufbau principle</a> that describes the electron configurations of the elements was first empirically observed by <a href="/wiki/Erwin_Madelung" title="Erwin Madelung">Erwin Madelung</a> in 1926,<sup id="cite_ref-Goudsmit_51-3" class="reference"><a href="#cite_note-Goudsmit-51"><span class="cite-bracket">[</span>45<span class="cite-bracket">]</span></a></sup> though the first to publish it was <a href="/wiki/Vladimir_Karapetoff" title="Vladimir Karapetoff">Vladimir Karapetoff</a> in 1930.<sup id="cite_ref-256" class="reference"><a href="#cite_note-256"><span class="cite-bracket">[</span>238<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Ostro_257-0" class="reference"><a href="#cite_note-Ostro-257"><span class="cite-bracket">[</span>239<span class="cite-bracket">]</span></a></sup> In 1961, <a href="/wiki/Vsevolod_Klechkovsky" title="Vsevolod Klechkovsky">Vsevolod Klechkovsky</a> derived the first part of the Madelung rule (that orbitals fill in order of increasing <i>n</i> + ℓ) from the <a href="/wiki/Thomas%E2%80%93Fermi_model" title="Thomas–Fermi model">Thomas–Fermi model</a>;<sup id="cite_ref-258" class="reference"><a href="#cite_note-258"><span class="cite-bracket">[</span>240<span class="cite-bracket">]</span></a></sup> the complete rule was derived from a similar potential in 1971 by Yury N. Demkov and Valentin N. Ostrovsky.<sup id="cite_ref-DO_259-0" class="reference"><a href="#cite_note-DO-259"><span class="cite-bracket">[</span>241<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-260" class="reference"><a href="#cite_note-260"><span class="cite-bracket">[</span>s<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Taula_peri%C3%B2dica_de_Werner_(1905).gif" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a0/Taula_peri%C3%B2dica_de_Werner_%281905%29.gif/512px-Taula_peri%C3%B2dica_de_Werner_%281905%29.gif" decoding="async" width="512" height="194" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a0/Taula_peri%C3%B2dica_de_Werner_%281905%29.gif/768px-Taula_peri%C3%B2dica_de_Werner_%281905%29.gif 1.5x, //upload.wikimedia.org/wikipedia/commons/a/a0/Taula_peri%C3%B2dica_de_Werner_%281905%29.gif 2x" data-file-width="774" data-file-height="293" /></a><figcaption>Periodic table of Alfred Werner (1905), the first appearance of the long form<sup id="cite_ref-Thyssen_37-5" class="reference"><a href="#cite_note-Thyssen-37"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup></figcaption></figure> <p>The quantum theory clarified the transition metals and lanthanides as forming their own separate groups, transitional between the main groups, although some chemists had already proposed tables showing them this way before then: the English chemist Henry Bassett did so in 1892, the Danish chemist <a href="/wiki/Julius_Thomsen" class="mw-redirect" title="Julius Thomsen">Julius Thomsen</a> in 1895, and the Swiss chemist <a href="/wiki/Alfred_Werner" title="Alfred Werner">Alfred Werner</a> in 1905. Bohr used Thomsen's form in his 1922 Nobel Lecture; Werner's form is very similar to the modern 32-column form. In particular, this supplanted Brauner's asteroidal hypothesis.<sup id="cite_ref-Thyssen_37-6" class="reference"><a href="#cite_note-Thyssen-37"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> </p><p>The exact position of the lanthanides, and thus the composition of <a href="/wiki/Group_3_element" title="Group 3 element">group 3</a>, remained under dispute for decades longer because their electron configurations were initially measured incorrectly.<sup id="cite_ref-Jensen1982_29-7" class="reference"><a href="#cite_note-Jensen1982-29"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-PTSS_102-2" class="reference"><a href="#cite_note-PTSS-102"><span class="cite-bracket">[</span>92<span class="cite-bracket">]</span></a></sup> On chemical grounds Bassett, Werner, and Bury grouped scandium and yttrium with lutetium rather than lanthanum (the former two left an empty space below yttrium as lutetium had not yet been discovered).<sup id="cite_ref-Thyssen_37-7" class="reference"><a href="#cite_note-Thyssen-37"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Bury_249-1" class="reference"><a href="#cite_note-Bury-249"><span class="cite-bracket">[</span>231<span class="cite-bracket">]</span></a></sup> Hund assumed in 1927 that all the lanthanide atoms had configuration [Xe]4f<sup>0−14</sup>5d<sup>1</sup>6s<sup>2</sup>, on account of their prevailing trivalency. It is now known that the relationship between chemistry and electron configuration is more complicated than that.<sup id="cite_ref-261" class="reference"><a href="#cite_note-261"><span class="cite-bracket">[</span>t<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-rareearths_61-4" class="reference"><a href="#cite_note-rareearths-61"><span class="cite-bracket">[</span>54<span class="cite-bracket">]</span></a></sup> Early spectroscopic evidence seemed to confirm these configurations, and thus the periodic table was structured to have group 3 as scandium, yttrium, lanthanum, and actinium, with fourteen f-elements breaking up the d-block between lanthanum and hafnium.<sup id="cite_ref-Jensen1982_29-8" class="reference"><a href="#cite_note-Jensen1982-29"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> But it was later discovered that this is only true for four of the fifteen lanthanides (lanthanum, cerium, gadolinium, and lutetium), and that the other lanthanide atoms do not have a d-electron. In particular, ytterbium completes the 4f shell and thus Soviet physicists Lev Landau and Evgeny Lifshitz noted in 1948 that lutetium is correctly regarded as a d-block rather than an f-block element;<sup id="cite_ref-Landau_30-2" class="reference"><a href="#cite_note-Landau-30"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> that bulk lanthanum is an f-metal was first suggested by <a href="/wiki/Jun_Kond%C5%8D" title="Jun Kondō">Jun Kondō</a> in 1963, on the grounds of its low-temperature <a href="/wiki/Superconductivity" title="Superconductivity">superconductivity</a>.<sup id="cite_ref-Kondo_110-1" class="reference"><a href="#cite_note-Kondo-110"><span class="cite-bracket">[</span>100<span class="cite-bracket">]</span></a></sup> This clarified the importance of looking at low-lying excited states of atoms that can play a role in chemical environments when classifying elements by block and positioning them on the table.<sup id="cite_ref-Hamilton_72-2" class="reference"><a href="#cite_note-Hamilton-72"><span class="cite-bracket">[</span>63<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-JensenLr_74-2" class="reference"><a href="#cite_note-JensenLr-74"><span class="cite-bracket">[</span>65<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Jensen1982_29-9" class="reference"><a href="#cite_note-Jensen1982-29"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> Many authors subsequently rediscovered this correction based on physical, chemical, and electronic concerns and applied it to all the relevant elements, thus making group 3 contain scandium, yttrium, lutetium, and lawrencium<sup id="cite_ref-Hamilton_72-3" class="reference"><a href="#cite_note-Hamilton-72"><span class="cite-bracket">[</span>63<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Fluck_27-6" class="reference"><a href="#cite_note-Fluck-27"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-PTSS_102-3" class="reference"><a href="#cite_note-PTSS-102"><span class="cite-bracket">[</span>92<span class="cite-bracket">]</span></a></sup> and having lanthanum through ytterbium and actinium through nobelium as the f-block rows:<sup id="cite_ref-Hamilton_72-4" class="reference"><a href="#cite_note-Hamilton-72"><span class="cite-bracket">[</span>63<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Fluck_27-7" class="reference"><a href="#cite_note-Fluck-27"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> this corrected version achieves consistency with the Madelung rule and vindicates Bassett, Werner, and Bury's initial chemical placement.<sup id="cite_ref-Thyssen_37-8" class="reference"><a href="#cite_note-Thyssen-37"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> </p><p>In 1988, IUPAC released a report supporting this composition of group 3,<sup id="cite_ref-Fluck_27-8" class="reference"><a href="#cite_note-Fluck-27"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> a decision that was reaffirmed in 2021.<sup id="cite_ref-2021IUPAC_28-7" class="reference"><a href="#cite_note-2021IUPAC-28"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> Variation can still be found in textbooks on the composition of group 3,<sup id="cite_ref-2015IUPAC_39-1" class="reference"><a href="#cite_note-2015IUPAC-39"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup> and some argumentation against this format is still published today,<sup id="cite_ref-Jensen2015_31-3" class="reference"><a href="#cite_note-Jensen2015-31"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup> but chemists and physicists who have considered the matter largely agree on group 3 containing scandium, yttrium, lutetium, and lawrencium and challenge the counterarguments as being inconsistent.<sup id="cite_ref-Jensen2015_31-4" class="reference"><a href="#cite_note-Jensen2015-31"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Synthetic_elements">Synthetic elements</h3></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Glenn_Seaborg_-_1964.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/47/Glenn_Seaborg_-_1964.jpg/220px-Glenn_Seaborg_-_1964.jpg" decoding="async" width="220" height="273" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/47/Glenn_Seaborg_-_1964.jpg/330px-Glenn_Seaborg_-_1964.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/47/Glenn_Seaborg_-_1964.jpg/440px-Glenn_Seaborg_-_1964.jpg 2x" data-file-width="2378" data-file-height="2949" /></a><figcaption>Glenn T. Seaborg</figcaption></figure> <p>By 1936, the pool of missing elements from hydrogen to uranium had shrunk to four: elements 43, 61, 85, and 87 remained missing. Element 43 eventually became the first element to be synthesized artificially via nuclear reactions rather than discovered in nature. It was discovered in 1937 by Italian chemists <a href="/wiki/Emilio_Segr%C3%A8" title="Emilio Segrè">Emilio Segrè</a> and <a href="/wiki/Carlo_Perrier" title="Carlo Perrier">Carlo Perrier</a>, who named their discovery <a href="/wiki/Technetium" title="Technetium">technetium</a>, after the Greek word for "artificial".<sup id="cite_ref-262" class="reference"><a href="#cite_note-262"><span class="cite-bracket">[</span>242<span class="cite-bracket">]</span></a></sup> Elements 61 (<a href="/wiki/Promethium" title="Promethium">promethium</a>) and 85 (<a href="/wiki/Astatine" title="Astatine">astatine</a>) were likewise produced artificially in 1945 and 1940 respectively; element 87 (<a href="/wiki/Francium" title="Francium">francium</a>) became the last element to be discovered in nature, by French chemist <a href="/wiki/Marguerite_Perey" title="Marguerite Perey">Marguerite Perey</a> in 1939.<sup id="cite_ref-263" class="reference"><a href="#cite_note-263"><span class="cite-bracket">[</span>243<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-264" class="reference"><a href="#cite_note-264"><span class="cite-bracket">[</span>u<span class="cite-bracket">]</span></a></sup> The elements beyond uranium were likewise discovered artificially, starting with <a href="/wiki/Edwin_McMillan" title="Edwin McMillan">Edwin McMillan</a> and <a href="/wiki/Philip_Abelson" title="Philip Abelson">Philip Abelson</a>'s 1940 discovery of <a href="/wiki/Neptunium" title="Neptunium">neptunium</a> (via bombardment of uranium with neutrons).<sup id="cite_ref-Scerri354_85-1" class="reference"><a href="#cite_note-Scerri354-85"><span class="cite-bracket">[</span>75<span class="cite-bracket">]</span></a></sup> <a href="/wiki/Glenn_T._Seaborg" title="Glenn T. Seaborg">Glenn T. Seaborg</a> and his team at the <a href="/wiki/Lawrence_Berkeley_National_Laboratory" title="Lawrence Berkeley National Laboratory">Lawrence Berkeley National Laboratory</a> (LBNL) continued discovering transuranium elements, starting with <a href="/wiki/Plutonium" title="Plutonium">plutonium</a> in 1941, and discovered that contrary to previous thinking, the elements from actinium onwards were congeners of the lanthanides rather than transition metals.<sup id="cite_ref-Seaborg_265-0" class="reference"><a href="#cite_note-Seaborg-265"><span class="cite-bracket">[</span>244<span class="cite-bracket">]</span></a></sup> Bassett (1892), Werner (1905), and the French engineer <a href="/wiki/Charles_Janet" title="Charles Janet">Charles Janet</a> (1928) had previously suggested this, but their ideas did not then receive general acceptance.<sup id="cite_ref-Thyssen_37-9" class="reference"><a href="#cite_note-Thyssen-37"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> Seaborg thus called them the actinides.<sup id="cite_ref-Seaborg_265-1" class="reference"><a href="#cite_note-Seaborg-265"><span class="cite-bracket">[</span>244<span class="cite-bracket">]</span></a></sup> Elements up to 101 (named mendelevium in honour of Mendeleev) were synthesized up to 1955, either through neutron or alpha-particle irradiation, or in nuclear explosions in the cases of 99 (einsteinium) and 100 (fermium).<sup id="cite_ref-Scerri354_85-2" class="reference"><a href="#cite_note-Scerri354-85"><span class="cite-bracket">[</span>75<span class="cite-bracket">]</span></a></sup> </p><p>A significant controversy arose with elements 102 through 106 in the 1960s and 1970s, as competition arose between the LBNL team (now led by <a href="/wiki/Albert_Ghiorso" title="Albert Ghiorso">Albert Ghiorso</a>) and a team of Soviet scientists at the <a href="/wiki/Joint_Institute_for_Nuclear_Research" title="Joint Institute for Nuclear Research">Joint Institute for Nuclear Research</a> (JINR) led by <a href="/wiki/Georgy_Flyorov" title="Georgy Flyorov">Georgy Flyorov</a>. Each team claimed discovery, and in some cases each proposed their own name for the element, creating an <a href="/wiki/Element_naming_controversy" class="mw-redirect" title="Element naming controversy">element naming controversy</a> that lasted decades. These elements were made by bombardment of actinides with light ions.<sup id="cite_ref-266" class="reference"><a href="#cite_note-266"><span class="cite-bracket">[</span>245<span class="cite-bracket">]</span></a></sup> IUPAC at first adopted a hands-off approach, preferring to wait and see if a consensus would be forthcoming. But as it was also the height of the <a href="/wiki/Cold_War" title="Cold War">Cold War</a>, it became clear that this would not happen. As such, IUPAC and the <a href="/wiki/International_Union_of_Pure_and_Applied_Physics" title="International Union of Pure and Applied Physics">International Union of Pure and Applied Physics</a> (IUPAP) created a <a href="/w/index.php?title=Transfermium_Working_Group&action=edit&redlink=1" class="new" title="Transfermium Working Group (page does not exist)">Transfermium Working Group</a> (TWG, fermium being element 100) in 1985 to set out criteria for discovery,<sup id="cite_ref-267" class="reference"><a href="#cite_note-267"><span class="cite-bracket">[</span>246<span class="cite-bracket">]</span></a></sup> which were published in 1991.<sup id="cite_ref-268" class="reference"><a href="#cite_note-268"><span class="cite-bracket">[</span>247<span class="cite-bracket">]</span></a></sup> After some further controversy, these elements received their final names in 1997, including seaborgium (106) in honour of Seaborg.<sup id="cite_ref-269" class="reference"><a href="#cite_note-269"><span class="cite-bracket">[</span>248<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Yuri_Oganessian.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/f/f2/Yuri_Oganessian.jpg/220px-Yuri_Oganessian.jpg" decoding="async" width="220" height="160" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/f2/Yuri_Oganessian.jpg/330px-Yuri_Oganessian.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/f2/Yuri_Oganessian.jpg/440px-Yuri_Oganessian.jpg 2x" data-file-width="992" data-file-height="722" /></a><figcaption>Yuri Oganessian</figcaption></figure> <p>The TWG's criteria were used to arbitrate later element discovery claims from LBNL and JINR, as well as from research institutes in Germany (<a href="/wiki/GSI_Helmholtz_Centre_for_Heavy_Ion_Research" title="GSI Helmholtz Centre for Heavy Ion Research">GSI</a>) and Japan (<a href="/wiki/Riken" title="Riken">Riken</a>).<sup id="cite_ref-270" class="reference"><a href="#cite_note-270"><span class="cite-bracket">[</span>249<span class="cite-bracket">]</span></a></sup> Currently, consideration of discovery claims is performed by a <a href="/wiki/IUPAC/IUPAP_Joint_Working_Party" title="IUPAC/IUPAP Joint Working Party">IUPAC/IUPAP Joint Working Party</a>. After priority was assigned, the elements were officially added to the periodic table, and the discoverers were invited to propose their names.<sup id="cite_ref-IUPAC-redbook_7-9" class="reference"><a href="#cite_note-IUPAC-redbook-7"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> By 2016, this had occurred for all elements up to 118, therefore completing the periodic table's first seven rows.<sup id="cite_ref-IUPAC-redbook_7-10" class="reference"><a href="#cite_note-IUPAC-redbook-7"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-finally_271-0" class="reference"><a href="#cite_note-finally-271"><span class="cite-bracket">[</span>250<span class="cite-bracket">]</span></a></sup> The discoveries of elements beyond 106 were made possible by techniques devised by <a href="/wiki/Yuri_Oganessian" title="Yuri Oganessian">Yuri Oganessian</a> at the JINR: cold fusion (bombardment of lead and bismuth by heavy ions) made possible the 1981–2004 discoveries of elements 107 through 112 at GSI and 113 at Riken, and he led the JINR team (in collaboration with American scientists) to discover elements 114 through 118 using hot fusion (bombardment of actinides by calcium ions) in 1998–2010.<sup id="cite_ref-272" class="reference"><a href="#cite_note-272"><span class="cite-bracket">[</span>251<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Chapman_273-0" class="reference"><a href="#cite_note-Chapman-273"><span class="cite-bracket">[</span>252<span class="cite-bracket">]</span></a></sup> The heaviest known element, oganesson (118), is named in Oganessian's honour. Element 114 is named flerovium in honour of his predecessor and mentor Flyorov.<sup id="cite_ref-Chapman_273-1" class="reference"><a href="#cite_note-Chapman-273"><span class="cite-bracket">[</span>252<span class="cite-bracket">]</span></a></sup> </p><p>In celebration of the periodic table's 150th anniversary, the <a href="/wiki/United_Nations" title="United Nations">United Nations</a> declared the year 2019 as the International Year of the Periodic Table, celebrating "one of the most significant achievements in science".<sup id="cite_ref-:1_274-0" class="reference"><a href="#cite_note-:1-274"><span class="cite-bracket">[</span>253<span class="cite-bracket">]</span></a></sup> The discovery criteria set down by the TWG were updated in 2020 in response to experimental and theoretical progress that had not been foreseen in 1991.<sup id="cite_ref-275" class="reference"><a href="#cite_note-275"><span class="cite-bracket">[</span>254<span class="cite-bracket">]</span></a></sup> Today, the periodic table is among the most recognisable icons of chemistry.<sup id="cite_ref-Lemonick_91-2" class="reference"><a href="#cite_note-Lemonick-91"><span class="cite-bracket">[</span>81<span class="cite-bracket">]</span></a></sup> IUPAC is involved today with many processes relating to the periodic table: the recognition and naming of new elements, recommending group numbers and collective names, and the updating of atomic weights.<sup id="cite_ref-IUPAC-redbook_7-11" class="reference"><a href="#cite_note-IUPAC-redbook-7"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Future_extension_beyond_the_seventh_period">Future extension beyond the seventh period</h2></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Extended_periodic_table" title="Extended periodic table">Extended periodic table</a></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Island_of_stability" title="Island of stability">Island of stability</a></div> <figure class="mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Energy_eigenvalues_superheavy.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Energy_eigenvalues_superheavy.svg/512px-Energy_eigenvalues_superheavy.svg.png" decoding="async" width="512" height="353" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Energy_eigenvalues_superheavy.svg/768px-Energy_eigenvalues_superheavy.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Energy_eigenvalues_superheavy.svg/1024px-Energy_eigenvalues_superheavy.svg.png 2x" data-file-width="608" data-file-height="419" /></a><figcaption>Energy eigenvalues (in eV) for the outermost electrons of elements with Z = 100 through 172, predicted using Dirac–Fock calculations. The − and + signs refer to orbitals with decreased or increased azimuthal quantum number from spin–orbit splitting respectively: p− is p<sub>1/2</sub>, p+ is p<sub>3/2</sub>, d− is d<sub>3/2</sub>, d+ is d<sub>5/2</sub>, f− is f<sub>5/2</sub>, f+ is f<sub>7/2</sub>, g− is g<sub>7/2</sub>, and g+ is g<sub>9/2</sub>.<sup id="cite_ref-BFricke_276-0" class="reference"><a href="#cite_note-BFricke-276"><span class="cite-bracket">[</span>255<span class="cite-bracket">]</span></a></sup> The spacing of energy levels up to <i>Z</i> = 120 is normal, and becomes normal again at <i>Z</i> = 157; between them, a very different situation is observed.<sup id="cite_ref-BFricke1977_277-0" class="reference"><a href="#cite_note-BFricke1977-277"><span class="cite-bracket">[</span>256<span class="cite-bracket">]</span></a></sup></figcaption></figure> <p>The most recently named elements – nihonium (113), moscovium (115), tennessine (117), and oganesson (118) – completed the seventh row of the periodic table.<sup id="cite_ref-IUPAC-redbook_7-12" class="reference"><a href="#cite_note-IUPAC-redbook-7"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> Future elements would have to begin an <a href="/wiki/Period_8_element" class="mw-redirect" title="Period 8 element">eighth row</a>. These elements may be referred to either by their atomic numbers (e.g. "<a href="/wiki/Extended_periodic_table" title="Extended periodic table">element 164</a>"), or by the IUPAC <a href="/wiki/Systematic_element_name" title="Systematic element name">systematic element names</a> adopted in 1978, which directly relate to the atomic numbers (e.g. "unhexquadium" for element 164, derived from Latin <i>unus</i> "one", Greek <i>hexa </i> "six", Latin <i>quadra</i> "four", and the traditional <i>-ium</i> suffix for metallic elements).<sup id="cite_ref-IUPAC-redbook_7-13" class="reference"><a href="#cite_note-IUPAC-redbook-7"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> All attempts to synthesize such elements have failed so far. An attempt to make element 119 has been ongoing since 2018 at the Riken research institute in Japan. The LBNL in the United States, the JINR in Russia, and the Heavy Ion Research Facility in <a href="/wiki/Lanzhou" title="Lanzhou">Lanzhou</a> (HIRFL) in China also plan to make their own attempts at synthesizing the first few period 8 elements.<sup id="cite_ref-nature2019_278-0" class="reference"><a href="#cite_note-nature2019-278"><span class="cite-bracket">[</span>257<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-SHEfactory_279-0" class="reference"><a href="#cite_note-SHEfactory-279"><span class="cite-bracket">[</span>258<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-280" class="reference"><a href="#cite_note-280"><span class="cite-bracket">[</span>259<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-281" class="reference"><a href="#cite_note-281"><span class="cite-bracket">[</span>260<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-282" class="reference"><a href="#cite_note-282"><span class="cite-bracket">[</span>261<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-283" class="reference"><a href="#cite_note-283"><span class="cite-bracket">[</span>262<span class="cite-bracket">]</span></a></sup> </p><p>If the eighth period followed the pattern set by the earlier periods, then it would contain fifty elements, filling the 8s, 5g, 6f, 7d, and finally 8p subshells in that order. But by this point, relativistic effects should result in significant deviations from the Madelung rule. Various different models have been suggested for the configurations of eighth-period elements, as well as how to show the results in a periodic table. All agree that the eighth period should begin like the previous ones with two 8s elements, 119 and <a href="/wiki/Unbinilium" title="Unbinilium">120</a>. However, after that the massive energetic overlaps between the 5g, 6f, 7d, and 8p subshells means that they all begin to fill together, and it is not clear how to separate out specific 5g and 6f series.<sup id="cite_ref-nefedov_67-1" class="reference"><a href="#cite_note-nefedov-67"><span class="cite-bracket">[</span>59<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-recentattempts_284-0" class="reference"><a href="#cite_note-recentattempts-284"><span class="cite-bracket">[</span>263<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-285" class="reference"><a href="#cite_note-285"><span class="cite-bracket">[</span>264<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Fricke_286-0" class="reference"><a href="#cite_note-Fricke-286"><span class="cite-bracket">[</span>265<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-PT172_287-0" class="reference"><a href="#cite_note-PT172-287"><span class="cite-bracket">[</span>266<span class="cite-bracket">]</span></a></sup> Elements <a href="/wiki/Unbiunium" title="Unbiunium">121</a> through 156 thus do not fit well as chemical analogues of any previous group in the earlier parts of the table,<sup id="cite_ref-actrev_139-1" class="reference"><a href="#cite_note-actrev-139"><span class="cite-bracket">[</span>128<span class="cite-bracket">]</span></a></sup> although they have sometimes been placed as 5g, 6f, and other series to formally reflect their electron configurations.<sup id="cite_ref-actrev_139-2" class="reference"><a href="#cite_note-actrev-139"><span class="cite-bracket">[</span>128<span class="cite-bracket">]</span></a></sup> Eric Scerri has raised the question of whether an extended periodic table should take into account the failure of the Madelung rule in this region, or if such exceptions should be ignored.<sup id="cite_ref-recentattempts_284-1" class="reference"><a href="#cite_note-recentattempts-284"><span class="cite-bracket">[</span>263<span class="cite-bracket">]</span></a></sup> The shell structure may also be fairly formal at this point: already the electron distribution in an oganesson atom is expected to be rather uniform, with no discernible shell structure.<sup id="cite_ref-oganesson-elf_288-0" class="reference"><a href="#cite_note-oganesson-elf-288"><span class="cite-bracket">[</span>267<span class="cite-bracket">]</span></a></sup> </p><p>The situation from elements 157 to 172 should return to normalcy and be more reminiscent of the earlier rows.<sup id="cite_ref-BFricke1977_277-1" class="reference"><a href="#cite_note-BFricke1977-277"><span class="cite-bracket">[</span>256<span class="cite-bracket">]</span></a></sup> The heavy p-shells are split by the <a href="/wiki/Spin%E2%80%93orbit_interaction" title="Spin–orbit interaction">spin–orbit interaction</a>: one p-orbital (p<sub>1/2</sub>) is more stabilized, and the other two (p<sub>3/2</sub>) are destabilized. (Such shifts in the quantum numbers happen for all types of shells, but it makes the biggest difference to the order for the p-shells.) It is likely that by element 157, the filled 8s and 8p<sub>1/2</sub> shells with four electrons in total have sunk into the core. Beyond the core, the next orbitals are 7d and 9s at similar energies, followed by 9p<sub>1/2</sub> and 8p<sub>3/2</sub> at similar energies, and then a large gap.<sup id="cite_ref-BFricke1977_277-2" class="reference"><a href="#cite_note-BFricke1977-277"><span class="cite-bracket">[</span>256<span class="cite-bracket">]</span></a></sup> Thus, the 9s and 9p<sub>1/2</sub> orbitals in essence replace the 8s and 8p<sub>1/2</sub> ones, making elements 157–172 probably chemically analogous to groups 3–18: for example, element 164 would appear two places below lead in group 14 under the usual pattern, but is calculated to be very analogous to palladium in group 10 instead.<sup id="cite_ref-rareearths_61-5" class="reference"><a href="#cite_note-rareearths-61"><span class="cite-bracket">[</span>54<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Fricke_286-1" class="reference"><a href="#cite_note-Fricke-286"><span class="cite-bracket">[</span>265<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-nefedov_67-2" class="reference"><a href="#cite_note-nefedov-67"><span class="cite-bracket">[</span>59<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-BFricke_276-1" class="reference"><a href="#cite_note-BFricke-276"><span class="cite-bracket">[</span>255<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-actrev_139-3" class="reference"><a href="#cite_note-actrev-139"><span class="cite-bracket">[</span>128<span class="cite-bracket">]</span></a></sup> Thus, it takes fifty-four elements rather than fifty to reach the next noble element after 118.<sup id="cite_ref-wothers_289-0" class="reference"><a href="#cite_note-wothers-289"><span class="cite-bracket">[</span>268<span class="cite-bracket">]</span></a></sup> However, while these conclusions about elements 157 through 172's chemistry are generally agreed by models,<sup id="cite_ref-actrev_139-4" class="reference"><a href="#cite_note-actrev-139"><span class="cite-bracket">[</span>128<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-nefedov_67-3" class="reference"><a href="#cite_note-nefedov-67"><span class="cite-bracket">[</span>59<span class="cite-bracket">]</span></a></sup> there is disagreement on whether the periodic table should be drawn to reflect chemical analogies, or if it should reflect likely formal electron configurations, which should be quite different from earlier periods and are not agreed between sources. Discussion about the format of the eighth row thus continues.<sup id="cite_ref-nefedov_67-4" class="reference"><a href="#cite_note-nefedov-67"><span class="cite-bracket">[</span>59<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Fricke_286-2" class="reference"><a href="#cite_note-Fricke-286"><span class="cite-bracket">[</span>265<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-PT172_287-1" class="reference"><a href="#cite_note-PT172-287"><span class="cite-bracket">[</span>266<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-smits_114-1" class="reference"><a href="#cite_note-smits-114"><span class="cite-bracket">[</span>104<span class="cite-bracket">]</span></a></sup> </p><p>Beyond element 172, calculation is complicated by the 1s electron energy level becoming imaginary. Such a situation does have physical interpretation, and does not in itself pose an electronic limit to the periodic table, but the correct way to incorporate such states into multi-electron calculations is still an open problem. This would need to be solved to continue calculating the periodic table's structure beyond this point.<sup id="cite_ref-gamowstates_290-0" class="reference"><a href="#cite_note-gamowstates-290"><span class="cite-bracket">[</span>269<span class="cite-bracket">]</span></a></sup> </p><p>Nuclear stability will likely prove a decisive factor constraining the number of possible elements. It depends on the balance between the electric repulsion between protons and the strong force binding protons and neutrons together.<sup id="cite_ref-291" class="reference"><a href="#cite_note-291"><span class="cite-bracket">[</span>270<span class="cite-bracket">]</span></a></sup> Protons and neutrons are arranged in <a href="/wiki/Nuclear_shell_model" title="Nuclear shell model">shells</a>, just like electrons, and so a closed shell can significantly increase stability: the known superheavy nuclei exist because of such a shell closure, probably at around 114–<a href="/wiki/Unbihexium" title="Unbihexium">126</a> protons and 184 neutrons.<sup id="cite_ref-gamowstates_290-1" class="reference"><a href="#cite_note-gamowstates-290"><span class="cite-bracket">[</span>269<span class="cite-bracket">]</span></a></sup> They are probably close to a predicted <a href="/wiki/Island_of_stability" title="Island of stability">island of stability</a>, where superheavy nuclides should be more long-lived than expected: predictions for the longest-lived nuclides on the island range from microseconds to millions of years.<sup id="cite_ref-smits_114-2" class="reference"><a href="#cite_note-smits-114"><span class="cite-bracket">[</span>104<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-physorg_292-0" class="reference"><a href="#cite_note-physorg-292"><span class="cite-bracket">[</span>271<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-nuclei_293-0" class="reference"><a href="#cite_note-nuclei-293"><span class="cite-bracket">[</span>272<span class="cite-bracket">]</span></a></sup> It should nonetheless be noted that these are essentially extrapolations into an unknown part of the chart of nuclides, and systematic model uncertainties need to be taken into account.<sup id="cite_ref-smits_114-3" class="reference"><a href="#cite_note-smits-114"><span class="cite-bracket">[</span>104<span class="cite-bracket">]</span></a></sup> </p><p>As the closed shells are passed, the stabilizing effect should vanish:<sup id="cite_ref-relqed_294-0" class="reference"><a href="#cite_note-relqed-294"><span class="cite-bracket">[</span>273<span class="cite-bracket">]</span></a></sup> thus, superheavy nuclides with more than 184 neutrons are expected to have much shorter lifetimes, spontaneously fissioning within 10<sup>−15</sup> seconds. If this is so, then it would not make sense to consider them chemical elements: IUPAC defines an element to exist only if the nucleus lives longer than 10<sup>−14</sup> seconds, the time needed for it to gather an electron cloud. Nonetheless, theoretical estimates of half-lives are very model-dependent, ranging over many orders of magnitude.<sup id="cite_ref-gamowstates_290-2" class="reference"><a href="#cite_note-gamowstates-290"><span class="cite-bracket">[</span>269<span class="cite-bracket">]</span></a></sup> The extreme repulsion between protons is predicted to result in exotic nuclear topologies, with bubbles, rings, and tori expected: this further complicates extrapolation.<sup id="cite_ref-smits_114-4" class="reference"><a href="#cite_note-smits-114"><span class="cite-bracket">[</span>104<span class="cite-bracket">]</span></a></sup> It is not clear if any further-out shell closures exist, due to an expected smearing out of distinct nuclear shells (as is already expected for the electron shells at oganesson).<sup id="cite_ref-relqed_294-1" class="reference"><a href="#cite_note-relqed-294"><span class="cite-bracket">[</span>273<span class="cite-bracket">]</span></a></sup> Furthermore, even if later shell closures exist, it is not clear if they would allow such heavy elements to exist.<sup id="cite_ref-greinernuclei_295-0" class="reference"><a href="#cite_note-greinernuclei-295"><span class="cite-bracket">[</span>274<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-radiochimica_296-0" class="reference"><a href="#cite_note-radiochimica-296"><span class="cite-bracket">[</span>275<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-PTSS1_297-0" class="reference"><a href="#cite_note-PTSS1-297"><span class="cite-bracket">[</span>276<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-EB_194-3" class="reference"><a href="#cite_note-EB-194"><span class="cite-bracket">[</span>177<span class="cite-bracket">]</span></a></sup> As such, it may be that the periodic table practically ends around element 120, as elements become too short-lived to observe, and then too short-lived to have chemistry; the era of discovering new elements would thus be close to its end.<sup id="cite_ref-EB_194-4" class="reference"><a href="#cite_note-EB-194"><span class="cite-bracket">[</span>177<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-298" class="reference"><a href="#cite_note-298"><span class="cite-bracket">[</span>277<span class="cite-bracket">]</span></a></sup> If another proton shell closure beyond 126 does exist, then it probably occurs around 164;<sup id="cite_ref-greinernuclei_295-1" class="reference"><a href="#cite_note-greinernuclei-295"><span class="cite-bracket">[</span>274<span class="cite-bracket">]</span></a></sup> thus the region where periodicity fails more or less matches the region of instability between the shell closures.<sup id="cite_ref-actrev_139-5" class="reference"><a href="#cite_note-actrev-139"><span class="cite-bracket">[</span>128<span class="cite-bracket">]</span></a></sup> </p><p>Alternatively, <a href="/wiki/Quark_matter" class="mw-redirect" title="Quark matter">quark matter</a> may become stable at high mass numbers, in which the nucleus is composed of freely flowing <a href="/wiki/Up_quark" title="Up quark">up</a> and <a href="/wiki/Down_quark" title="Down quark">down quarks</a> instead of binding them into protons and neutrons; this would create a <a href="/wiki/Continent_of_stability" title="Continent of stability">continent of stability</a> instead of an island.<sup id="cite_ref-udQM_299-0" class="reference"><a href="#cite_note-udQM-299"><span class="cite-bracket">[</span>278<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-udQMnew_300-0" class="reference"><a href="#cite_note-udQMnew-300"><span class="cite-bracket">[</span>279<span class="cite-bracket">]</span></a></sup> Other effects may come into play: for example, in very heavy elements the 1s electrons are likely to spend a significant amount of time so close to the nucleus that they are actually inside it, which would make them vulnerable to <a href="/wiki/Electron_capture" title="Electron capture">electron capture</a>.<sup id="cite_ref-colloq_301-0" class="reference"><a href="#cite_note-colloq-301"><span class="cite-bracket">[</span>280<span class="cite-bracket">]</span></a></sup> </p><p>Even if eighth-row elements can exist, producing them is likely to be difficult, and it should become even more difficult as atomic number rises.<sup id="cite_ref-302" class="reference"><a href="#cite_note-302"><span class="cite-bracket">[</span>281<span class="cite-bracket">]</span></a></sup> Although the 8s elements 119 and 120 are expected to be reachable with present means, the elements beyond that are expected to require new technology,<sup id="cite_ref-Zagrebaev_303-0" class="reference"><a href="#cite_note-Zagrebaev-303"><span class="cite-bracket">[</span>282<span class="cite-bracket">]</span></a></sup> if they can be produced at all.<sup id="cite_ref-Bloomberg_304-0" class="reference"><a href="#cite_note-Bloomberg-304"><span class="cite-bracket">[</span>283<span class="cite-bracket">]</span></a></sup> Experimentally characterizing these elements chemically would also pose a great challenge.<sup id="cite_ref-nature2019_278-1" class="reference"><a href="#cite_note-nature2019-278"><span class="cite-bracket">[</span>257<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Alternative_periodic_tables">Alternative periodic tables</h2></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Types_of_periodic_tables" title="Types of periodic tables">Types of periodic tables</a></div> <figure typeof="mw:File/Thumb"><a href="/wiki/File:Elementspiral_(polyatomic).svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/ce/Elementspiral_%28polyatomic%29.svg/350px-Elementspiral_%28polyatomic%29.svg.png" decoding="async" width="350" height="298" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/ce/Elementspiral_%28polyatomic%29.svg/525px-Elementspiral_%28polyatomic%29.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/ce/Elementspiral_%28polyatomic%29.svg/700px-Elementspiral_%28polyatomic%29.svg.png 2x" data-file-width="928" data-file-height="790" /></a><figcaption><a href="/wiki/Otto_Theodor_Benfey" title="Otto Theodor Benfey">Otto Theodor Benfey</a>'s spiral periodic table (1964)</figcaption></figure> <p>The periodic law may be represented in multiple ways, of which the standard periodic table is only one.<sup id="cite_ref-305" class="reference"><a href="#cite_note-305"><span class="cite-bracket">[</span>284<span class="cite-bracket">]</span></a></sup> Within 100 years of the appearance of Mendeleev's table in 1869, <a href="/wiki/Edward_G._Mazurs" title="Edward G. Mazurs">Edward G. Mazurs</a> had collected an estimated 700 different published versions of the periodic table.<sup id="cite_ref-Jensen_198-1" class="reference"><a href="#cite_note-Jensen-198"><span class="cite-bracket">[</span>180<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Papers_306-0" class="reference"><a href="#cite_note-Papers-306"><span class="cite-bracket">[</span>285<span class="cite-bracket">]</span></a></sup> Many forms retain the rectangular structure, including <a href="/wiki/Charles_Janet" title="Charles Janet">Charles Janet</a>'s left-step periodic table (pictured below), and the modernised form of Mendeleev's original 8-column layout that is still common in Russia. Other periodic table formats have been shaped much more exotically, such as spirals (<a href="/wiki/Otto_Theodor_Benfey" title="Otto Theodor Benfey">Otto Theodor Benfey</a>'s pictured to the right), circles and triangles.<sup id="cite_ref-307" class="reference"><a href="#cite_note-307"><span class="cite-bracket">[</span>286<span class="cite-bracket">]</span></a></sup> </p><p>Alternative periodic tables are often developed to highlight or emphasize chemical or physical properties of the elements that are not as apparent in traditional periodic tables, with different ones skewed more towards emphasizing chemistry or physics at either end.<sup id="cite_ref-Scerri402_308-0" class="reference"><a href="#cite_note-Scerri402-308"><span class="cite-bracket">[</span>287<span class="cite-bracket">]</span></a></sup> The standard form, which remains by far the most common, is somewhere in the middle.<sup id="cite_ref-Scerri402_308-1" class="reference"><a href="#cite_note-Scerri402-308"><span class="cite-bracket">[</span>287<span class="cite-bracket">]</span></a></sup> </p><p>The many different forms of the periodic table have prompted the questions of whether there is an optimal or definitive form of the periodic table, and if so, what it might be. There are no current consensus answers to either question.<sup id="cite_ref-sesqui_309-0" class="reference"><a href="#cite_note-sesqui-309"><span class="cite-bracket">[</span>288<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Scerri402_308-2" class="reference"><a href="#cite_note-Scerri402-308"><span class="cite-bracket">[</span>287<span class="cite-bracket">]</span></a></sup> Janet's left-step table is being increasingly discussed as a candidate for being the optimal or most fundamental form; Scerri has written in support of it, as it clarifies helium's nature as an s-block element, increases regularity by having all period lengths repeated, faithfully follows Madelung's rule by making each period correspond to one value of <span class="texhtml mvar" style="font-style:italic;">n</span> + <span class="texhtml">ℓ</span>,<sup id="cite_ref-lowdin_56-1" class="reference"><a href="#cite_note-lowdin-56"><span class="cite-bracket">[</span>g<span class="cite-bracket">]</span></a></sup> and regularises atomic number triads and the first-row anomaly trend. While he notes that its placement of helium atop the alkaline earth metals can be seen a disadvantage from a chemical perspective, he counters this by appealing to the first-row anomaly, pointing out that the periodic table "fundamentally reduces to quantum mechanics", and that it is concerned with "abstract elements" and hence atomic properties rather than macroscopic properties.<sup id="cite_ref-315" class="reference"><a href="#cite_note-315"><span class="cite-bracket">[</span>294<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-collapsible uncollapsed" style="background:#f8f8f8; font-size:90%; border:1px solid #a9a9a9; width:100%; max-width:1800px; margin:0 auto; padding:2px; vertical-align:top;"> <div style="background:#d8d8d8; padding:2px 4px;font-weight:bold; text-align:center;"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-collapse navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Periodic_table_(left_step)" title="Template:Periodic table (left step)"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Periodic_table_(left_step)" title="Template talk:Periodic table (left step)"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Periodic_table_(left_step)" title="Special:EditPage/Template:Periodic table (left step)"><abbr title="Edit this template">e</abbr></a></li></ul></div><div class="navbar-ct-mini"><a href="/wiki/Left-step_periodic_table" class="mw-redirect" title="Left-step periodic table">Left-step periodic table</a> (by Charles Janet)</div></div><div class="mw-collapsible-content"> <table style="border-spacing:1px;display:block;overflow:auto;width:100%; text-align:center;border-collapse:separate!important;margin:0 0 0.5em 0!important;"> <tbody><tr style="background:#e8e8e8"> <td> </td> <td> </td> <td><a href="/wiki/F-block" class="mw-redirect" title="F-block">f<sup>1</sup></a> </td> <td>f<sup>2</sup> </td> <td>f<sup>3</sup> </td> <td>f<sup>4</sup> </td> <td>f<sup>5</sup> </td> <td>f<sup>6</sup> </td> <td>f<sup>7</sup> </td> <td>f<sup>8</sup> </td> <td>f<sup>9</sup> </td> <td>f<sup>10</sup> </td> <td>f<sup>11</sup> </td> <td>f<sup>12</sup> </td> <td>f<sup>13</sup> </td> <td>f<sup>14</sup> </td> <td><a href="/wiki/D-block" class="mw-redirect" title="D-block">d<sup>1</sup></a> </td> <td>d<sup>2</sup> </td> <td>d<sup>3</sup> </td> <td>d<sup>4</sup> </td> <td>d<sup>5</sup> </td> <td>d<sup>6</sup> </td> <td>d<sup>7</sup> </td> <td>d<sup>8</sup> </td> <td>d<sup>9</sup> </td> <td>d<sup>10</sup> </td> <td><a href="/wiki/P-block" class="mw-redirect" title="P-block">p<sup>1</sup></a> </td> <td>p<sup>2</sup> </td> <td>p<sup>3</sup> </td> <td>p<sup>4</sup> </td> <td>p<sup>5</sup> </td> <td>p<sup>6</sup> </td> <td><a href="/wiki/S-block" class="mw-redirect" title="S-block">s<sup>1</sup></a> </td> <td>s<sup>2</sup> </td></tr> <tr> <td style="text-align:right; padding-right:2px;"><span style="background:#ff9999; display:inline-block;">1s</span> </td> <td> </td> <td colspan="30"> </td> <td style="background:#ff9999"><a href="/wiki/Hydrogen" title="Hydrogen">H</a> </td> <td style="background:#ff9999"><a href="/wiki/Helium" title="Helium">He</a> </td></tr> <tr> <td style="text-align:right; padding-right:2px;"><span style="background:#ff9999; display:inline-block;">2s</span> </td> <td> </td> <td colspan="30"> </td> <td style="background:#ff9999"><a href="/wiki/Lithium" title="Lithium">Li</a> </td> <td style="background:#ff9999"><a href="/wiki/Beryllium" title="Beryllium">Be</a> </td></tr> <tr> <td style="text-align:right; padding-right:2px;"><span style="background:#fdff8c; display:inline-block;">2p</span> <span style="background:#ff9999; display:inline-block;">3s</span> </td> <td> </td> <td colspan="24"> </td> <td style="background:#fdff8c"><a href="/wiki/Boron" title="Boron">B</a> </td> <td style="background:#fdff8c"><a href="/wiki/Carbon" title="Carbon">C</a> </td> <td style="background:#fdff8c"><a href="/wiki/Nitrogen" title="Nitrogen">N</a> </td> <td style="background:#fdff8c"><a href="/wiki/Oxygen" title="Oxygen">O</a> </td> <td style="background:#fdff8c"><a href="/wiki/Fluorine" title="Fluorine">F</a> </td> <td style="background:#fdff8c"><a href="/wiki/Neon" title="Neon">Ne</a> </td> <td style="background:#ff9999"><a href="/wiki/Sodium" title="Sodium">Na</a> </td> <td style="background:#ff9999"><a href="/wiki/Magnesium" title="Magnesium">Mg</a> </td></tr> <tr> <td style="text-align:right; padding-right:2px;"><span style="background:#fdff8c; display:inline-block;">3p</span> <span style="background:#ff9999; display:inline-block;">4s</span> </td> <td> </td> <td colspan="24"> </td> <td style="background:#fdff8c"><a href="/wiki/Aluminium" title="Aluminium">Al</a> </td> <td style="background:#fdff8c"><a href="/wiki/Silicon" title="Silicon">Si</a> </td> <td style="background:#fdff8c"><a href="/wiki/Phosphorus" title="Phosphorus">P</a> </td> <td style="background:#fdff8c"><a href="/wiki/Sulfur" title="Sulfur">S</a> </td> <td style="background:#fdff8c"><a href="/wiki/Chlorine" title="Chlorine">Cl</a> </td> <td style="background:#fdff8c"><a href="/wiki/Argon" title="Argon">Ar</a> </td> <td style="background:#ff9999"><a href="/wiki/Potassium" title="Potassium">K</a> </td> <td style="background:#ff9999"><a href="/wiki/Calcium" title="Calcium">Ca</a> </td></tr> <tr> <td style="text-align:right; padding-right:2px;"><span style="background:#99ccff; display:inline-block;">3d</span> <span style="background:#fdff8c; display:inline-block;">4p</span> <span style="background:#ff9999; display:inline-block;">5s</span> </td> <td> </td> <td colspan="14"> </td> <td style="background:#99ccff"><a href="/wiki/Scandium" title="Scandium">Sc</a> </td> <td style="background:#99ccff"><a href="/wiki/Titanium" title="Titanium">Ti</a> </td> <td style="background:#99ccff"><a href="/wiki/Vanadium" title="Vanadium">V</a> </td> <td style="background:#99ccff"><a href="/wiki/Chromium" title="Chromium">Cr</a> </td> <td style="background:#99ccff"><a href="/wiki/Manganese" title="Manganese">Mn</a> </td> <td style="background:#99ccff"><a href="/wiki/Iron" title="Iron">Fe</a> </td> <td style="background:#99ccff"><a href="/wiki/Cobalt" title="Cobalt">Co</a> </td> <td style="background:#99ccff"><a href="/wiki/Nickel" title="Nickel">Ni</a> </td> <td style="background:#99ccff"><a href="/wiki/Copper" title="Copper">Cu</a> </td> <td style="background:#99ccff"><a href="/wiki/Zinc" title="Zinc">Zn</a> </td> <td style="background:#fdff8c"><a href="/wiki/Gallium" title="Gallium">Ga</a> </td> <td style="background:#fdff8c"><a href="/wiki/Germanium" title="Germanium">Ge</a> </td> <td style="background:#fdff8c"><a href="/wiki/Arsenic" title="Arsenic">As</a> </td> <td style="background:#fdff8c"><a href="/wiki/Selenium" title="Selenium">Se</a> </td> <td style="background:#fdff8c"><a href="/wiki/Bromine" title="Bromine">Br</a> </td> <td style="background:#fdff8c"><a href="/wiki/Krypton" title="Krypton">Kr</a> </td> <td style="background:#ff9999"><a href="/wiki/Rubidium" title="Rubidium">Rb</a> </td> <td style="background:#ff9999"><a href="/wiki/Strontium" title="Strontium">Sr</a> </td></tr> <tr> <td style="text-align:right; padding-right:2px;"><span style="background:#99ccff; display:inline-block;">4d</span> <span style="background:#fdff8c; display:inline-block;">5p</span> <span style="background:#ff9999; display:inline-block;">6s</span> </td> <td> </td> <td colspan="14"> </td> <td style="background:#99ccff"><a href="/wiki/Yttrium" title="Yttrium">Y</a> </td> <td style="background:#99ccff"><a href="/wiki/Zirconium" title="Zirconium">Zr</a> </td> <td style="background:#99ccff"><a href="/wiki/Niobium" title="Niobium">Nb</a> </td> <td style="background:#99ccff"><a href="/wiki/Molybdenum" title="Molybdenum">Mo</a> </td> <td style="background:#99ccff"><a href="/wiki/Technetium" title="Technetium">Tc</a> </td> <td style="background:#99ccff"><a href="/wiki/Ruthenium" title="Ruthenium">Ru</a> </td> <td style="background:#99ccff"><a href="/wiki/Rhodium" title="Rhodium">Rh</a> </td> <td style="background:#99ccff"><a href="/wiki/Palladium" title="Palladium">Pd</a> </td> <td style="background:#99ccff"><a href="/wiki/Silver" title="Silver">Ag</a> </td> <td style="background:#99ccff"><a href="/wiki/Cadmium" title="Cadmium">Cd</a> </td> <td style="background:#fdff8c"><a href="/wiki/Indium" title="Indium">In</a> </td> <td style="background:#fdff8c"><a href="/wiki/Tin" title="Tin">Sn</a> </td> <td style="background:#fdff8c"><a href="/wiki/Antimony" title="Antimony">Sb</a> </td> <td style="background:#fdff8c"><a href="/wiki/Tellurium" title="Tellurium">Te</a> </td> <td style="background:#fdff8c"><a href="/wiki/Iodine" title="Iodine"> I </a> </td> <td style="background:#fdff8c"><a href="/wiki/Xenon" title="Xenon">Xe</a> </td> <td style="background:#ff9999"><a href="/wiki/Caesium" title="Caesium">Cs</a> </td> <td style="background:#ff9999"><a href="/wiki/Barium" title="Barium">Ba</a> </td></tr> <tr> <td width="3%" style="text-align:right; padding-right:2px;"><span class="nowrap"><span style="background:#9bff99; display:inline-block;">4f</span> <span style="background:#99ccff; display:inline-block;">5d</span> <span style="background:#fdff8c; display:inline-block;">6p</span> <span style="background:#ff9999; display:inline-block;">7s</span></span> </td> <td width="1%"> </td> <td width="3%" style="background:#9bff99"><a href="/wiki/Lanthanum" title="Lanthanum">La</a> </td> <td width="3%" style="background:#9bff99"><a href="/wiki/Cerium" title="Cerium">Ce</a> </td> <td width="3%" style="background:#9bff99"><a href="/wiki/Praseodymium" title="Praseodymium">Pr</a> </td> <td width="3%" style="background:#9bff99"><a href="/wiki/Neodymium" title="Neodymium">Nd</a> </td> <td width="3%" style="background:#9bff99"><a href="/wiki/Promethium" title="Promethium">Pm</a> </td> <td width="3%" style="background:#9bff99"><a href="/wiki/Samarium" title="Samarium">Sm</a> </td> <td width="3%" style="background:#9bff99"><a href="/wiki/Europium" title="Europium">Eu</a> </td> <td width="3%" style="background:#9bff99"><a href="/wiki/Gadolinium" title="Gadolinium">Gd</a> </td> <td width="3%" style="background:#9bff99"><a href="/wiki/Terbium" title="Terbium">Tb</a> </td> <td width="3%" style="background:#9bff99"><a href="/wiki/Dysprosium" title="Dysprosium">Dy</a> </td> <td width="3%" style="background:#9bff99"><a href="/wiki/Holmium" title="Holmium">Ho</a> </td> <td width="3%" style="background:#9bff99"><a href="/wiki/Erbium" title="Erbium">Er</a> </td> <td width="3%" style="background:#9bff99"><a href="/wiki/Thulium" title="Thulium">Tm</a> </td> <td width="3%" style="background:#9bff99"><a href="/wiki/Ytterbium" title="Ytterbium">Yb</a> </td> <td width="3%" style="background:#99ccff"><a href="/wiki/Lutetium" title="Lutetium">Lu</a> </td> <td width="3%" style="background:#99ccff"><a href="/wiki/Hafnium" title="Hafnium">Hf</a> </td> <td width="3%" style="background:#99ccff"><a href="/wiki/Tantalum" title="Tantalum">Ta</a> </td> <td width="3%" style="background:#99ccff"><a href="/wiki/Tungsten" title="Tungsten">W</a> </td> <td width="3%" style="background:#99ccff"><a href="/wiki/Rhenium" title="Rhenium">Re</a> </td> <td width="3%" style="background:#99ccff"><a href="/wiki/Osmium" title="Osmium">Os</a> </td> <td width="3%" style="background:#99ccff"><a href="/wiki/Iridium" title="Iridium">Ir</a> </td> <td width="3%" style="background:#99ccff"><a href="/wiki/Platinum" title="Platinum">Pt</a> </td> <td width="3%" style="background:#99ccff"><a href="/wiki/Gold" title="Gold">Au</a> </td> <td width="3%" style="background:#99ccff"><a href="/wiki/Mercury_(element)" title="Mercury (element)">Hg</a> </td> <td width="3%" style="background:#fdff8c"><a href="/wiki/Thallium" title="Thallium">Tl</a> </td> <td width="3%" style="background:#fdff8c"><a href="/wiki/Lead" title="Lead">Pb</a> </td> <td width="3%" style="background:#fdff8c"><a href="/wiki/Bismuth" title="Bismuth">Bi</a> </td> <td width="3%" style="background:#fdff8c"><a href="/wiki/Polonium" title="Polonium">Po</a> </td> <td width="3%" style="background:#fdff8c"><a href="/wiki/Astatine" title="Astatine">At</a> </td> <td width="3%" style="background:#fdff8c"><a href="/wiki/Radon" title="Radon">Rn</a> </td> <td width="3%" style="background:#ff9999"><a href="/wiki/Francium" title="Francium">Fr</a> </td> <td width="3%" style="background:#ff9999"><a href="/wiki/Radium" title="Radium">Ra</a> </td></tr> <tr> <td style="text-align:right; padding-right:2px;"><span class="nowrap"><span style="background:#9bff99; display:inline-block;">5f</span> <span style="background:#99ccff; display:inline-block;">6d</span> <span style="background:#fdff8c; display:inline-block;">7p</span> <span style="background:#ff9999; display:inline-block;">8s</span></span> </td> <td> </td> <td style="background:#9bff99"><a href="/wiki/Actinium" title="Actinium">Ac</a> </td> <td style="background:#9bff99"><a href="/wiki/Thorium" title="Thorium">Th</a> </td> <td style="background:#9bff99"><a href="/wiki/Protactinium" title="Protactinium">Pa</a> </td> <td style="background:#9bff99"><a href="/wiki/Uranium" title="Uranium">U</a> </td> <td style="background:#9bff99"><a href="/wiki/Neptunium" title="Neptunium">Np</a> </td> <td style="background:#9bff99"><a href="/wiki/Plutonium" title="Plutonium">Pu</a> </td> <td style="background:#9bff99"><a href="/wiki/Americium" title="Americium">Am</a> </td> <td style="background:#9bff99"><a href="/wiki/Curium" title="Curium">Cm</a> </td> <td style="background:#9bff99"><a href="/wiki/Berkelium" title="Berkelium">Bk</a> </td> <td style="background:#9bff99"><a href="/wiki/Californium" title="Californium">Cf</a> </td> <td style="background:#9bff99"><a href="/wiki/Einsteinium" title="Einsteinium">Es</a> </td> <td style="background:#9bff99"><a href="/wiki/Fermium" title="Fermium">Fm</a> </td> <td style="background:#9bff99"><a href="/wiki/Mendelevium" title="Mendelevium">Md</a> </td> <td style="background:#9bff99"><a href="/wiki/Nobelium" title="Nobelium">No</a> </td> <td style="background:#99ccff"><a href="/wiki/Lawrencium" title="Lawrencium">Lr</a> </td> <td style="background:#99ccff"><a href="/wiki/Rutherfordium" title="Rutherfordium">Rf</a> </td> <td style="background:#99ccff"><a href="/wiki/Dubnium" title="Dubnium">Db</a> </td> <td style="background:#99ccff"><a href="/wiki/Seaborgium" title="Seaborgium">Sg</a> </td> <td style="background:#99ccff"><a href="/wiki/Bohrium" title="Bohrium">Bh</a> </td> <td style="background:#99ccff"><a href="/wiki/Hassium" title="Hassium">Hs</a> </td> <td style="background:#99ccff"><a href="/wiki/Meitnerium" title="Meitnerium">Mt</a> </td> <td style="background:#99ccff"><a href="/wiki/Darmstadtium" title="Darmstadtium">Ds</a> </td> <td style="background:#99ccff"><a href="/wiki/Roentgenium" title="Roentgenium">Rg</a> </td> <td style="background:#99ccff"><a href="/wiki/Copernicium" title="Copernicium">Cn</a> </td> <td style="background:#fdff8c"><a href="/wiki/Nihonium" title="Nihonium">Nh</a> </td> <td style="background:#fdff8c"><a href="/wiki/Flerovium" title="Flerovium">Fl</a> </td> <td style="background:#fdff8c"><a href="/wiki/Moscovium" title="Moscovium">Mc</a> </td> <td style="background:#fdff8c"><a href="/wiki/Livermorium" title="Livermorium">Lv</a> </td> <td style="background:#fdff8c"><a href="/wiki/Tennessine" title="Tennessine">Ts</a> </td> <td style="background:#fdff8c"><a href="/wiki/Oganesson" title="Oganesson">Og</a> </td> <td style="background:#ff9999"><a href="/wiki/Ununennium" title="Ununennium">Uue</a> </td> <td style="background:#ff9999"><a href="/wiki/Unbinilium" title="Unbinilium">Ubn</a> </td></tr> <tr> <td> </td> <td> </td> <td colspan="33" style="height:7px; border-bottom:1px solid black"> </td></tr> <tr style="font-size:90%; line-height:100%;"> <td> </td> <td> </td> <td colspan="14" style="background:#9bff99"><a href="/wiki/F-block" class="mw-redirect" title="F-block">f-block</a> </td> <td colspan="10" style="background:#99ccff"><a href="/wiki/D-block" class="mw-redirect" title="D-block">d-block</a> </td> <td colspan="6" style="background:#fdff8c"><a href="/wiki/P-block" class="mw-redirect" title="P-block">p-block</a> </td> <td colspan="2" style="background:#ff9999"><a href="/wiki/S-block" class="mw-redirect" title="S-block">s-block</a> </td></tr></tbody></table> This form of periodic table is congruent with the order in which electron shells are ideally filled according to the <a href="/wiki/Aufbau_principle#Madelung_energy_ordering_rule" title="Aufbau principle">Madelung rule</a>, as shown in the accompanying sequence in the left margin (read from top to bottom, left to right). The experimentally determined ground-state electron configurations of the elements differ from the configurations predicted by the Madelung rule in twenty instances, but the Madelung-predicted configurations are always at least close to the ground state. The last two elements shown, elements 119 and 120, have not yet been synthesized.</div></div> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2></div> <ul><li><a href="/wiki/Nucleosynthesis" title="Nucleosynthesis">Nucleosynthesis</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="Notes">Notes</h2></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-lower-alpha"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-transuranium-1"><span class="mw-cite-backlink">^ <a href="#cite_ref-transuranium_1-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-transuranium_1-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">The question of how many natural elements there are is quite complicated and is not fully resolved. The heaviest element that occurs in large quantities on Earth is element 92, <a href="/wiki/Uranium" title="Uranium">uranium</a>. However, uranium can undergo <a href="/wiki/Spontaneous_fission" title="Spontaneous fission">spontaneous fission</a> in nature, and the resulting neutrons can strike other uranium atoms. If neutron capture then occurs, elements 93 and 94, <a href="/wiki/Neptunium" title="Neptunium">neptunium</a> and <a href="/wiki/Plutonium" title="Plutonium">plutonium</a>, are formed via <a href="/wiki/Beta_decay" title="Beta decay">beta decay</a>;<sup id="cite_ref-ThorntonBurdette_11-1" class="reference"><a href="#cite_note-ThorntonBurdette-11"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> these are in fact more common than some of the rarest elements in the first 92, such as <a href="/wiki/Promethium" title="Promethium">promethium</a>, <a href="/wiki/Astatine" title="Astatine">astatine</a>, and <a href="/wiki/Francium" title="Francium">francium</a> (see <a href="/wiki/Abundance_of_elements_in_Earth%27s_crust" title="Abundance of elements in Earth's crust">Abundance of elements in Earth's crust</a>). Theoretically, neutron capture on the resulting plutonium might produce even higher-numbered elements, but the quantities would be too small to be observed.<sup id="cite_ref-ThorntonBurdette_11-2" class="reference"><a href="#cite_note-ThorntonBurdette-11"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> In the early Solar System, shorter-lived elements had not yet decayed away, and consequently there were more than 94 naturally occurring elements. <a href="/wiki/Curium" title="Curium">Curium</a> (element 96) is the longest-lived element beyond the first 94, and is probably still being brought to Earth via <a href="/wiki/Cosmic_ray" title="Cosmic ray">cosmic rays</a>, but it has not been found.<sup id="cite_ref-ThorntonBurdette_11-3" class="reference"><a href="#cite_note-ThorntonBurdette-11"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> Elements up to 99 (<a href="/wiki/Einsteinium" title="Einsteinium">einsteinium</a>) have been observed in <a href="/wiki/Przybylski%27s_Star" title="Przybylski's Star">Przybylski's Star</a>.<sup id="cite_ref-gopka08_12-0" class="reference"><a href="#cite_note-gopka08-12"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> Elements up to 100 (<a href="/wiki/Fermium" title="Fermium">fermium</a>) probably occurred in the <a href="/wiki/Natural_nuclear_fission_reactor" title="Natural nuclear fission reactor">natural nuclear fission reactor</a> at <a href="/wiki/Oklo_Mine" class="mw-redirect" title="Oklo Mine">Oklo Mine</a>, <a href="/wiki/Gabon" title="Gabon">Gabon</a>, but they have long since decayed away.<sup id="cite_ref-emsley_13-0" class="reference"><a href="#cite_note-emsley-13"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> Even heavier elements may be produced in the <a href="/wiki/R-process" title="R-process">r-process</a> via <a href="/wiki/Supernova" title="Supernova">supernovae</a> or <a href="/wiki/Neutron_star_merger" title="Neutron star merger">neutron star mergers</a>, but this has not been confirmed. It is not clear how far they would extend past 100 and how long they would last: calculations suggest that nuclides of mass number around 280 to 290 are formed in the r-process, but quickly <a href="/wiki/Beta_decay" title="Beta decay">beta decay</a> to nuclides that suffer <a href="/wiki/Spontaneous_fission" title="Spontaneous fission">spontaneous fission</a>, so that 99.9% of the produced <a href="/wiki/Superheavy_element" title="Superheavy element">superheavy</a> nuclides would decay within a month.<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> If instead they were sufficiently long-lived, they might similarly be brought to Earth via cosmic rays, but again none have been found.<sup id="cite_ref-ThorntonBurdette_11-4" class="reference"><a href="#cite_note-ThorntonBurdette-11"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup></span> </li> <li id="cite_note-19"><span class="mw-cite-backlink"><b><a href="#cite_ref-19">^</a></b></span> <span class="reference-text">Some isotopes currently considered stable are theoretically expected to be radioactive with extremely long half-lives: for instance, all the stable isotopes of elements 62 (<a href="/wiki/Samarium" title="Samarium">samarium</a>), 63 (<a href="/wiki/Europium" title="Europium">europium</a>), and all elements from 67 (<a href="/wiki/Holmium" title="Holmium">holmium</a>) onward are expected to undergo <a href="/wiki/Alpha_decay" title="Alpha decay">alpha decay</a> or <a href="/wiki/Double_beta_decay" title="Double beta decay">double beta decay</a>. However, the predicted half-lives are extremely long (e.g. the alpha decay of <sup>208</sup>Pb to the ground state of <sup>204</sup>Hg is expected to have a half-life greater than 10<sup>120</sup> years), and the decays have never been observed.<sup id="cite_ref-bellidecay_17-0" class="reference"><a href="#cite_note-bellidecay-17"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Tretyak2002_18-0" class="reference"><a href="#cite_note-Tretyak2002-18"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup></span> </li> <li id="cite_note-23"><span class="mw-cite-backlink"><b><a href="#cite_ref-23">^</a></b></span> <span class="reference-text">The half-life of <a href="/wiki/Plutonium" title="Plutonium">plutonium</a>'s most stable isotope is just long enough that it should also be a primordial element. A 1971 study claimed to have detected primordial plutonium,<sup id="cite_ref-PU244_20-0" class="reference"><a href="#cite_note-PU244-20"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> but a more recent study from 2012 could not detect it.<sup id="cite_ref-PRC_21-0" class="reference"><a href="#cite_note-PRC-21"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> Based on its likely initial abundance in the Solar System, present experiments as of 2022 are likely about an order of magnitude away from detecting live primordial <sup>244</sup>Pu.<sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup></span> </li> <li id="cite_note-25"><span class="mw-cite-backlink"><b><a href="#cite_ref-25">^</a></b></span> <span class="reference-text">Tiny traces of plutonium are also continually brought to Earth via cosmic rays.<sup id="cite_ref-WallnerFaestermann2015_24-0" class="reference"><a href="#cite_note-WallnerFaestermann2015-24"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup></span> </li> <li id="cite_note-40"><span class="mw-cite-backlink"><b><a href="#cite_ref-40">^</a></b></span> <span class="reference-text">See for example <a rel="nofollow" class="external text" href="https://www.sigmaaldrich.com/SG/en/product/aldrich/z543209">the periodic table poster sold by Sigma-Aldrich.</a></span> </li> <li id="cite_note-47"><span class="mw-cite-backlink"><b><a href="#cite_ref-47">^</a></b></span> <span class="reference-text">Strictly speaking, one cannot draw an orbital such that the electron is guaranteed to be inside it, but it can be drawn to guarantee a 90% probability of this for example.<sup id="cite_ref-46" class="reference"><a href="#cite_note-46"><span class="cite-bracket">[</span>41<span class="cite-bracket">]</span></a></sup></span> </li> <li id="cite_note-lowdin-56"><span class="mw-cite-backlink">^ <a href="#cite_ref-lowdin_56-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-lowdin_56-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">Authors differ on whether the <span class="texhtml mvar" style="font-style:italic;">n</span> + <span class="texhtml">ℓ</span> rule has yet been derived from quantum mechanics. Scerri claims that it has not,<sup id="cite_ref-310" class="reference"><a href="#cite_note-310"><span class="cite-bracket">[</span>289<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-311" class="reference"><a href="#cite_note-311"><span class="cite-bracket">[</span>290<span class="cite-bracket">]</span></a></sup> despite several attempts to do so.<sup id="cite_ref-312" class="reference"><a href="#cite_note-312"><span class="cite-bracket">[</span>291<span class="cite-bracket">]</span></a></sup> On the other hand, Ostrovsky, who has claimed such justification from 1971, wrote 'Some authors insist that "still nobody has deduced the n+l rule from the principles of quantum mechanics", while others present quantum justification of the rule that was not ever disputed.'<sup id="cite_ref-313" class="reference"><a href="#cite_note-313"><span class="cite-bracket">[</span>292<span class="cite-bracket">]</span></a></sup> Other authors argue that such a derivation is not necessary, because it admits exceptions.<sup id="cite_ref-314" class="reference"><a href="#cite_note-314"><span class="cite-bracket">[</span>293<span class="cite-bracket">]</span></a></sup></span> </li> <li id="cite_note-65"><span class="mw-cite-backlink"><b><a href="#cite_ref-65">^</a></b></span> <span class="reference-text"> Once two to four electrons are removed, the d and f orbitals usually become lower in energy than the s ones:<sup id="cite_ref-Jorgensen_59-1" class="reference"><a href="#cite_note-Jorgensen-59"><span class="cite-bracket">[</span>52<span class="cite-bracket">]</span></a></sup> <dl><dd>1s ≪ 2s < 2p ≪ 3s < 3p ≪ 3d < 4s < 4p ≪ 4d < 5s < 5p ≪ 4f < 5d < 6s < 6p ≪ 5f < 6d < 7s < 7p ≪ ...</dd></dl> and in the limit for extremely highly charged ions, orbitals simply fill in the order of increasing <i>n</i> instead. There is a gradual transition between the limiting situations of highly charged ions (increasing <i>n</i>) and neutral atoms (Madelung's rule).<sup id="cite_ref-Goudsmit_51-2" class="reference"><a href="#cite_note-Goudsmit-51"><span class="cite-bracket">[</span>45<span class="cite-bracket">]</span></a></sup> Thus for example, the energy order for the 55th electron outside the xenon core proceeds as follows in the isoelectronic series of caesium (55 electrons):<sup id="cite_ref-elyashevich_60-0" class="reference"><a href="#cite_note-elyashevich-60"><span class="cite-bracket">[</span>53<span class="cite-bracket">]</span></a></sup> <dl><dd>Cs<sup>0</sup>: 6s < 6p < 5d < 7s < 4f</dd> <dd>Ba<sup>+</sup>: 6s < 5d < 6p < 7s < 4f</dd> <dd>La<sup>2+</sup>: 5d < 4f < 6s < 6p < 7s</dd> <dd>Ce<sup>3+</sup>: 4f < 5d < 6s < 6p < 7s</dd></dl> and in the isoelectronic series of holmium (67 electrons), a Ho<sup>0</sup> atom is [Xe]4f<sup>11</sup>6s<sup>2</sup>, but Er<sup>+</sup> is [Xe]4f<sup>12</sup>6s<sup>1</sup>, Tm<sup>2+</sup> through W<sup>7+</sup> are [Xe]4f<sup>13</sup>, and from Re<sup>8+</sup> onward the configuration is [Cd]4f<sup>14</sup>5p<sup>5</sup> following the hydrogenic order.<sup id="cite_ref-rareearths_61-0" class="reference"><a href="#cite_note-rareearths-61"><span class="cite-bracket">[</span>54<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-62" class="reference"><a href="#cite_note-62"><span class="cite-bracket">[</span>55<span class="cite-bracket">]</span></a></sup> <dl><dd></dd></dl> Also, the ordering of the orbitals between each ≪ changes somewhat throughout each period. For example, the ordering in argon and potassium is 3p ≪ 4s < 4p ≪ 3d; by calcium it has become 3p ≪ 4s < 3d < 4p; from scandium to copper it is 3p ≪ 3d < 4s < 4p; and from zinc to krypton it is 3p < 3d ≪ 4s < 4p<sup id="cite_ref-Cao_58-1" class="reference"><a href="#cite_note-Cao-58"><span class="cite-bracket">[</span>51<span class="cite-bracket">]</span></a></sup> as the d-orbitals fall into the core at gallium.<sup id="cite_ref-63" class="reference"><a href="#cite_note-63"><span class="cite-bracket">[</span>56<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-KW_64-0" class="reference"><a href="#cite_note-KW-64"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup> Deeply buried core shells in heavy atoms thus come closer to the hydrogenic order: around osmium (<i>Z</i> = 76) 4f falls below 5p, and around bismuth (<i>Z</i> = 83) 4f falls below 5s as well.<sup id="cite_ref-rareearths_61-1" class="reference"><a href="#cite_note-rareearths-61"><span class="cite-bracket">[</span>54<span class="cite-bracket">]</span></a></sup></span> </li> <li id="cite_note-68"><span class="mw-cite-backlink"><b><a href="#cite_ref-68">^</a></b></span> <span class="reference-text">In fact, electron configurations represent a first-order approximation: an atom really exists in a superposition of multiple configurations, and electrons in an atom are indistinguishable.<sup id="cite_ref-Scerri2009_32-1" class="reference"><a href="#cite_note-Scerri2009-32"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup> The elements in the d- and f-blocks have multiple configurations separated by small energies and can change configuration depending on the chemical environment.<sup id="cite_ref-Jorgensen_59-2" class="reference"><a href="#cite_note-Jorgensen-59"><span class="cite-bracket">[</span>52<span class="cite-bracket">]</span></a></sup> In some of the undiscovered g-block elements, mixing of configurations may become so important that the result can no longer be well-described by a single configuration.<sup id="cite_ref-nefedov_67-0" class="reference"><a href="#cite_note-nefedov-67"><span class="cite-bracket">[</span>59<span class="cite-bracket">]</span></a></sup></span> </li> <li id="cite_note-81"><span class="mw-cite-backlink"><b><a href="#cite_ref-81">^</a></b></span> <span class="reference-text">Compounds that would use the 6d orbitals of nihonium as valence orbitals have been theoretically investigated, but they are all expected to be too unstable to observe.<sup id="cite_ref-Seth_80-0" class="reference"><a href="#cite_note-Seth-80"><span class="cite-bracket">[</span>71<span class="cite-bracket">]</span></a></sup></span> </li> <li id="cite_note-133"><span class="mw-cite-backlink"><b><a href="#cite_ref-133">^</a></b></span> <span class="reference-text">Properties of the p-block elements nevertheless do affect the succeeding s-block elements. The 3s shell in sodium is above a kainosymmetric 2p core, but the 4s shell in potassium is above the much larger 3p core. Hence while one would have already expected potassium atoms to be larger than sodium atoms, the size difference is greater than usual.<sup id="cite_ref-SB23_106-4" class="reference"><a href="#cite_note-SB23-106"><span class="cite-bracket">[</span>96<span class="cite-bracket">]</span></a></sup></span> </li> <li id="cite_note-147"><span class="mw-cite-backlink"><b><a href="#cite_ref-147">^</a></b></span> <span class="reference-text">There are many lower oxides as well: for example, <a href="/wiki/Phosphorus" title="Phosphorus">phosphorus</a> in group 15 forms two oxides, <a href="/wiki/Phosphorus_trioxide" title="Phosphorus trioxide">P<sub>2</sub>O<sub>3</sub></a> and <a href="/wiki/Phosphorus_pentoxide" title="Phosphorus pentoxide">P<sub>2</sub>O<sub>5</sub></a>.<sup id="cite_ref-Greenwood27_123-1" class="reference"><a href="#cite_note-Greenwood27-123"><span class="cite-bracket">[</span>113<span class="cite-bracket">]</span></a></sup></span> </li> <li id="cite_note-153"><span class="mw-cite-backlink"><b><a href="#cite_ref-153">^</a></b></span> <span class="reference-text">The normally "forbidden" intermediate oxidation states may be stabilized by forming <a href="/wiki/Dimer_(chemistry)" class="mw-redirect" title="Dimer (chemistry)">dimers</a>, as in [Cl<sub>3</sub>Ga–GaCl<sub>3</sub>]<sup>2−</sup> (gallium in the +2 oxidation state) or <a href="/wiki/Disulfur_decafluoride" title="Disulfur decafluoride">S<sub>2</sub>F<sub>10</sub></a> (sulfur in the +5 oxidation state).<sup id="cite_ref-sb45_151-1" class="reference"><a href="#cite_note-sb45-151"><span class="cite-bracket">[</span>139<span class="cite-bracket">]</span></a></sup> Some compounds that appear to be in such intermediate oxidation states are actually mixed-valence compounds, such as <a href="/wiki/Antimony_tetroxide" title="Antimony tetroxide">Sb<sub>2</sub>O<sub>4</sub></a>, which contains both Sb(III) and Sb(V).<sup id="cite_ref-Amador_152-0" class="reference"><a href="#cite_note-Amador-152"><span class="cite-bracket">[</span>140<span class="cite-bracket">]</span></a></sup></span> </li> <li id="cite_note-164"><span class="mw-cite-backlink"><b><a href="#cite_ref-164">^</a></b></span> <span class="reference-text">The boundary between dispersion forces and metallic bonding is gradual, like that between ionic and covalent bonding. Characteristic metallic properties do not appear in small mercury clusters, but do appear in large ones.<sup id="cite_ref-163" class="reference"><a href="#cite_note-163"><span class="cite-bracket">[</span>150<span class="cite-bracket">]</span></a></sup></span> </li> <li id="cite_note-168"><span class="mw-cite-backlink"><b><a href="#cite_ref-168">^</a></b></span> <span class="reference-text">All this describes the situation at standard pressure. Under sufficiently high pressure, the band gaps of any solid drop to zero and metallization occurs. Thus for example at about 170 <a href="/wiki/Bar_(unit)" title="Bar (unit)">kbar</a> iodine becomes a metal,<sup id="cite_ref-Siekierski_165-4" class="reference"><a href="#cite_note-Siekierski-165"><span class="cite-bracket">[</span>151<span class="cite-bracket">]</span></a></sup> and <a href="/wiki/Metallic_hydrogen" title="Metallic hydrogen">metallic hydrogen</a> should form at pressures of about four million atmospheres.<sup id="cite_ref-167" class="reference"><a href="#cite_note-167"><span class="cite-bracket">[</span>153<span class="cite-bracket">]</span></a></sup> See <a href="/wiki/Metallization_pressure" title="Metallization pressure">metallization pressure</a> for values for all nonmetals.</span> </li> <li id="cite_note-180"><span class="mw-cite-backlink"><b><a href="#cite_ref-180">^</a></b></span> <span class="reference-text">Descriptions of the structures formed by the elements can be found throughout Greenwood and Earnshaw. There are two borderline cases. Arsenic's most stable form conducts electricity like a metal, but the bonding is significantly more localized to the nearest neighbours than it is for the similar structures of antimony and bismuth,<sup id="cite_ref-171" class="reference"><a href="#cite_note-171"><span class="cite-bracket">[</span>156<span class="cite-bracket">]</span></a></sup> and unlike normal metals it does not have a long liquid range, but rather sublimes instead. Hence its structure is better treated as network covalent.<sup id="cite_ref-172" class="reference"><a href="#cite_note-172"><span class="cite-bracket">[</span>157<span class="cite-bracket">]</span></a></sup> Carbon as <a href="/wiki/Graphite" title="Graphite">graphite</a> shows metallic conduction parallel to its planes, but is a semiconductor perpendicular to them. Some computations predict copernicium and flerovium to be nonmetallic,<sup id="cite_ref-CRNL_173-0" class="reference"><a href="#cite_note-CRNL-173"><span class="cite-bracket">[</span>158<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Florez_174-0" class="reference"><a href="#cite_note-Florez-174"><span class="cite-bracket">[</span>159<span class="cite-bracket">]</span></a></sup> but the most recent experiments on them suggest that they are metallic.<sup id="cite_ref-superheavy_175-0" class="reference"><a href="#cite_note-superheavy-175"><span class="cite-bracket">[</span>160<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Ingo_176-0" class="reference"><a href="#cite_note-Ingo-176"><span class="cite-bracket">[</span>161<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Yakushev_177-0" class="reference"><a href="#cite_note-Yakushev-177"><span class="cite-bracket">[</span>162<span class="cite-bracket">]</span></a></sup> Astatine is calculated to metallise at standard conditions,<sup id="cite_ref-Hermann_178-0" class="reference"><a href="#cite_note-Hermann-178"><span class="cite-bracket">[</span>163<span class="cite-bracket">]</span></a></sup> so presumably tennessine should as well.<sup id="cite_ref-179" class="reference"><a href="#cite_note-179"><span class="cite-bracket">[</span>164<span class="cite-bracket">]</span></a></sup></span> </li> <li id="cite_note-186"><span class="mw-cite-backlink"><b><a href="#cite_ref-186">^</a></b></span> <span class="reference-text">See <a href="/wiki/Melting_points_of_the_elements_(data_page)" title="Melting points of the elements (data page)">melting points of the elements (data page)</a>. The same is probably true of francium, but due to its extreme instability, this has never been experimentally confirmed. Copernicium and flerovium are expected to be liquids,<sup id="cite_ref-CRNL_173-1" class="reference"><a href="#cite_note-CRNL-173"><span class="cite-bracket">[</span>158<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Florez_174-1" class="reference"><a href="#cite_note-Florez-174"><span class="cite-bracket">[</span>159<span class="cite-bracket">]</span></a></sup> similar to mercury, and experimental evidence suggests that they are metals.<sup id="cite_ref-superheavy_175-1" class="reference"><a href="#cite_note-superheavy-175"><span class="cite-bracket">[</span>160<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Ingo_176-1" class="reference"><a href="#cite_note-Ingo-176"><span class="cite-bracket">[</span>161<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Yakushev_177-1" class="reference"><a href="#cite_note-Yakushev-177"><span class="cite-bracket">[</span>162<span class="cite-bracket">]</span></a></sup></span> </li> <li id="cite_note-metalloids-196"><span class="mw-cite-backlink">^ <a href="#cite_ref-metalloids_196-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-metalloids_196-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">See <a href="/wiki/Lists_of_metalloids" title="Lists of metalloids">lists of metalloids</a>. For example, a periodic table used by the American Chemical Society includes polonium as a metalloid,<sup id="cite_ref-ACS_192-0" class="reference"><a href="#cite_note-ACS-192"><span class="cite-bracket">[</span>175<span class="cite-bracket">]</span></a></sup> but one used by the Royal Society of Chemistry does not,<sup id="cite_ref-193" class="reference"><a href="#cite_note-193"><span class="cite-bracket">[</span>176<span class="cite-bracket">]</span></a></sup> and that included in the <i><a href="/wiki/Encyclop%C3%A6dia_Britannica" title="Encyclopædia Britannica">Encyclopædia Britannica</a></i> does not refer to metalloids or semi-metals at all.<sup id="cite_ref-EB_194-0" class="reference"><a href="#cite_note-EB-194"><span class="cite-bracket">[</span>177<span class="cite-bracket">]</span></a></sup> Classification can change even within a single work. For example, Sherwin and Weston's <i>Chemistry of the Non-Metallic Elements</i> (1966) has a periodic table on p. 7 classifying antimony as a nonmetal, but on p. 115 it is called a metal.<sup id="cite_ref-195" class="reference"><a href="#cite_note-195"><span class="cite-bracket">[</span>178<span class="cite-bracket">]</span></a></sup></span> </li> <li id="cite_note-260"><span class="mw-cite-backlink"><b><a href="#cite_ref-260">^</a></b></span> <span class="reference-text">Demkov and Ostrovsky consider the potential <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle U_{1/2}(r)=-{\frac {2v}{rR(r+R)^{2}}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>U</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> <mrow class="MJX-TeXAtom-ORD"> <mo>/</mo> </mrow> <mn>2</mn> </mrow> </msub> <mo stretchy="false">(</mo> <mi>r</mi> <mo stretchy="false">)</mo> <mo>=</mo> <mo>−<!-- − --></mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mn>2</mn> <mi>v</mi> </mrow> <mrow> <mi>r</mi> <mi>R</mi> <mo stretchy="false">(</mo> <mi>r</mi> <mo>+</mo> <mi>R</mi> <msup> <mo stretchy="false">)</mo> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msup> </mrow> </mfrac> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle U_{1/2}(r)=-{\frac {2v}{rR(r+R)^{2}}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/97b73d1f4601f3cf40f5dbffef041aa355758574" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.671ex; width:24.216ex; height:6.009ex;" alt="{\displaystyle U_{1/2}(r)=-{\frac {2v}{rR(r+R)^{2}}}}"></span> where <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle R}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>R</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle R}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/4b0bfb3769bf24d80e15374dc37b0441e2616e33" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.764ex; height:2.176ex;" alt="{\displaystyle R}"></span> and <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle v}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>v</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle v}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/e07b00e7fc0847fbd16391c778d65bc25c452597" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.128ex; height:1.676ex;" alt="{\displaystyle v}"></span> are constant parameters; this approaches a <a href="/wiki/Coulomb_potential" class="mw-redirect" title="Coulomb potential">Coulomb potential</a> for small <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle r}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>r</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle r}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/0d1ecb613aa2984f0576f70f86650b7c2a132538" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.049ex; height:1.676ex;" alt="{\displaystyle r}"></span>. When <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle v}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>v</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle v}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/e07b00e7fc0847fbd16391c778d65bc25c452597" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.128ex; height:1.676ex;" alt="{\displaystyle v}"></span> satisfies the condition <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle v=v_{N}={\frac {1}{4}}R^{2}N(N+1)}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>v</mi> <mo>=</mo> <msub> <mi>v</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>N</mi> </mrow> </msub> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mn>1</mn> <mn>4</mn> </mfrac> </mrow> <msup> <mi>R</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msup> <mi>N</mi> <mo stretchy="false">(</mo> <mi>N</mi> <mo>+</mo> <mn>1</mn> <mo stretchy="false">)</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle v=v_{N}={\frac {1}{4}}R^{2}N(N+1)}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/4895faf5a983c07b494d185e4ab69c9a30f13d2a" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.838ex; width:24.9ex; height:5.176ex;" alt="{\displaystyle v=v_{N}={\frac {1}{4}}R^{2}N(N+1)}"></span>, where <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle N=n+l}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>N</mi> <mo>=</mo> <mi>n</mi> <mo>+</mo> <mi>l</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle N=n+l}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/edb6ea36e4be42141a682796389802300761f1a6" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.505ex; width:10.09ex; height:2.343ex;" alt="{\displaystyle N=n+l}"></span>, the zero-energy solutions to the <a href="/wiki/Schr%C3%B6dinger_equation" title="Schrödinger equation">Schrödinger equation</a> for this potential can be described analytically with <a href="/wiki/Gegenbauer_polynomials" title="Gegenbauer polynomials">Gegenbauer polynomials</a>. As <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle v}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>v</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle v}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/e07b00e7fc0847fbd16391c778d65bc25c452597" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.128ex; height:1.676ex;" alt="{\displaystyle v}"></span> passes through each of these values, a manifold containing all states with that value of <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle N}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>N</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle N}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/f5e3890c981ae85503089652feb48b191b57aae3" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:2.064ex; height:2.176ex;" alt="{\displaystyle N}"></span> arises at zero energy and then becomes bound, recovering the Madelung order. Perturbation-theory considerations show that states with smaller <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle n}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>n</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle n}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/a601995d55609f2d9f5e233e36fbe9ea26011b3b" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.395ex; height:1.676ex;" alt="{\displaystyle n}"></span> have lower energy, and that the s-orbitals (with <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle l=0}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>l</mi> <mo>=</mo> <mn>0</mn> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle l=0}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/66485a3e3da13d226eb36a131bf1fc7e16403a5e" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:4.954ex; height:2.176ex;" alt="{\displaystyle l=0}"></span>) have their energies approaching the next <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle n+l}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>n</mi> <mo>+</mo> <mi>l</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle n+l}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/3c70a7ea5d7bb4061fd049ae0512c8bf954bb7e7" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.505ex; width:4.928ex; height:2.343ex;" alt="{\displaystyle n+l}"></span> group.<sup id="cite_ref-DO_259-1" class="reference"><a href="#cite_note-DO-259"><span class="cite-bracket">[</span>241<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-shattered_100-1" class="reference"><a href="#cite_note-shattered-100"><span class="cite-bracket">[</span>90<span class="cite-bracket">]</span></a></sup></span> </li> <li id="cite_note-261"><span class="mw-cite-backlink"><b><a href="#cite_ref-261">^</a></b></span> <span class="reference-text">For example, the early actinides continue to behave more like the d-block transition metals in their propensity towards high oxidation states all the way from actinium to uranium, even though it is actually only actinium and thorium that have d-block-like configurations in the gas phase; f-electrons appear already at protactinium.<sup id="cite_ref-johnson_120-4" class="reference"><a href="#cite_note-johnson-120"><span class="cite-bracket">[</span>110<span class="cite-bracket">]</span></a></sup> Uranium's actual configuration of [Rn]5f<sup>3</sup>6d<sup>1</sup>7s<sup>2</sup> is in fact analogous to that Hund assumed for the lanthanides, but uranium does not favour the trivalent state, preferring to be tetravalent or hexavalent.<sup id="cite_ref-rareearths_61-3" class="reference"><a href="#cite_note-rareearths-61"><span class="cite-bracket">[</span>54<span class="cite-bracket">]</span></a></sup> On the other hand, lanthanide-like configurations for the actinides begin at plutonium, but the shift towards lanthanide-like behaviour is only clear at curium: the elements between uranium and curium form a transition from transition-metal-like behaviour to lanthanide-like behaviour.<sup id="cite_ref-johnson_120-5" class="reference"><a href="#cite_note-johnson-120"><span class="cite-bracket">[</span>110<span class="cite-bracket">]</span></a></sup> Thus chemical behaviour and electron configuration do not exactly match each other.<sup id="cite_ref-johnson_120-6" class="reference"><a href="#cite_note-johnson-120"><span class="cite-bracket">[</span>110<span class="cite-bracket">]</span></a></sup></span> </li> <li id="cite_note-264"><span class="mw-cite-backlink"><b><a href="#cite_ref-264">^</a></b></span> <span class="reference-text">Technetium, promethium, astatine, neptunium, and plutonium were eventually discovered to occur in nature as well, albeit in tiny traces. See <a href="/wiki/Timeline_of_chemical_element_discoveries" class="mw-redirect" title="Timeline of chemical element discoveries">timeline of chemical element discoveries</a>.</span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="References">References</h2></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239543626"><div class="reflist reflist-columns references-column-width" style="column-width: 30em;"> <ol class="references"> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://iupac.org/what-we-do/periodic-table-of-elements/">"Periodic Table of Elements"</a>. <i>IUPAC | International Union of Pure and Applied Chemistry</i><span class="reference-accessdate">. Retrieved <span class="nowrap">11 May</span> 2024</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=IUPAC+%7C+International+Union+of+Pure+and+Applied+Chemistry&rft.atitle=Periodic+Table+of+Elements&rft_id=https%3A%2F%2Fiupac.org%2Fwhat-we-do%2Fperiodic-table-of-elements%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-CIAAW2013-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-CIAAW2013_3-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMeijaCoplenBerglundBrand2016" class="citation journal cs1">Meija, Juris; et al. 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(4 May 2022). <a rel="nofollow" class="external text" href="https://www.degruyter.com/document/doi/10.1515/pac-2019-0603/html">"Standard atomic weights of the elements 2021 (IUPAC Technical Report)"</a>. <i>Pure and Applied Chemistry</i>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1515%2Fpac-2019-0603">10.1515/pac-2019-0603</a>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1365-3075">1365-3075</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Pure+and+Applied+Chemistry&rft.atitle=Standard+atomic+weights+of+the+elements+2021+%28IUPAC+Technical+Report%29&rft.date=2022-05-04&rft_id=info%3Adoi%2F10.1515%2Fpac-2019-0603&rft.issn=1365-3075&rft.aulast=Prohaska&rft.aufirst=Thomas&rft.au=Irrgeher%2C+Johanna&rft.au=Benefield%2C+Jacqueline&rft.au=B%C3%B6hlke%2C+John+K.&rft.au=Chesson%2C+Lesley+A.&rft.au=Coplen%2C+Tyler+B.&rft.au=Ding%2C+Tiping&rft.au=Dunn%2C+Philip+J.+H.&rft.au=Gr%C3%B6ning%2C+Manfred&rft.au=Holden%2C+Norman+E.&rft.au=Meijer%2C+Harro+A.+J.&rft_id=https%3A%2F%2Fwww.degruyter.com%2Fdocument%2Fdoi%2F10.1515%2Fpac-2019-0603%2Fhtml&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-neutronium-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-neutronium_5-0">^</a></b></span> <span class="reference-text">An <a href="/wiki/Neutronium" title="Neutronium">element zero</a> (i.e. a substance composed purely of neutrons), is included in a few alternate presentations, for example, in the <a rel="nofollow" class="external text" href="https://www.meta-synthesis.com/webbook/35_pt/pt_database.php?PT_id=22">Chemical Galaxy</a>. See <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFLabarca2016" class="citation journal cs1">Labarca, M. (2016). "An element of atomic number zero?". <i>New Journal of Chemistry</i>. <b>40</b> (11): 9002–9006. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1039%2FC6NJ02076C">10.1039/C6NJ02076C</a>. <a href="/wiki/Hdl_(identifier)" class="mw-redirect" title="Hdl (identifier)">hdl</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://hdl.handle.net/11336%2F46854">11336/46854</a></span>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1144-0546">1144-0546</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=New+Journal+of+Chemistry&rft.atitle=An+element+of+atomic+number+zero%3F&rft.volume=40&rft.issue=11&rft.pages=9002-9006&rft.date=2016&rft_id=info%3Ahdl%2F11336%2F46854&rft.issn=1144-0546&rft_id=info%3Adoi%2F10.1039%2FC6NJ02076C&rft.aulast=Labarca&rft.aufirst=M.&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text"><a href="/wiki/International_Union_of_Pure_and_Applied_Chemistry" title="International Union of Pure and Applied Chemistry">IUPAC</a>, <i><a href="/wiki/IUPAC_books#Gold_Book" class="mw-redirect" title="IUPAC books">Compendium of Chemical Terminology</a></i>, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "<a rel="nofollow" class="external text" href="https://goldbook.iupac.org/terms/view/C01022.html">Chemical element</a>". <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1351%2Fgoldbook.C01022">10.1351/goldbook.C01022</a></span> </li> <li id="cite_note-IUPAC-redbook-7"><span class="mw-cite-backlink">^ <a href="#cite_ref-IUPAC-redbook_7-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-IUPAC-redbook_7-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-IUPAC-redbook_7-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-IUPAC-redbook_7-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-IUPAC-redbook_7-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-IUPAC-redbook_7-5"><sup><i><b>f</b></i></sup></a> <a href="#cite_ref-IUPAC-redbook_7-6"><sup><i><b>g</b></i></sup></a> <a href="#cite_ref-IUPAC-redbook_7-7"><sup><i><b>h</b></i></sup></a> <a href="#cite_ref-IUPAC-redbook_7-8"><sup><i><b>i</b></i></sup></a> <a href="#cite_ref-IUPAC-redbook_7-9"><sup><i><b>j</b></i></sup></a> <a href="#cite_ref-IUPAC-redbook_7-10"><sup><i><b>k</b></i></sup></a> <a href="#cite_ref-IUPAC-redbook_7-11"><sup><i><b>l</b></i></sup></a> <a href="#cite_ref-IUPAC-redbook_7-12"><sup><i><b>m</b></i></sup></a> <a href="#cite_ref-IUPAC-redbook_7-13"><sup><i><b>n</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://iupac.org/what-we-do/periodic-table-of-elements/">"Periodic Table of Elements"</a>. <i>iupac.org</i>. IUPAC. 2021. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20160410043726/https://iupac.org/what-we-do/periodic-table-of-elements/">Archived</a> from the original on 10 April 2016<span class="reference-accessdate">. Retrieved <span class="nowrap">3 April</span> 2021</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=iupac.org&rft.atitle=Periodic+Table+of+Elements&rft.date=2021&rft_id=https%3A%2F%2Fiupac.org%2Fwhat-we-do%2Fperiodic-table-of-elements%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-ciaaw-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-ciaaw_8-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.ciaaw.org/atomic-weights.htm">"Standard Atomic Weights"</a>. <i>Commission on Isotopic Abundances and Atomic Weights</i>. International Union of Pure and Applied Chemistry. 2019. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20200808155924/https://www.ciaaw.org/atomic-weights.htm">Archived</a> from the original on 8 August 2020<span class="reference-accessdate">. Retrieved <span class="nowrap">7 February</span> 2021</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Commission+on+Isotopic+Abundances+and+Atomic+Weights&rft.atitle=Standard+Atomic+Weights&rft.date=2019&rft_id=https%3A%2F%2Fwww.ciaaw.org%2Fatomic-weights.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-Greenwood-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-Greenwood_9-0">^</a></b></span> <span class="reference-text">Greenwood & Earnshaw, pp. 24–27</span> </li> <li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text">Gray, p. 6</span> </li> <li id="cite_note-ThorntonBurdette-11"><span class="mw-cite-backlink">^ <a href="#cite_ref-ThorntonBurdette_11-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-ThorntonBurdette_11-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-ThorntonBurdette_11-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-ThorntonBurdette_11-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-ThorntonBurdette_11-4"><sup><i><b>e</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFThorntonBurdette2019" class="citation journal cs1">Thornton, Brett F.; Burdette, Shawn C. 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Retrieved <span class="nowrap">19 February</span> 2022</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Nature+Chemistry&rft.atitle=Neutron+stardust+and+the+elements+of+Earth&rft.volume=11&rft.issue=1&rft.pages=4-10&rft.date=2019&rft_id=info%3Adoi%2F10.1038%2Fs41557-018-0190-9&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A54632815%23id-name%3DS2CID&rft_id=info%3Apmid%2F30552435&rft_id=info%3Abibcode%2F2019NatCh..11....4T&rft.aulast=Thornton&rft.aufirst=Brett+F.&rft.au=Burdette%2C+Shawn+C.&rft_id=https%3A%2F%2Fwww.nature.com%2Farticles%2Fs41557-018-0190-9&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-gopka08-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-gopka08_12-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFGopkaYushchenkoYushchenkoPanov2008" class="citation journal cs1">Gopka, V.F.; Yushchenko, A.V.; Yushchenko, V.A.; Panov, I.V.; Kim, Ch. 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Retrieved <span class="nowrap">30 July</span> 2016</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=The+constitution+of+group+3+of+the+periodic+table&rft.pub=IUPAC&rft.date=2015&rft_id=https%3A%2F%2Fiupac.org%2Fprojects%2Fproject-details%2F%3Fproject_nr%3D2015-039-2-200&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-Scerri17-41"><span class="mw-cite-backlink">^ <a href="#cite_ref-Scerri17_41-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Scerri17_41-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">Scerri, p. 17</span> </li> <li id="cite_note-42"><span class="mw-cite-backlink"><b><a href="#cite_ref-42">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.merriam-webster.com/dictionary/periodic%20law">"periodic law"</a>. <i><a href="/wiki/Merriam-Webster" title="Merriam-Webster">Merriam-Webster.com Dictionary</a></i>. 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Jensen">Jensen, William B.</a> (2009). <a rel="nofollow" class="external text" href="https://doi.org/10.1021%2Fed086p1186">"Misapplying the Periodic Law"</a>. <i>Journal of Chemical Education</i>. <b>86</b> (10): 1186. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2009JChEd..86.1186J">2009JChEd..86.1186J</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1021%2Fed086p1186">10.1021/ed086p1186</a></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+of+Chemical+Education&rft.atitle=Misapplying+the+Periodic+Law&rft.volume=86&rft.issue=10&rft.pages=1186&rft.date=2009&rft_id=info%3Adoi%2F10.1021%2Fed086p1186&rft_id=info%3Abibcode%2F2009JChEd..86.1186J&rft.aulast=Jensen&rft.aufirst=William+B.&rft_id=https%3A%2F%2Fdoi.org%2F10.1021%252Fed086p1186&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-FIII19-44"><span class="mw-cite-backlink">^ <a href="#cite_ref-FIII19_44-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-FIII19_44-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-FIII19_44-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-FIII19_44-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-FIII19_44-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-FIII19_44-5"><sup><i><b>f</b></i></sup></a> <a href="#cite_ref-FIII19_44-6"><sup><i><b>g</b></i></sup></a> <a href="#cite_ref-FIII19_44-7"><sup><i><b>h</b></i></sup></a> <a href="#cite_ref-FIII19_44-8"><sup><i><b>i</b></i></sup></a> <a href="#cite_ref-FIII19_44-9"><sup><i><b>j</b></i></sup></a> <a href="#cite_ref-FIII19_44-10"><sup><i><b>k</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFFeynmanLeightonSands1964" class="citation book cs1">Feynman, Richard; Leighton, Robert B.; Sands, Matthew (1964). 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Florida State University. 6 May 2020. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20220506074340/https://www.chem.fsu.edu/chemlab/chm1045/e_config.html">Archived</a> from the original on 6 May 2022<span class="reference-accessdate">. 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(1964). <a rel="nofollow" class="external text" href="https://www.pnas.org/content/51/4/664.full.pdf">"The Order of Electron Shells in Ionized Atoms"</a> <span class="cs1-format">(PDF)</span>. <i><a href="/wiki/Proceedings_of_the_National_Academy_of_Sciences_of_the_United_States_of_America" title="Proceedings of the National Academy of Sciences of the United States of America">Proc. Natl. Acad. Sci.</a></i> <b>51</b> (4): 664–671 (with correction on p 906). <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1964PNAS...51..664G">1964PNAS...51..664G</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1073%2Fpnas.51.4.664">10.1073/pnas.51.4.664</a></span>. <a href="/wiki/PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC300183">300183</a></span>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/16591167">16591167</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20171010113455/https://www.pnas.org/content/51/4/664.full.pdf">Archived</a> <span class="cs1-format">(PDF)</span> from the original on 10 October 2017<span class="reference-accessdate">. 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Retrieved <span class="nowrap">13 June</span> 2009</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=JINR+Communication&rft.atitle=Results+from+the+first+%3Cspan+class%3D%22chemf+nowrap%22%3E%3Cspan+class%3D%22nowrap%22%3E%3Cspan+style%3D%22display%3Ainline-block%3Bmargin-bottom%3A-0.3em%3Bvertical-align%3A0.5em%3Bline-height%3A1em%3Bfont-size%3A80%25%3Btext-align%3Aleft%22%3E%3Csup+style%3D%22font-size%3Ainherit%3Bline-height%3Ainherit%3Bvertical-align%3Abaseline%22%3E249%3C%2Fsup%3E%3Cbr+%2F%3E%3Csub+style%3D%22font-size%3Ainherit%3Bline-height%3Ainherit%3Bvertical-align%3Abaseline%22%3E%3C%2Fsub%3E%3C%2Fspan%3E%3C%2Fspan%3ECf%3C%2Fspan%3E%2B%3Cspan+class%3D%22chemf+nowrap%22%3E%3Cspan+class%3D%22nowrap%22%3E%3Cspan+style%3D%22display%3Ainline-block%3Bmargin-bottom%3A-0.3em%3Bvertical-align%3A0.5em%3Bline-height%3A1em%3Bfont-size%3A80%25%3Btext-align%3Aleft%22%3E%3Csup+style%3D%22font-size%3Ainherit%3Bline-height%3Ainherit%3Bvertical-align%3Abaseline%22%3E48%3C%2Fsup%3E%3Cbr+%2F%3E%3Csub+style%3D%22font-size%3Ainherit%3Bline-height%3Ainherit%3Bvertical-align%3Abaseline%22%3E%3C%2Fsub%3E%3C%2Fspan%3E%3C%2Fspan%3ECa%3C%2Fspan%3E+experiment&rft.date=2002&rft.au=Oganessian%2C+Yu.+T.&rft_id=https%3A%2F%2Fwww.jinr.ru%2Fpublish%2FPreprints%2F2002%2F287%28D7-2002-287%29e.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-IUPAC-20161130-88"><span class="mw-cite-backlink">^ <a href="#cite_ref-IUPAC-20161130_88-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-IUPAC-20161130_88-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation news cs1"><a rel="nofollow" class="external text" href="https://iupac.org/iupac-announces-the-names-of-the-elements-113-115-117-and-118/">"IUPAC Announces the Names of the Elements 113, 115, 117, and 118"</a>. <i><a href="/wiki/IUPAC" class="mw-redirect" title="IUPAC">IUPAC</a></i>. 30 November 2016. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20161130111959/https://iupac.org/iupac-announces-the-names-of-the-elements-113-115-117-and-118/">Archived</a> from the original on 30 November 2016<span class="reference-accessdate">. Retrieved <span class="nowrap">1 December</span> 2016</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=IUPAC&rft.atitle=IUPAC+Announces+the+Names+of+the+Elements+113%2C+115%2C+117%2C+and+118&rft.date=2016-11-30&rft_id=https%3A%2F%2Fiupac.org%2Fiupac-announces-the-names-of-the-elements-113-115-117-and-118%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-89"><span class="mw-cite-backlink"><b><a href="#cite_ref-89">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFNational_Institute_of_Standards_and_Technology_(NIST)2019" class="citation journal cs1"><a href="/wiki/National_Institute_of_Standards_and_Technology" title="National Institute of Standards and Technology">National Institute of Standards and Technology</a> (NIST) (August 2019). <a rel="nofollow" class="external text" href="https://www.nist.gov/pml/periodic-table-elements">"Periodic Table of the Elements"</a>. <i>NIST</i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210208182536/https://www.nist.gov/pml/periodic-table-elements">Archived</a> from the original on 8 February 2021<span class="reference-accessdate">. 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Berlin: Springer-Verlag: 89–144. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1007%2FBFb0116496">10.1007/BFb0116496</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-3-540-07109-9" title="Special:BookSources/978-3-540-07109-9"><bdi>978-3-540-07109-9</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Structure+and+Bonding&rft.atitle=Superheavy+elements+a+prediction+of+their+chemical+and+physical+properties&rft.volume=21&rft.pages=89-144&rft.date=1975&rft_id=info%3Adoi%2F10.1007%2FBFb0116496&rft.isbn=978-3-540-07109-9&rft.aulast=Fricke&rft.aufirst=B.&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-Lemonick-91"><span class="mw-cite-backlink">^ <a href="#cite_ref-Lemonick_91-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Lemonick_91-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Lemonick_91-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFLemonick2019" class="citation web cs1">Lemonick, Sam (2019). <a rel="nofollow" class="external text" href="https://cen.acs.org/physical-chemistry/periodic-table/periodic-table-icon-chemists-still/97/i1">"The periodic table is an icon. But chemists still can't agree on how to arrange it"</a>. <i>C&EN News</i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210128031450/https://cen.acs.org/physical-chemistry/periodic-table/periodic-table-icon-chemists-still/97/i1">Archived</a> from the original on 28 January 2021<span class="reference-accessdate">. Retrieved <span class="nowrap">16 December</span> 2020</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=C%26EN+News&rft.atitle=The+periodic+table+is+an+icon.+But+chemists+still+can%27t+agree+on+how+to+arrange+it&rft.date=2019&rft.aulast=Lemonick&rft.aufirst=Sam&rft_id=https%3A%2F%2Fcen.acs.org%2Fphysical-chemistry%2Fperiodic-table%2Fperiodic-table-icon-chemists-still%2F97%2Fi1&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-Gray12-92"><span class="mw-cite-backlink">^ <a href="#cite_ref-Gray12_92-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Gray12_92-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">Gray, p. 12</span> </li> <li id="cite_note-Vlasov-93"><span class="mw-cite-backlink">^ <a href="#cite_ref-Vlasov_93-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Vlasov_93-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Vlasov_93-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-Vlasov_93-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-Vlasov_93-4"><sup><i><b>e</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFVlasovTrifonov1970" class="citation book cs1">Vlasov, L.; Trifonov, D. (1970). <i>107 Stories About Chemistry</i>. Translated by Sobolev, D. Mir Publishers. pp. 23–27. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-8285-5067-3" title="Special:BookSources/978-0-8285-5067-3"><bdi>978-0-8285-5067-3</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=107+Stories+About+Chemistry&rft.pages=23-27&rft.pub=Mir+Publishers&rft.date=1970&rft.isbn=978-0-8285-5067-3&rft.aulast=Vlasov&rft.aufirst=L.&rft.au=Trifonov%2C+D.&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-raynercanham-94"><span class="mw-cite-backlink">^ <a href="#cite_ref-raynercanham_94-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-raynercanham_94-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-raynercanham_94-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-raynercanham_94-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-raynercanham_94-4"><sup><i><b>e</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFRayner-Canham2020" class="citation book cs1">Rayner-Canham, Geoffrey (2020). <i>The Periodic Table: Past, Present, Future</i>. World Scientific. pp. 53–70, 85–102. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-981-12-1850-7" title="Special:BookSources/978-981-12-1850-7"><bdi>978-981-12-1850-7</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Periodic+Table%3A+Past%2C+Present%2C+Future&rft.pages=53-70%2C+85-102&rft.pub=World+Scientific&rft.date=2020&rft.isbn=978-981-12-1850-7&rft.aulast=Rayner-Canham&rft.aufirst=Geoffrey&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-95"><span class="mw-cite-backlink"><b><a href="#cite_ref-95">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFClaydenGreevesWarrenWothers2001" class="citation book cs1"><a href="/wiki/Jonathan_Clayden" title="Jonathan Clayden">Clayden, Jonathan</a>; Greeves, Nick; <a href="/wiki/Stuart_Warren" title="Stuart Warren">Warren, Stuart</a>; <a href="/wiki/Peter_Wothers" title="Peter Wothers">Wothers, Peter</a> (2001). <i>Organic Chemistry</i> (1st ed.). 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"The chemical and radioactive properties of the heavy elements". <i>Chemical & Engineering News</i>. <b>23</b> (23): 2190–93. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1021%2Fcen-v023n023.p2190">10.1021/cen-v023n023.p2190</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Chemical+%26+Engineering+News&rft.atitle=The+chemical+and+radioactive+properties+of+the+heavy+elements&rft.volume=23&rft.issue=23&rft.pages=2190-93&rft.date=1945&rft_id=info%3Adoi%2F10.1021%2Fcen-v023n023.p2190&rft.aulast=Seaborg&rft.aufirst=G.&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-Kaesz-97"><span class="mw-cite-backlink">^ <a href="#cite_ref-Kaesz_97-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Kaesz_97-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFKaeszAtkins2009" class="citation journal cs1">Kaesz, Herb; Atkins, Peter (2009). <a rel="nofollow" class="external text" href="https://doi.org/10.1515%2Fci.2003.25.6.14">"A Central Position for Hydrogen in the Periodic Table"</a>. <i>Chemistry International</i>. <b>25</b> (6): 14. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1515%2Fci.2003.25.6.14">10.1515/ci.2003.25.6.14</a></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Chemistry+International&rft.atitle=A+Central+Position+for+Hydrogen+in+the+Periodic+Table&rft.volume=25&rft.issue=6&rft.pages=14&rft.date=2009&rft_id=info%3Adoi%2F10.1515%2Fci.2003.25.6.14&rft.aulast=Kaesz&rft.aufirst=Herb&rft.au=Atkins%2C+Peter&rft_id=https%3A%2F%2Fdoi.org%2F10.1515%252Fci.2003.25.6.14&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-GE-98"><span class="mw-cite-backlink">^ <a href="#cite_ref-GE_98-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-GE_98-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">Greenwood & Earnshaw, throughout the book</span> </li> <li id="cite_note-99"><span class="mw-cite-backlink"><b><a href="#cite_ref-99">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFScerri2004" class="citation journal cs1">Scerri, Eric (2004). <a rel="nofollow" class="external text" href="http://publications.iupac.org/ci/2004/2603/ud2_scerri.html">"The Placement of Hydrogen in the Periodic Table"</a>. <i>Chemistry International</i>. <b>26</b> (3): 21–22. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1515%2Fci.2004.26.3.21">10.1515/ci.2004.26.3.21</a></span><span class="reference-accessdate">. Retrieved <span class="nowrap">1 January</span> 2023</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Chemistry+International&rft.atitle=The+Placement+of+Hydrogen+in+the+Periodic+Table&rft.volume=26&rft.issue=3&rft.pages=21-22&rft.date=2004&rft_id=info%3Adoi%2F10.1515%2Fci.2004.26.3.21&rft.aulast=Scerri&rft.aufirst=Eric&rft_id=http%3A%2F%2Fpublications.iupac.org%2Fci%2F2004%2F2603%2Fud2_scerri.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-shattered-100"><span class="mw-cite-backlink">^ <a href="#cite_ref-shattered_100-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-shattered_100-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFThyssenCeulemans2017" class="citation book cs1">Thyssen, Pieter; Ceulemans, Arnout (2017). <i>Shattered Symmetry: Group Theory from the Eightfold Way to the Periodic Table</i>. Oxford University Press. pp. 336, 360–381. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-19-061139-2" title="Special:BookSources/978-0-19-061139-2"><bdi>978-0-19-061139-2</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Shattered+Symmetry%3A+Group+Theory+from+the+Eightfold+Way+to+the+Periodic+Table&rft.pages=336%2C+360-381&rft.pub=Oxford+University+Press&rft.date=2017&rft.isbn=978-0-19-061139-2&rft.aulast=Thyssen&rft.aufirst=Pieter&rft.au=Ceulemans%2C+Arnout&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-Kurushkin-101"><span class="mw-cite-backlink"><b><a href="#cite_ref-Kurushkin_101-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFKurushkin2020" class="citation journal cs1">Kurushkin, Mikhail (2020). <a rel="nofollow" class="external text" href="https://www.researchgate.net/publication/342152661">"Helium's placement in the Periodic Table from a crystal structure viewpoint"</a>. <i>IUCrJ</i>. <b>7</b> (4): 577–578. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2020IUCrJ...7..577K">2020IUCrJ...7..577K</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1107%2FS2052252520007769">10.1107/S2052252520007769</a></span>. <a href="/wiki/PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7340260">7340260</a></span>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/32695406">32695406</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20211019202250/https://www.researchgate.net/publication/342152661_Helium's_placement_in_the_Periodic_Table_from_a_crystal_structure_viewpoint">Archived</a> from the original on 19 October 2021<span class="reference-accessdate">. Retrieved <span class="nowrap">19 June</span> 2020</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=IUCrJ&rft.atitle=Helium%27s+placement+in+the+Periodic+Table+from+a+crystal+structure+viewpoint&rft.volume=7&rft.issue=4&rft.pages=577-578&rft.date=2020&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC7340260%23id-name%3DPMC&rft_id=info%3Apmid%2F32695406&rft_id=info%3Adoi%2F10.1107%2FS2052252520007769&rft_id=info%3Abibcode%2F2020IUCrJ...7..577K&rft.aulast=Kurushkin&rft.aufirst=Mikhail&rft_id=https%3A%2F%2Fwww.researchgate.net%2Fpublication%2F342152661&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-PTSS-102"><span class="mw-cite-backlink">^ <a href="#cite_ref-PTSS_102-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-PTSS_102-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-PTSS_102-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-PTSS_102-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text">Scerri, pp. 392−401</span> </li> <li id="cite_note-grochala-103"><span class="mw-cite-backlink">^ <a href="#cite_ref-grochala_103-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-grochala_103-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFGrochala2017" class="citation journal cs1">Grochala, Wojciech (1 November 2017). <a rel="nofollow" class="external text" href="https://doi.org/10.1007%2Fs10698-017-9302-7">"On the position of helium and neon in the Periodic Table of Elements"</a>. <i>Foundations of Chemistry</i>. <b>20</b> (2018): 191–207. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1007%2Fs10698-017-9302-7">10.1007/s10698-017-9302-7</a></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Foundations+of+Chemistry&rft.atitle=On+the+position+of+helium+and+neon+in+the+Periodic+Table+of+Elements&rft.volume=20&rft.issue=2018&rft.pages=191-207&rft.date=2017-11-01&rft_id=info%3Adoi%2F10.1007%2Fs10698-017-9302-7&rft.aulast=Grochala&rft.aufirst=Wojciech&rft_id=https%3A%2F%2Fdoi.org%2F10.1007%252Fs10698-017-9302-7&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-104"><span class="mw-cite-backlink"><b><a href="#cite_ref-104">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBent_Weberg2019" class="citation journal cs1">Bent Weberg, Libby (18 January 2019). <a rel="nofollow" class="external text" href="https://cen.acs.org/articles/97/i3/Reactions.html">"<span class="cs1-kern-left"></span>"The" periodic table"</a>. <i>Chemical & Engineering News</i>. <b>97</b> (3). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20200201200009/https://cen.acs.org/articles/97/i3/Reactions.html">Archived</a> from the original on 1 February 2020<span class="reference-accessdate">. Retrieved <span class="nowrap">27 March</span> 2020</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Chemical+%26+Engineering+News&rft.atitle=%22The%22+periodic+table&rft.volume=97&rft.issue=3&rft.date=2019-01-18&rft.aulast=Bent+Weberg&rft.aufirst=Libby&rft_id=https%3A%2F%2Fcen.acs.org%2Farticles%2F97%2Fi3%2FReactions.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-105"><span class="mw-cite-backlink"><b><a href="#cite_ref-105">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFGrandinetti2013" class="citation journal cs1">Grandinetti, Felice (23 April 2013). <a rel="nofollow" class="external text" href="https://doi.org/10.1038%2Fnchem.1631">"Neon behind the signs"</a>. <i>Nature Chemistry</i>. <b>5</b> (2013): 438. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2013NatCh...5..438G">2013NatCh...5..438G</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1038%2Fnchem.1631">10.1038/nchem.1631</a></span>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/23609097">23609097</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Nature+Chemistry&rft.atitle=Neon+behind+the+signs&rft.volume=5&rft.issue=2013&rft.pages=438&rft.date=2013-04-23&rft_id=info%3Apmid%2F23609097&rft_id=info%3Adoi%2F10.1038%2Fnchem.1631&rft_id=info%3Abibcode%2F2013NatCh...5..438G&rft.aulast=Grandinetti&rft.aufirst=Felice&rft_id=https%3A%2F%2Fdoi.org%2F10.1038%252Fnchem.1631&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-SB23-106"><span class="mw-cite-backlink">^ <a href="#cite_ref-SB23_106-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-SB23_106-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-SB23_106-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-SB23_106-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-SB23_106-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-SB23_106-5"><sup><i><b>f</b></i></sup></a></span> <span class="reference-text">Siekierski and Burgess, pp. 23–26</span> </li> <li id="cite_note-107"><span class="mw-cite-backlink"><b><a href="#cite_ref-107">^</a></b></span> <span class="reference-text">Siekierski and Burgess, p. 128</span> </li> <li id="cite_note-108"><span class="mw-cite-backlink"><b><a href="#cite_ref-108">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFLewars2008" class="citation book cs1">Lewars, Errol G. (5 December 2008). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=IoFzgBSSCwEC"><i>Modeling Marvels: Computational Anticipation of Novel Molecules</i></a>. Springer Science & Business Media. pp. 69–71. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-4020-6973-4" title="Special:BookSources/978-1-4020-6973-4"><bdi>978-1-4020-6973-4</bdi></a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20160519021952/https://books.google.com/books?id=IoFzgBSSCwEC">Archived</a> from the original on 19 May 2016.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Modeling+Marvels%3A+Computational+Anticipation+of+Novel+Molecules&rft.pages=69-71&rft.pub=Springer+Science+%26+Business+Media&rft.date=2008-12-05&rft.isbn=978-1-4020-6973-4&rft.aulast=Lewars&rft.aufirst=Errol+G.&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DIoFzgBSSCwEC&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-wulfsberg53-109"><span class="mw-cite-backlink">^ <a href="#cite_ref-wulfsberg53_109-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-wulfsberg53_109-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">Wulfsberg, p. 53: "As pointed out by W. B. Jensen, the metallurgical resemblance [to yttrium] is much stronger for lutetium than for lanthanum, so we have adopted the metallurgist's convention of listing Lu (and by extension Lr) below Sc and Y. An important additional advantage of this is that the periodic table becomes more symmetrical, and it becomes easier to predict electron configurations. E. R. Scerri points out that recent determinations of the electron configurations of most of the <i>f</i>-block elements now are more compatible with this placement of Lu and Lr."</span> </li> <li id="cite_note-Kondo-110"><span class="mw-cite-backlink">^ <a href="#cite_ref-Kondo_110-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Kondo_110-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFKondō1963" class="citation journal cs1">Kondō, Jun (January 1963). <a rel="nofollow" class="external text" href="https://doi.org/10.1143%2FPTP.29.1">"Superconductivity in Transition Metals"</a>. <i>Progress of Theoretical Physics</i>. <b>29</b> (1): 1–9. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1963PThPh..29....1K">1963PThPh..29....1K</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1143%2FPTP.29.1">10.1143/PTP.29.1</a></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Progress+of+Theoretical+Physics&rft.atitle=Superconductivity+in+Transition+Metals&rft.volume=29&rft.issue=1&rft.pages=1-9&rft.date=1963-01&rft_id=info%3Adoi%2F10.1143%2FPTP.29.1&rft_id=info%3Abibcode%2F1963PThPh..29....1K&rft.aulast=Kond%C5%8D&rft.aufirst=Jun&rft_id=https%3A%2F%2Fdoi.org%2F10.1143%252FPTP.29.1&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-JWP-111"><span class="mw-cite-backlink"><b><a href="#cite_ref-JWP_111-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBarber,_Robert_C.Karol,_Paul_JNakahara,_HiromichiVardaci,_Emanuele2011" class="citation journal cs1">Barber, Robert C.; Karol, Paul J; Nakahara, Hiromichi; Vardaci, Emanuele; Vogt, Erich W. (2011). <a rel="nofollow" class="external text" href="https://doi.org/10.1351%2FPAC-REP-10-05-01">"Discovery of the elements with atomic numbers greater than or equal to 113 (IUPAC Technical Report)"</a>. <i>Pure Appl. Chem</i>. <b>83</b> (7): 1485. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1351%2FPAC-REP-10-05-01">10.1351/PAC-REP-10-05-01</a></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Pure+Appl.+Chem.&rft.atitle=Discovery+of+the+elements+with+atomic+numbers+greater+than+or+equal+to+113+%28IUPAC+Technical+Report%29&rft.volume=83&rft.issue=7&rft.pages=1485&rft.date=2011&rft_id=info%3Adoi%2F10.1351%2FPAC-REP-10-05-01&rft.au=Barber%2C+Robert+C.&rft.au=Karol%2C+Paul+J&rft.au=Nakahara%2C+Hiromichi&rft.au=Vardaci%2C+Emanuele&rft.au=Vogt%2C+Erich+W.&rft_id=https%3A%2F%2Fdoi.org%2F10.1351%252FPAC-REP-10-05-01&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-Karol-112"><span class="mw-cite-backlink"><b><a href="#cite_ref-Karol_112-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFKarolBarberSherrillVardaci2015" class="citation journal cs1">Karol, Paul J.; Barber, Robert C.; Sherrill, Bradley M.; Vardaci, Emanuele; Yamazaki, Toshimitsu (22 December 2015). <a rel="nofollow" class="external text" href="https://doi.org/10.1515%2Fpac-2015-0502">"Discovery of the elements with atomic numbers Z = 113, 115 and 117 (IUPAC Technical Report)"</a>. <i>Pure Appl. 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Retrieved <span class="nowrap">20 October</span> 2023</span> – via OSTI. <q>Superheavy elements (<i>Z</i> > 102) are teetering at the limits of mass and charge.</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=A+New+Era+of+Discovery%3A+the+2023+Long+Range+Plan+for+Nuclear+Science&rft.pub=U.S.+Department+of+Energy&rft.date=2023-10&rft_id=https%3A%2F%2Fscience.osti.gov%2F-%2Fmedia%2Fnp%2Fnsac%2Fpdf%2F202310%2FOctober-4-LRP-Report.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-210"><span class="mw-cite-backlink"><b><a href="#cite_ref-210">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFKragh2017" class="citation arxiv cs1">Kragh, Helge (2017). 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The Chemical Society of Japan. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210516062728/https://www.chemistry.or.jp/news/information/1-2.html">Archived</a> from the original on 16 May 2021<span class="reference-accessdate">. Retrieved <span class="nowrap">3 April</span> 2021</span>. <q>「12.アルカリ土類金属」の範囲についても,△を含めれば,すべての教科書で提案が考慮されている。歴史的には第4 周期のカルシウム以下を指していた用語だったが,「周期表の2 族に対応する用語とする」というIUPAC の勧告1)に従うのは現在では自然な流れだろう。</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.chemistry.or.jp&rft.atitle=%E3%80%90%E3%81%8A%E7%9F%A5%E3%82%89%E3%81%9B%E3%80%91%E9%AB%98%E7%AD%89%E5%AD%A6%E6%A0%A1%E5%8C%96%E5%AD%A6%E3%81%A7%E7%94%A8%E3%81%84%E3%82%8B%E7%94%A8%E8%AA%9E%E3%81%AB%E9%96%A2%E3%81%99%E3%82%8B%E6%8F%90%E6%A1%88%EF%BC%881%EF%BC%89%E3%81%B8%E3%81%AE%E5%8F%8D%E5%BF%9C&rft.date=2018-01-25&rft.au=The+Chemical+Society+of+Japan&rft_id=https%3A%2F%2Fwww.chemistry.or.jp%2Fnews%2Finformation%2F1-2.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-217"><span class="mw-cite-backlink"><b><a href="#cite_ref-217">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWurzer1817" class="citation journal cs1 cs1-prop-foreign-lang-source">Wurzer, Ferdinand (1817). <a rel="nofollow" class="external text" href="https://babel.hathitrust.org/cgi/pt?id=chi.096071138;view=1up;seq=351">"Auszug eines Briefes vom Hofrath Wurzer, Prof. der Chemie zu Marburg"</a> [Excerpt of a letter from Court Advisor Wurzer, Professor of Chemistry at Marburg]. <i>Annalen der Physik</i> (in German). <b>56</b> (7): 331–334. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1817AnP....56..331.">1817AnP....56..331.</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1002%2Fandp.18170560709">10.1002/andp.18170560709</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20211008024621/https://babel.hathitrust.org/cgi/pt?id=chi.096071138;view=1up;seq=351">Archived</a> from the original on 8 October 2021<span class="reference-accessdate">. Retrieved <span class="nowrap">15 August</span> 2021</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Annalen+der+Physik&rft.atitle=Auszug+eines+Briefes+vom+Hofrath+Wurzer%2C+Prof.+der+Chemie+zu+Marburg&rft.volume=56&rft.issue=7&rft.pages=331-334&rft.date=1817&rft_id=info%3Adoi%2F10.1002%2Fandp.18170560709&rft_id=info%3Abibcode%2F1817AnP....56..331.&rft.aulast=Wurzer&rft.aufirst=Ferdinand&rft_id=https%3A%2F%2Fbabel.hathitrust.org%2Fcgi%2Fpt%3Fid%3Dchi.096071138%3Bview%3D1up%3Bseq%3D351&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span> Here, Döbereiner found that strontium's properties were intermediate to those of calcium and barium.</span> </li> <li id="cite_note-218"><span class="mw-cite-backlink"><b><a href="#cite_ref-218">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFDöbereiner1829" class="citation journal cs1 cs1-prop-foreign-lang-source">Döbereiner, J. W. (1829). <a rel="nofollow" class="external text" href="https://babel.hathitrust.org/cgi/pt?id=mdp.39015065410634;view=1up;seq=315">"Versuch zu einer Gruppirung der elementaren Stoffe nach ihrer Analogie"</a> [An attempt to group elementary substances according to their analogies]. <i>Annalen der Physik und Chemie</i>. 2nd series (in German). <b>15</b> (2): 301–307. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1829AnP....91..301D">1829AnP....91..301D</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1002%2Fandp.18290910217">10.1002/andp.18290910217</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20211008024625/https://babel.hathitrust.org/cgi/pt?id=mdp.39015065410634;view=1up;seq=315">Archived</a> from the original on 8 October 2021<span class="reference-accessdate">. Retrieved <span class="nowrap">15 August</span> 2021</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Annalen+der+Physik+und+Chemie&rft.atitle=Versuch+zu+einer+Gruppirung+der+elementaren+Stoffe+nach+ihrer+Analogie&rft.volume=15&rft.issue=2&rft.pages=301-307&rft.date=1829&rft_id=info%3Adoi%2F10.1002%2Fandp.18290910217&rft_id=info%3Abibcode%2F1829AnP....91..301D&rft.aulast=D%C3%B6bereiner&rft.aufirst=J.+W.&rft_id=https%3A%2F%2Fbabel.hathitrust.org%2Fcgi%2Fpt%3Fid%3Dmdp.39015065410634%3Bview%3D1up%3Bseq%3D315&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span> For an English translation of this article, see: <a rel="nofollow" class="external text" href="https://web.lemoyne.edu/~giunta/dobereiner.html">Johann Wolfgang Döbereiner: "An Attempt to Group Elementary Substances according to Their Analogies" (Lemoyne College (Syracuse, New York, USA))</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20190309161429/https://web.lemoyne.edu/~GIUNTA/dobereiner.html">Archived</a> 9 March 2019 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a></span> </li> <li id="cite_note-219"><span class="mw-cite-backlink"><b><a href="#cite_ref-219">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFHorvitz2002" class="citation book cs1">Horvitz, L. (2002). <i>Eureka!: Scientific Breakthroughs That Changed The World</i>. New York: John Wiley. p. 43. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2001esbt.book.....H">2001esbt.book.....H</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-471-23341-1" title="Special:BookSources/978-0-471-23341-1"><bdi>978-0-471-23341-1</bdi></a>. <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/50766822">50766822</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Eureka%21%3A+Scientific+Breakthroughs+That+Changed+The+World&rft.place=New+York&rft.pages=43&rft.pub=John+Wiley&rft.date=2002&rft_id=info%3Aoclcnum%2F50766822&rft_id=info%3Abibcode%2F2001esbt.book.....H&rft.isbn=978-0-471-23341-1&rft.aulast=Horvitz&rft.aufirst=L.&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-220"><span class="mw-cite-backlink"><b><a href="#cite_ref-220">^</a></b></span> <span class="reference-text">Scerri, p. 47</span> </li> <li id="cite_note-221"><span class="mw-cite-backlink"><b><a href="#cite_ref-221">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBall2002" class="citation book cs1"><a href="/wiki/Philip_Ball" title="Philip Ball">Ball, P.</a> (2002). <i>The Ingredients: A Guided Tour of the Elements</i>. Oxford: Oxford University Press. p. 100. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-19-284100-1" title="Special:BookSources/978-0-19-284100-1"><bdi>978-0-19-284100-1</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Ingredients%3A+A+Guided+Tour+of+the+Elements&rft.place=Oxford&rft.pages=100&rft.pub=Oxford+University+Press&rft.date=2002&rft.isbn=978-0-19-284100-1&rft.aulast=Ball&rft.aufirst=P.&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-EB1911-222"><span class="mw-cite-backlink">^ <a href="#cite_ref-EB1911_222-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-EB1911_222-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFChisholm1911" class="citation encyclopaedia cs1"><a href="/wiki/Hugh_Chisholm" title="Hugh Chisholm">Chisholm, Hugh</a>, ed. (1911). <span class="cs1-ws-icon" title="s:1911 Encyclopædia Britannica/Newlands, John Alexander Reina"><a class="external text" href="https://en.wikisource.org/wiki/1911_Encyclop%C3%A6dia_Britannica/Newlands,_John_Alexander_Reina">"Newlands, John Alexander Reina" </a></span>. <i><a href="/wiki/Encyclop%C3%A6dia_Britannica_Eleventh_Edition" title="Encyclopædia Britannica Eleventh Edition">Encyclopædia Britannica</a></i>. Vol. 19 (11th ed.). Cambridge University Press. p. 515.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Newlands%2C+John+Alexander+Reina&rft.btitle=Encyclop%C3%A6dia+Britannica&rft.pages=515&rft.edition=11th&rft.pub=Cambridge+University+Press&rft.date=1911&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-Meyer_table-223"><span class="mw-cite-backlink"><b><a href="#cite_ref-Meyer_table_223-0">^</a></b></span> <span class="reference-text">Meyer, Julius Lothar; Die modernen Theorien der Chemie (1864); <a rel="nofollow" class="external text" href="https://reader.digitale-sammlungen.de/de/fs1/object/goToPage/bsb10073411.html?pageNo=147">table on page 137</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20190102050414/https://reader.digitale-sammlungen.de/de/fs1/object/goToPage/bsb10073411.html?pageNo=147">Archived</a> 2 January 2019 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a></span> </li> <li id="cite_note-224"><span class="mw-cite-backlink"><b><a href="#cite_ref-224">^</a></b></span> <span class="reference-text">Scerri, pp. 106–108</span> </li> <li id="cite_note-225"><span class="mw-cite-backlink"><b><a href="#cite_ref-225">^</a></b></span> <span class="reference-text">Scerri, p. 113</span> </li> <li id="cite_note-Scerri117-226"><span class="mw-cite-backlink">^ <a href="#cite_ref-Scerri117_226-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Scerri117_226-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">Scerri, pp. 117–123</span> </li> <li id="cite_note-mendeleev1871-227"><span class="mw-cite-backlink"><b><a href="#cite_ref-mendeleev1871_227-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMendeleev1871" class="citation journal cs1 cs1-prop-foreign-lang-source">Mendeleev, D. (1871). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20170813142644/https://www.knigafund.ru/books/56718/read#page31">"The natural system of elements and its application to the indication of the properties of undiscovered elements"</a>. <i>Journal of the Russian Chemical Society</i> (in Russian). <b>3</b>: 25–56. Archived from <a rel="nofollow" class="external text" href="https://www.knigafund.ru/books/56718/read#page31">the original</a> on 13 August 2017<span class="reference-accessdate">. Retrieved <span class="nowrap">23 August</span> 2017</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+of+the+Russian+Chemical+Society&rft.atitle=The+natural+system+of+elements+and+its+application+to+the+indication+of+the+properties+of+undiscovered+elements&rft.volume=3&rft.pages=25-56&rft.date=1871&rft.aulast=Mendeleev&rft.aufirst=D.&rft_id=https%3A%2F%2Fwww.knigafund.ru%2Fbooks%2F56718%2Fread%23page31&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-228"><span class="mw-cite-backlink"><b><a href="#cite_ref-228">^</a></b></span> <span class="reference-text">Scerri, p. 149</span> </li> <li id="cite_note-229"><span class="mw-cite-backlink"><b><a href="#cite_ref-229">^</a></b></span> <span class="reference-text">Scerri, p. 151–2</span> </li> <li id="cite_note-230"><span class="mw-cite-backlink"><b><a href="#cite_ref-230">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFRouvray" class="citation web cs1">Rouvray, R. <a rel="nofollow" class="external text" href="https://www.newscientist.com/people/dmitri-mendeleev/">"Dmitri Mendeleev"</a>. <i>New Scientist</i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210815074119/https://www.newscientist.com/people/dmitri-mendeleev/">Archived</a> from the original on 15 August 2021<span class="reference-accessdate">. Retrieved <span class="nowrap">19 April</span> 2020</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=New+Scientist&rft.atitle=Dmitri+Mendeleev&rft.aulast=Rouvray&rft.aufirst=R.&rft_id=https%3A%2F%2Fwww.newscientist.com%2Fpeople%2Fdmitri-mendeleev%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-Scerri164-231"><span class="mw-cite-backlink"><b><a href="#cite_ref-Scerri164_231-0">^</a></b></span> <span class="reference-text">Scerri, pp. 164–169</span> </li> <li id="cite_note-moseley2010-232"><span class="mw-cite-backlink">^ <a href="#cite_ref-moseley2010_232-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-moseley2010_232-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-moseley2010_232-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMarshallMarshall2010" class="citation magazine cs1">Marshall, J.L.; Marshall, V.R. (2010). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20190716215907/https://pdfs.semanticscholar.org/afe4/8822cd0871e65dc5401166e7df68dc0ecb7f.pdf">"Rediscovery of the Elements: Moseley and Atomic Numbers"</a> <span class="cs1-format">(PDF)</span>. <i>The Hexagon</i>. Vol. 101, no. 3. <a href="/wiki/Alpha_Chi_Sigma" title="Alpha Chi Sigma">Alpha Chi Sigma</a>. pp. 42–47. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:94398490">94398490</a>. Archived from <a rel="nofollow" class="external text" href="https://pdfs.semanticscholar.org/afe4/8822cd0871e65dc5401166e7df68dc0ecb7f.pdf">the original</a> <span class="cs1-format">(PDF)</span> on 16 July 2019<span class="reference-accessdate">. Retrieved <span class="nowrap">15 August</span> 2021</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+Hexagon&rft.atitle=Rediscovery+of+the+Elements%3A+Moseley+and+Atomic+Numbers&rft.volume=101&rft.issue=3&rft.pages=42-47&rft.date=2010&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A94398490%23id-name%3DS2CID&rft.aulast=Marshall&rft.aufirst=J.L.&rft.au=Marshall%2C+V.R.&rft_id=https%3A%2F%2Fpdfs.semanticscholar.org%2Fafe4%2F8822cd0871e65dc5401166e7df68dc0ecb7f.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-233"><span class="mw-cite-backlink"><b><a href="#cite_ref-233">^</a></b></span> <span class="reference-text">A. van den Broek, <i><a href="/wiki/Physikalische_Zeitschrift" title="Physikalische Zeitschrift">Physikalische Zeitschrift</a></i>, 14, (1913), 32–41</span> </li> <li id="cite_note-234"><span class="mw-cite-backlink"><b><a href="#cite_ref-234">^</a></b></span> <span class="reference-text">Scerri, p. 185</span> </li> <li id="cite_note-235"><span class="mw-cite-backlink"><b><a href="#cite_ref-235">^</a></b></span> <span class="reference-text">A. van den Broek, Die Radioelemente, das periodische System und die Konstitution der Atom, Physik. Zeitsch., 14, 32, (1913).</span> </li> <li id="cite_note-236"><span class="mw-cite-backlink"><b><a href="#cite_ref-236">^</a></b></span> <span class="reference-text">E. Rutherford, Phil. Mag., 27, 488–499 (Mar. 1914). "This has led to an interesting suggestion by van Broek that the number of units of charge on the nucleus, and consequently the number of external electrons, may be equal to the number of the elements when arranged in order of increasing atomic weight. On this view, the nucleus charges of hydrogen, helium, and carbon are 1, 2, 6 respectively, and so on for the other elements, provided there is no gap due to a missing element. This view has been taken by Bohr in his theory of the constitution of simple atoms and molecules."</span> </li> <li id="cite_note-237"><span class="mw-cite-backlink"><b><a href="#cite_ref-237">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFAtkins,_P._W.1995" class="citation book cs1"><a href="/wiki/P._W._Atkins" class="mw-redirect" title="P. W. Atkins">Atkins, P. W.</a> (1995). <a rel="nofollow" class="external text" href="https://archive.org/details/periodickingdomj00atki/page/87"><i>The Periodic Kingdom</i></a>. HarperCollins Publishers, Inc. p. <a rel="nofollow" class="external text" href="https://archive.org/details/periodickingdomj00atki/page/87">87</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-465-07265-1" title="Special:BookSources/978-0-465-07265-1"><bdi>978-0-465-07265-1</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Periodic+Kingdom&rft.pages=87&rft.pub=HarperCollins+Publishers%2C+Inc.&rft.date=1995&rft.isbn=978-0-465-07265-1&rft.au=Atkins%2C+P.+W.&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fperiodickingdomj00atki%2Fpage%2F87&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-238"><span class="mw-cite-backlink"><b><a href="#cite_ref-238">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFEgdellBruton2020" class="citation journal cs1">Egdell, Russell G.; Bruton, Elizabeth (2020). <a rel="nofollow" class="external text" href="https://doi.org/10.1002%2Fchem.202004775">"Henry Moseley, X-ray spectroscopy and the periodic table"</a>. <i>Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences</i>. <b>378</b> (2180). <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1002%2Fchem.202004775">10.1002/chem.202004775</a></span>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/32811359">32811359</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Philosophical+Transactions+of+the+Royal+Society+A%3A+Mathematical%2C+Physical+and+Engineering+Sciences&rft.atitle=Henry+Moseley%2C+X-ray+spectroscopy+and+the+periodic+table&rft.volume=378&rft.issue=2180&rft.date=2020&rft_id=info%3Adoi%2F10.1002%2Fchem.202004775&rft_id=info%3Apmid%2F32811359&rft.aulast=Egdell&rft.aufirst=Russell+G.&rft.au=Bruton%2C+Elizabeth&rft_id=https%3A%2F%2Fdoi.org%2F10.1002%252Fchem.202004775&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-nipponium2022-239"><span class="mw-cite-backlink"><b><a href="#cite_ref-nipponium2022_239-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFHisamatsuEgashiraMaeno2022" class="citation journal cs1">Hisamatsu, Yoji; Egashira, Kazuhiro; Maeno, Yoshiteru (2022). <a rel="nofollow" class="external text" href="https://doi.org/10.1007%2Fs10698-021-09410-x">"Ogawa's nipponium and its re-assignment to rhenium"</a>. <i>Foundations of Chemistry</i>. <b>24</b>: 15–57. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1007%2Fs10698-021-09410-x">10.1007/s10698-021-09410-x</a></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Foundations+of+Chemistry&rft.atitle=Ogawa%27s+nipponium+and+its+re-assignment+to+rhenium&rft.volume=24&rft.pages=15-57&rft.date=2022&rft_id=info%3Adoi%2F10.1007%2Fs10698-021-09410-x&rft.aulast=Hisamatsu&rft.aufirst=Yoji&rft.au=Egashira%2C+Kazuhiro&rft.au=Maeno%2C+Yoshiteru&rft_id=https%3A%2F%2Fdoi.org%2F10.1007%252Fs10698-021-09410-x&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-7elements-240"><span class="mw-cite-backlink">^ <a href="#cite_ref-7elements_240-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-7elements_240-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-7elements_240-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFScerri2013" class="citation book cs1">Scerri, Eric (2013). <i>A Tale of Seven Elements</i>. Oxford University Press. pp. 47–53, 115. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-19-539131-2" title="Special:BookSources/978-0-19-539131-2"><bdi>978-0-19-539131-2</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=A+Tale+of+Seven+Elements&rft.pages=47-53%2C+115&rft.pub=Oxford+University+Press&rft.date=2013&rft.isbn=978-0-19-539131-2&rft.aulast=Scerri&rft.aufirst=Eric&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-241"><span class="mw-cite-backlink"><b><a href="#cite_ref-241">^</a></b></span> <span class="reference-text">See Bohr table from 1913 paper below.</span> </li> <li id="cite_note-242"><span class="mw-cite-backlink"><b><a href="#cite_ref-242">^</a></b></span> <span class="reference-text">Helge Kragh, Aarhus, Lars Vegard, Atomic Structure, and the Periodic System, Bull. Hist. Chem., VOLUME 37, Number 1 (2012), p.43.</span> </li> <li id="cite_note-Scerri208-243"><span class="mw-cite-backlink"><b><a href="#cite_ref-Scerri208_243-0">^</a></b></span> <span class="reference-text">Scerri, pp. 208–218</span> </li> <li id="cite_note-244"><span class="mw-cite-backlink"><b><a href="#cite_ref-244">^</a></b></span> <span class="reference-text">Niels Bohr, "On the Constitution of Atoms and Molecules, Part III, Systems containing several nuclei" Philosophical Magazine 26:857--875 (1913)</span> </li> <li id="cite_note-245"><span class="mw-cite-backlink"><b><a href="#cite_ref-245">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFKragh1979" class="citation journal cs1">Kragh, Helge (1 January 1979). <a rel="nofollow" class="external text" href="https://online.ucpress.edu/hsns/article/doi/10.2307/27757389/47571/Niels-Bohr-s-Second-Atomic-Theory">"Niels Bohr's Second Atomic Theory"</a>. <i>Historical Studies in the Physical Sciences</i>. <b>10</b>: 123–186. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.2307%2F27757389">10.2307/27757389</a>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0073-2672">0073-2672</a>. <a href="/wiki/JSTOR_(identifier)" class="mw-redirect" title="JSTOR (identifier)">JSTOR</a> <a rel="nofollow" class="external text" href="https://www.jstor.org/stable/27757389">27757389</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Historical+Studies+in+the+Physical+Sciences&rft.atitle=Niels+Bohr%27s+Second+Atomic+Theory&rft.volume=10&rft.pages=123-186&rft.date=1979-01-01&rft.issn=0073-2672&rft_id=https%3A%2F%2Fwww.jstor.org%2Fstable%2F27757389%23id-name%3DJSTOR&rft_id=info%3Adoi%2F10.2307%2F27757389&rft.aulast=Kragh&rft.aufirst=Helge&rft_id=https%3A%2F%2Fonline.ucpress.edu%2Fhsns%2Farticle%2Fdoi%2F10.2307%2F27757389%2F47571%2FNiels-Bohr-s-Second-Atomic-Theory&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-246"><span class="mw-cite-backlink"><b><a href="#cite_ref-246">^</a></b></span> <span class="reference-text">W. Kossel, "Über Molekülbildung als Folge des Atom- baues", Ann. Phys., 1916, 49, 229–362 (237).</span> </li> <li id="cite_note-247"><span class="mw-cite-backlink"><b><a href="#cite_ref-247">^</a></b></span> <span class="reference-text">Translated in Helge Kragh, Aarhus, Lars Vegard, Atomic Structure, and the Periodic System, Bull. Hist. Chem., VOLUME 37, Number 1 (2012), p.43.</span> </li> <li id="cite_note-248"><span class="mw-cite-backlink"><b><a href="#cite_ref-248">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFLangmuir1919" class="citation journal cs1"><a href="/wiki/Irving_Langmuir" title="Irving Langmuir">Langmuir, Irving</a> (June 1919). <a rel="nofollow" class="external text" href="https://pubs.acs.org/doi/abs/10.1021/ja02227a002">"The Arrangement of Electrons in Atoms and Molecules"</a>. <i><a href="/wiki/Journal_of_the_American_Chemical_Society" title="Journal of the American Chemical Society">Journal of the American Chemical Society</a></i>. <b>41</b> (6): 868–934. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1021%2Fja02227a002">10.1021/ja02227a002</a>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0002-7863">0002-7863</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210126003324/https://zenodo.org/record/1429026">Archived</a> from the original on 26 January 2021<span class="reference-accessdate">. Retrieved <span class="nowrap">22 October</span> 2021</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+of+the+American+Chemical+Society&rft.atitle=The+Arrangement+of+Electrons+in+Atoms+and+Molecules&rft.volume=41&rft.issue=6&rft.pages=868-934&rft.date=1919-06&rft_id=info%3Adoi%2F10.1021%2Fja02227a002&rft.issn=0002-7863&rft.aulast=Langmuir&rft.aufirst=Irving&rft_id=https%3A%2F%2Fpubs.acs.org%2Fdoi%2Fabs%2F10.1021%2Fja02227a002&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-Bury-249"><span class="mw-cite-backlink">^ <a href="#cite_ref-Bury_249-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Bury_249-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBury1921" class="citation journal cs1"><a href="/wiki/Charles_Rugeley_Bury" title="Charles Rugeley Bury">Bury, Charles R.</a> (July 1921). <a rel="nofollow" class="external text" href="https://pubs.acs.org/doi/abs/10.1021/ja01440a023">"Langmuir's Theory of the Arrangement of Electrons in Atoms and Molecules"</a>. <i><a href="/wiki/Journal_of_the_American_Chemical_Society" title="Journal of the American Chemical Society">Journal of the American Chemical Society</a></i>. <b>43</b> (7): 1602–1609. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1021%2Fja01440a023">10.1021/ja01440a023</a>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0002-7863">0002-7863</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20211030145903/https://zenodo.org/record/1428812">Archived</a> from the original on 30 October 2021<span class="reference-accessdate">. Retrieved <span class="nowrap">22 October</span> 2021</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+of+the+American+Chemical+Society&rft.atitle=Langmuir%27s+Theory+of+the+Arrangement+of+Electrons+in+Atoms+and+Molecules&rft.volume=43&rft.issue=7&rft.pages=1602-1609&rft.date=1921-07&rft_id=info%3Adoi%2F10.1021%2Fja01440a023&rft.issn=0002-7863&rft.aulast=Bury&rft.aufirst=Charles+R.&rft_id=https%3A%2F%2Fpubs.acs.org%2Fdoi%2Fabs%2F10.1021%2Fja01440a023&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-Jensen2003-250"><span class="mw-cite-backlink"><b><a href="#cite_ref-Jensen2003_250-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFJensen2003" class="citation journal cs1">Jensen, William B. 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Retrieved <span class="nowrap">18 January</span> 2020</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Bloomberg+Businessweek&rft.atitle=Making+New+Elements+Doesn%27t+Pay.+Just+Ask+This+Berkeley+Scientist&rft.date=2019&rft.aulast=Subramanian&rft.aufirst=S.&rft_id=https%3A%2F%2Fwww.bloomberg.com%2Fnews%2Ffeatures%2F2019-08-28%2Fmaking-new-elements-doesn-t-pay-just-ask-this-berkeley-scientist&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-305"><span class="mw-cite-backlink"><b><a href="#cite_ref-305">^</a></b></span> <span class="reference-text">Scerri, p. 20</span> </li> <li id="cite_note-Papers-306"><span class="mw-cite-backlink"><b><a href="#cite_ref-Papers_306-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation book cs1"><a rel="nofollow" class="external text" href="https://othmerlib.sciencehistory.org/record=b1069103~S6"><i>Edward G. 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Retrieved <span class="nowrap">8 February</span> 2024</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Soviet+Physics+JETP&rft.atitle=n+%2B+%27+filling+rule+in+the+periodic+system+and+focusing+potentials.&rft.volume=35&rft.pages=66-69&rft.date=1972&rft.aulast=Demkov&rft.aufirst=YN&rft.au=Ostrovsky%2C+V&rft_id=http%3A%2F%2Fwww.jetp.ras.ru%2Fcgi-bin%2Fdn%2Fe_035_01_0066.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-313"><span class="mw-cite-backlink"><b><a href="#cite_ref-313">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFOstrovsky2005" class="citation journal cs1">Ostrovsky, V. N. (2005). "On Recent Discussion Concerning Quantum Justification of the Periodic Table of the Elements". <i>Foundations of Chemistry</i>. <b>7</b> (3): 235–239. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1007%2Fs10698-005-2141-y">10.1007/s10698-005-2141-y</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:93589189">93589189</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Foundations+of+Chemistry&rft.atitle=On+Recent+Discussion+Concerning+Quantum+Justification+of+the+Periodic+Table+of+the+Elements&rft.volume=7&rft.issue=3&rft.pages=235-239&rft.date=2005&rft_id=info%3Adoi%2F10.1007%2Fs10698-005-2141-y&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A93589189%23id-name%3DS2CID&rft.aulast=Ostrovsky&rft.aufirst=V.+N.&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-314"><span class="mw-cite-backlink"><b><a href="#cite_ref-314">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFScerri2012" class="citation journal cs1">Scerri, Eric (2012). <a rel="nofollow" class="external text" href="https://philpapers.org/archive/SCEWIA.pdf">"What is an element? What is the periodic table? And what does quantum mechanics contribute to the question?"</a> <span class="cs1-format">(PDF)</span>. <i>Foundations of Chemistry</i>. <b>14</b>: 69–81. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1007%2Fs10698-011-9124-y">10.1007/s10698-011-9124-y</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:254503469">254503469</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Foundations+of+Chemistry&rft.atitle=What+is+an+element%3F+What+is+the+periodic+table%3F+And+what+does+quantum+mechanics+contribute+to+the+question%3F&rft.volume=14&rft.pages=69-81&rft.date=2012&rft_id=info%3Adoi%2F10.1007%2Fs10698-011-9124-y&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A254503469%23id-name%3DS2CID&rft.aulast=Scerri&rft.aufirst=Eric&rft_id=https%3A%2F%2Fphilpapers.org%2Farchive%2FSCEWIA.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> <li id="cite_note-315"><span class="mw-cite-backlink"><b><a href="#cite_ref-315">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFScerri2021" class="citation journal cs1">Scerri, Eric (2021). "Various forms of the periodic table including the left-step table, the regularization of atomic number triads and first-member anomalies". <i>ChemTexts</i>. <b>8</b> (6). <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1007%2Fs40828-021-00157-8">10.1007/s40828-021-00157-8</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:245540088">245540088</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=ChemTexts&rft.atitle=Various+forms+of+the+periodic+table+including+the+left-step+table%2C+the+regularization+of+atomic+number+triads+and+first-member+anomalies&rft.volume=8&rft.issue=6&rft.date=2021&rft_id=info%3Adoi%2F10.1007%2Fs40828-021-00157-8&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A245540088%23id-name%3DS2CID&rft.aulast=Scerri&rft.aufirst=Eric&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></span> </li> </ol></div> <div class="mw-heading mw-heading2"><h2 id="Bibliography">Bibliography</h2></div> <style data-mw-deduplicate="TemplateStyles:r1239549316">.mw-parser-output .refbegin{margin-bottom:0.5em}.mw-parser-output .refbegin-hanging-indents>ul{margin-left:0}.mw-parser-output .refbegin-hanging-indents>ul>li{margin-left:0;padding-left:3.2em;text-indent:-3.2em}.mw-parser-output .refbegin-hanging-indents ul,.mw-parser-output .refbegin-hanging-indents ul li{list-style:none}@media(max-width:720px){.mw-parser-output .refbegin-hanging-indents>ul>li{padding-left:1.6em;text-indent:-1.6em}}.mw-parser-output .refbegin-columns{margin-top:0.3em}.mw-parser-output .refbegin-columns ul{margin-top:0}.mw-parser-output .refbegin-columns li{page-break-inside:avoid;break-inside:avoid-column}@media screen{.mw-parser-output .refbegin{font-size:90%}}</style><div class="refbegin" style=""> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFGreenwoodEarnshaw1997" class="citation book cs1"><a href="/wiki/Norman_Greenwood" title="Norman Greenwood">Greenwood, Norman N.</a>; Earnshaw, Alan (1997). <i>Chemistry of the Elements</i> (2nd ed.). <a href="/wiki/Butterworth-Heinemann" title="Butterworth-Heinemann">Butterworth-Heinemann</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-08-037941-8" title="Special:BookSources/978-0-08-037941-8"><bdi>978-0-08-037941-8</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Chemistry+of+the+Elements&rft.edition=2nd&rft.pub=Butterworth-Heinemann&rft.date=1997&rft.isbn=978-0-08-037941-8&rft.aulast=Greenwood&rft.aufirst=Norman+N.&rft.au=Earnshaw%2C+Alan&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFPetrucciHarwoodHerring2002" class="citation book cs1">Petrucci, Ralph H.; Harwood, William S.; Herring, F. Geoffrey (2002). <span class="id-lock-registration" title="Free registration required"><a rel="nofollow" class="external text" href="https://archive.org/details/generalchemistry00hill"><i>General chemistry: principles and modern applications</i></a></span> (8th ed.). Upper Saddle River, N.J.: Prentice Hall. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-13-014329-7" title="Special:BookSources/978-0-13-014329-7"><bdi>978-0-13-014329-7</bdi></a>. <a href="/wiki/LCCN_(identifier)" class="mw-redirect" title="LCCN (identifier)">LCCN</a> <a rel="nofollow" class="external text" href="https://lccn.loc.gov/2001032331">2001032331</a>. <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/46872308">46872308</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=General+chemistry%3A+principles+and+modern+applications&rft.place=Upper+Saddle+River%2C+N.J.&rft.edition=8th&rft.pub=Prentice+Hall&rft.date=2002&rft_id=info%3Aoclcnum%2F46872308&rft_id=info%3Alccn%2F2001032331&rft.isbn=978-0-13-014329-7&rft.aulast=Petrucci&rft.aufirst=Ralph+H.&rft.au=Harwood%2C+William+S.&rft.au=Herring%2C+F.+Geoffrey&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fgeneralchemistry00hill&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFSiekierskiBurgess2002" class="citation book cs1">Siekierski, S.; Burgess, J. (2002). <i>Concise Chemistry of the Elements</i>. Horwood. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-898563-71-6" title="Special:BookSources/978-1-898563-71-6"><bdi>978-1-898563-71-6</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Concise+Chemistry+of+the+Elements&rft.pub=Horwood&rft.date=2002&rft.isbn=978-1-898563-71-6&rft.aulast=Siekierski&rft.aufirst=S.&rft.au=Burgess%2C+J.&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></li> <li><a href="/wiki/Eric_Scerri" title="Eric Scerri">Scerri, Eric R</a> (2020). <i>The Periodic Table, Its Story and Its Significance</i> (2nd ed.). Oxford University Press, New York, <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-19-091436-3" title="Special:BookSources/978-0-19-091436-3">978-0-19-091436-3</a>.</li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWulfsberg2000" class="citation book cs1">Wulfsberg, Gary (2000). <i>Inorganic Chemistry</i>. University Science Books. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9781891389016" title="Special:BookSources/9781891389016"><bdi>9781891389016</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Inorganic+Chemistry&rft.pub=University+Science+Books&rft.date=2000&rft.isbn=9781891389016&rft.aulast=Wulfsberg&rft.aufirst=Gary&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></li></ul> </div> <div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239549316"><div class="refbegin" style=""> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFCalvo2019" class="citation book cs1">Calvo, Miguel (2019). <i>Construyendo la Tabla Periódica</i>. Zaragoza, Spain: Prames. p. 407. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-84-8321-908-9" title="Special:BookSources/978-84-8321-908-9"><bdi>978-84-8321-908-9</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Construyendo+la+Tabla+Peri%C3%B3dica&rft.place=Zaragoza%2C+Spain&rft.pages=407&rft.pub=Prames&rft.date=2019&rft.isbn=978-84-8321-908-9&rft.aulast=Calvo&rft.aufirst=Miguel&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFEmsley2011" class="citation book cs1"><a href="/wiki/John_Emsley" title="John Emsley">Emsley, J.</a> (2011). "The Periodic Table". <i>Nature's Building Blocks: An A–Z Guide to the Elements</i> (New ed.). Oxford: Oxford University Press. pp. 634–651. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-19-960563-7" title="Special:BookSources/978-0-19-960563-7"><bdi>978-0-19-960563-7</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=The+Periodic+Table&rft.btitle=Nature%27s+Building+Blocks%3A+An+A%E2%80%93Z+Guide+to+the+Elements&rft.place=Oxford&rft.pages=634-651&rft.edition=New&rft.pub=Oxford+University+Press&rft.date=2011&rft.isbn=978-0-19-960563-7&rft.aulast=Emsley&rft.aufirst=J.&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFFontaniCostaOrna2007" class="citation book cs1">Fontani, Marco; Costa, Mariagrazia; Orna, Mary Virginia (2007). <i>The Lost Elements: The Periodic Table's Shadow Side</i>. Oxford: Oxford University Press. p. 508. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-19-938334-4" title="Special:BookSources/978-0-19-938334-4"><bdi>978-0-19-938334-4</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Lost+Elements%3A+The+Periodic+Table%27s+Shadow+Side&rft.place=Oxford&rft.pages=508&rft.pub=Oxford+University+Press&rft.date=2007&rft.isbn=978-0-19-938334-4&rft.aulast=Fontani&rft.aufirst=Marco&rft.au=Costa%2C+Mariagrazia&rft.au=Orna%2C+Mary+Virginia&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMazurs1974" class="citation book cs1"><a href="/wiki/John_Emsley" title="John Emsley">Mazurs, E. G.</a> (1974). <i>Graphic Representations of the Periodic System During One Hundred Years</i>. Alabama: University of Alabama Press. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-19-960563-7" title="Special:BookSources/978-0-19-960563-7"><bdi>978-0-19-960563-7</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Graphic+Representations+of+the+Periodic+System+During+One+Hundred+Years&rft.place=Alabama&rft.pub=University+of+Alabama+Press&rft.date=1974&rft.isbn=978-0-19-960563-7&rft.aulast=Mazurs&rft.aufirst=E.+G.&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFRouvrayKing2004" class="citation conference cs1">Rouvray, D.H.; King, R. B., eds. (2004). <i>The Periodic Table: Into the 21st Century</i>. Proceedings of the 2nd International Conference on the Periodic Table, part 1, Kananaskis Guest Ranch, Alberta, 14–20 July 2003. Baldock, Hertfordshire: Research Studies Press. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-86380-292-8" title="Special:BookSources/978-0-86380-292-8"><bdi>978-0-86380-292-8</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=conference&rft.btitle=The+Periodic+Table%3A+Into+the+21st+Century&rft.place=Baldock%2C+Hertfordshire&rft.pub=Research+Studies+Press&rft.date=2004&rft.isbn=978-0-86380-292-8&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFRouvrayKing2006" class="citation conference cs1">Rouvray, D.H.; King, R. B., eds. (2006). <i>The Mathematics of the Periodic Table</i>. Proceedings of the 2nd International Conference on the Periodic Table, part 2, Kananaskis Guest Ranch, Alberta, 14–20 July 2003. New York: Nova Science. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-59454-259-6" title="Special:BookSources/978-1-59454-259-6"><bdi>978-1-59454-259-6</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=conference&rft.btitle=The+Mathematics+of+the+Periodic+Table&rft.place=New+York&rft.pub=Nova+Science&rft.date=2006&rft.isbn=978-1-59454-259-6&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFScerrin.d." class="citation web cs1">Scerri, E (n.d.). <a rel="nofollow" class="external text" href="https://www.ericscerri.com/books_elements.pdf">"Books on the Elements and the Periodic Table"</a> <span class="cs1-format">(PDF)</span>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20200811052254/https://www.ericscerri.com/books_elements.pdf">Archived</a> <span class="cs1-format">(PDF)</span> from the original on 11 August 2020<span class="reference-accessdate">. Retrieved <span class="nowrap">9 July</span> 2018</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Books+on+the+Elements+and+the+Periodic+Table&rft.aulast=Scerri&rft.aufirst=E&rft_id=https%3A%2F%2Fwww.ericscerri.com%2Fbooks_elements.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFScerriRestrepo2018" class="citation conference cs1">Scerri, E.; Restrepo, G, eds. (2018). <i>Mendeleev to Oganesson: A Multidisciplinary Perspective on the Periodic Table</i>. Proceedings of the 3rd International Conference on the Periodic Table, Cuzco, Peru 14–16 August 2012. Oxford: Oxford University Press. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-86380-292-8" title="Special:BookSources/978-0-86380-292-8"><bdi>978-0-86380-292-8</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=conference&rft.btitle=Mendeleev+to+Oganesson%3A+A+Multidisciplinary+Perspective+on+the+Periodic+Table&rft.place=Oxford&rft.pub=Oxford+University+Press&rft.date=2018&rft.isbn=978-0-86380-292-8&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFvan_Spronsen1969" class="citation book cs1">van Spronsen, J. W. (1969). <i>The Periodic System of Chemical Elements: A History of the First Hundred Years</i>. Amsterdam: Elsevier. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-444-40776-4" title="Special:BookSources/978-0-444-40776-4"><bdi>978-0-444-40776-4</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Periodic+System+of+Chemical+Elements%3A+A+History+of+the+First+Hundred+Years&rft.place=Amsterdam&rft.pub=Elsevier&rft.date=1969&rft.isbn=978-0-444-40776-4&rft.aulast=van+Spronsen&rft.aufirst=J.+W.&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFVerde1971" class="citation conference cs1">Verde, M., ed. (1971). <i>Atti del convegno Mendeleeviano: Periodicità e simmetrie nella struttura elementare della materia</i> [<i>Proceedings of the Mendeleevian conference: Periodicity and symmetry in the elementary structure of matter</i>]. 1st International Conference on the Periodic Table, Torino-Roma, 15–21 September 1969. Torino: Accademia delle Scienze di Torino.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=conference&rft.btitle=Atti+del+convegno+Mendeleeviano%3A+Periodicit%C3%A0+e+simmetrie+nella+struttura+elementare+della+materia&rft.place=Torino&rft.pub=Accademia+delle+Scienze+di+Torino&rft.date=1971&rfr_id=info%3Asid%2Fen.wikipedia.org%3APeriodic+table" class="Z3988"></span></li></ul> </div> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2></div> <style data-mw-deduplicate="TemplateStyles:r1235681985">.mw-parser-output .side-box{margin:4px 0;box-sizing:border-box;border:1px solid #aaa;font-size:88%;line-height:1.25em;background-color:var(--background-color-interactive-subtle,#f8f9fa);display:flow-root}.mw-parser-output .side-box-abovebelow,.mw-parser-output .side-box-text{padding:0.25em 0.9em}.mw-parser-output .side-box-image{padding:2px 0 2px 0.9em;text-align:center}.mw-parser-output .side-box-imageright{padding:2px 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src="//upload.wikimedia.org/wikipedia/en/thumb/0/06/Wiktionary-logo-v2.svg/27px-Wiktionary-logo-v2.svg.png" decoding="async" width="27" height="27" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/0/06/Wiktionary-logo-v2.svg/41px-Wiktionary-logo-v2.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/0/06/Wiktionary-logo-v2.svg/54px-Wiktionary-logo-v2.svg.png 2x" data-file-width="391" data-file-height="391" /></span></span></span><span class="sister-link"><a href="https://en.wiktionary.org/wiki/Special:Search/Periodic_table" class="extiw" title="wikt:Special:Search/Periodic table">Definitions</a> from Wiktionary</span></li><li><span class="sister-logo"><span class="mw-valign-middle" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/20px-Commons-logo.svg.png" decoding="async" width="20" height="27" class="mw-file-element" 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typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Wikisource-logo.svg/26px-Wikisource-logo.svg.png" decoding="async" width="26" height="27" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Wikisource-logo.svg/39px-Wikisource-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Wikisource-logo.svg/51px-Wikisource-logo.svg.png 2x" data-file-width="410" data-file-height="430" /></span></span></span><span class="sister-link"><a href="https://en.wikisource.org/wiki/Special:Search/Periodic_table" class="extiw" title="s:Special:Search/Periodic table">Texts</a> from Wikisource</span></li><li><span class="sister-logo"><span class="mw-valign-middle" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/f/fa/Wikibooks-logo.svg/27px-Wikibooks-logo.svg.png" decoding="async" width="27" height="27" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/fa/Wikibooks-logo.svg/41px-Wikibooks-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/fa/Wikibooks-logo.svg/54px-Wikibooks-logo.svg.png 2x" data-file-width="300" data-file-height="300" /></span></span></span><span class="sister-link"><a href="https://en.wikibooks.org/wiki/General_Chemistry/Periodic_Table" class="extiw" title="b:General Chemistry/Periodic Table">Textbooks</a> from Wikibooks</span></li><li><span class="sister-logo"><span class="mw-valign-middle" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/0/0b/Wikiversity_logo_2017.svg/27px-Wikiversity_logo_2017.svg.png" decoding="async" width="27" height="22" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/0b/Wikiversity_logo_2017.svg/41px-Wikiversity_logo_2017.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/0b/Wikiversity_logo_2017.svg/54px-Wikiversity_logo_2017.svg.png 2x" data-file-width="626" data-file-height="512" /></span></span></span><span class="sister-link"><a href="https://en.wikiversity.org/wiki/The_periodic_table" class="extiw" title="v:The periodic table">Resources</a> from Wikiversity</span></li></ul></div></div> </div> <ul><li><a rel="nofollow" class="external text" href="https://digital.sciencehistory.org/focus/periodic-tables">Periodic Table</a> featured topic page on <a href="/wiki/Science_History_Institute" title="Science History Institute">Science History Institute</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20190202042542/https://digital.sciencehistory.org/">Digital Collections</a> featuring select visual representations of the periodic table of the elements, with an emphasis on alternative layouts including circular, cylindrical, pyramidal, spiral, and triangular forms.</li> <li><a rel="nofollow" class="external text" href="https://iupac.org/what-we-do/periodic-table-of-elements">IUPAC Periodic Table of the Elements</a></li> <li><a rel="nofollow" class="external text" href="https://www.ptable.com/">Dynamic periodic table</a>, with interactive layouts</li> <li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20131014171011/https://www.ericscerri.com/">Eric Scerri</a>, leading philosopher of science specializing in the history and philosophy of the periodic table</li> <li><a rel="nofollow" class="external text" href="https://www.meta-synthesis.com/webbook//35_pt/pt_database.php">The Internet Database of Periodic Tables</a></li> <li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20180112160406/https://www.acs.org/content/acs/en/greenchemistry/research-innovation/research-topics/endangered-elements.html">Periodic table of endangered elements</a></li> <li><a rel="nofollow" class="external text" href="https://periodictable.com">Periodic table of samples</a></li> <li><a rel="nofollow" class="external text" href="https://periodicvideos.com">Periodic table of videos</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20230703042907/https://www.periodicvideos.com/">Archived</a> 3 July 2023 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a></li> <li><a rel="nofollow" class="external text" href="https://webelements.com">WebElements</a></li> <li><a rel="nofollow" class="external text" href="https://www.periodicgraphicsofelements.com/">The Periodic Graphics of Elements</a></li></ul> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1236075235">.mw-parser-output .navbox{box-sizing:border-box;border:1px solid #a2a9b1;width:100%;clear:both;font-size:88%;text-align:center;padding:1px;margin:1em auto 0}.mw-parser-output .navbox .navbox{margin-top:0}.mw-parser-output .navbox+.navbox,.mw-parser-output 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.navbox-title{background-color:#ddf}.mw-parser-output .navbox-subgroup .navbox-group,.mw-parser-output .navbox-subgroup .navbox-abovebelow{background-color:#e6e6ff}.mw-parser-output .navbox-even{background-color:#f7f7f7}.mw-parser-output .navbox-odd{background-color:transparent}.mw-parser-output .navbox .hlist td dl,.mw-parser-output .navbox .hlist td ol,.mw-parser-output .navbox .hlist td ul,.mw-parser-output .navbox td.hlist dl,.mw-parser-output .navbox td.hlist ol,.mw-parser-output .navbox td.hlist ul{padding:0.125em 0}.mw-parser-output .navbox .navbar{display:block;font-size:100%}.mw-parser-output .navbox-title .navbar{float:left;text-align:left;margin-right:0.5em}body.skin--responsive .mw-parser-output .navbox-image img{max-width:none!important}@media print{body.ns-0 .mw-parser-output .navbox{display:none!important}}</style></div><div role="navigation" class="navbox" aria-labelledby="Periodic_table" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Periodic_table_(navbox)" title="Template:Periodic table (navbox)"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Periodic_table_(navbox)" title="Template talk:Periodic table (navbox)"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Periodic_table_(navbox)" title="Special:EditPage/Template:Periodic table (navbox)"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Periodic_table" style="font-size:114%;margin:0 4em"><a class="mw-selflink selflink">Periodic table</a></div></th></tr><tr><td colspan="2" class="navbox-list navbox-odd wraplinks" style="width:100%;padding:0"><div style="padding:0 0.25em"> <table style="table-layout:fixed; width:100%;" aria-describedby="periodic-table-legend"> <tbody><tr> <td style="line-height:100%;"> </td> <th scope="col" style="background:transparent; font-weight:normal;"><a href="/wiki/Alkali_metal" title="Alkali metal">1</a> </th> <th scope="col" style="background:transparent; font-weight:normal;"><a href="/wiki/Alkaline_earth_metal" title="Alkaline earth metal">2</a> </th> <td colspan="14"> </td> <th scope="col" style="background:transparent; font-weight:normal;"><a href="/wiki/Group_3_element" title="Group 3 element">3</a> </th> <th scope="col" style="background:transparent; font-weight:normal;"><a href="/wiki/Group_4_element" title="Group 4 element">4</a> </th> <th scope="col" style="background:transparent; font-weight:normal;"><a href="/wiki/Group_5_element" title="Group 5 element">5</a> </th> <th scope="col" style="background:transparent; font-weight:normal;"><a href="/wiki/Group_6_element" title="Group 6 element">6</a> </th> <th scope="col" style="background:transparent; font-weight:normal;"><a href="/wiki/Group_7_element" title="Group 7 element">7</a> </th> <th scope="col" style="background:transparent; font-weight:normal;"><a href="/wiki/Group_8_element" title="Group 8 element">8</a> </th> <th scope="col" style="background:transparent; font-weight:normal;"><a href="/wiki/Group_9_element" title="Group 9 element">9</a> </th> <th scope="col" style="background:transparent; font-weight:normal;"><a href="/wiki/Group_10_element" title="Group 10 element">10</a> </th> <th scope="col" style="background:transparent; font-weight:normal;"><a href="/wiki/Group_11_element" title="Group 11 element">11</a> </th> <th scope="col" style="background:transparent; font-weight:normal;"><a href="/wiki/Group_12_element" title="Group 12 element">12</a> </th> <th scope="col" style="background:transparent; font-weight:normal;"><a href="/wiki/Boron_group" title="Boron group">13</a> </th> <th scope="col" style="background:transparent; font-weight:normal;"><a href="/wiki/Carbon_group" title="Carbon group">14</a> </th> <th scope="col" style="background:transparent; font-weight:normal;"><a href="/wiki/Pnictogen" title="Pnictogen">15</a> </th> <th scope="col" style="background:transparent; font-weight:normal;"><a href="/wiki/Chalcogen" title="Chalcogen">16</a> </th> <th scope="col" style="background:transparent; font-weight:normal;"><a href="/wiki/Halogen" title="Halogen">17</a> </th> <th scope="col" style="background:transparent; font-weight:normal;"><a href="/wiki/Noble_gas" title="Noble gas">18</a> </th></tr> <tr> <th scope="row" style="background:transparent; font-weight:normal;"><a href="/wiki/Period_1_element" title="Period 1 element">1</a> </th> <td title="H, Hydrogen" style="text-align:center; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Hydrogen" title="Hydrogen"><span style="display:block">H</span></a></span> </td> <td colspan="30"> </td> <td title="He, Helium" style="text-align:center; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Helium" title="Helium"><span style="display:block">He</span></a></span> </td></tr> <tr> <th scope="row" style="background:transparent; font-weight:normal;"><a href="/wiki/Period_2_element" title="Period 2 element">2</a> </th> <td title="Li, Lithium" style="text-align:center; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Lithium" title="Lithium"><span style="display:block">Li</span></a></span> </td> <td title="Be, Beryllium" style="text-align:center; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Beryllium" title="Beryllium"><span style="display:block">Be</span></a></span> </td> <td colspan="24"> </td> <td title="B, Boron" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Boron" title="Boron"><span style="display:block">B</span></a></span> </td> <td title="C, Carbon" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Carbon" title="Carbon"><span style="display:block">C</span></a></span> </td> <td title="N, Nitrogen" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Nitrogen" title="Nitrogen"><span style="display:block">N</span></a></span> </td> <td title="O, Oxygen" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Oxygen" title="Oxygen"><span style="display:block">O</span></a></span> </td> <td title="F, Fluorine" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Fluorine" title="Fluorine"><span style="display:block">F</span></a></span> </td> <td title="Ne, Neon" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Neon" title="Neon"><span style="display:block">Ne</span></a></span> </td></tr> <tr> <th scope="row" style="background:transparent; font-weight:normal;"><a href="/wiki/Period_3_element" title="Period 3 element">3</a> </th> <td title="Na, Sodium" style="text-align:center; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Sodium" title="Sodium"><span style="display:block">Na</span></a></span> </td> <td title="Mg, Magnesium" style="text-align:center; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Magnesium" title="Magnesium"><span style="display:block">Mg</span></a></span> </td> <td colspan="24"> </td> <td title="Al, Aluminium" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Aluminium" title="Aluminium"><span style="display:block">Al</span></a></span> </td> <td title="Si, Silicon" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Silicon" title="Silicon"><span style="display:block">Si</span></a></span> </td> <td title="P, Phosphorus" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Phosphorus" title="Phosphorus"><span style="display:block">P</span></a></span> </td> <td title="S, Sulfur" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Sulfur" title="Sulfur"><span style="display:block">S</span></a></span> </td> <td title="Cl, Chlorine" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Chlorine" title="Chlorine"><span style="display:block">Cl</span></a></span> </td> <td title="Ar, Argon" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Argon" title="Argon"><span style="display:block">Ar</span></a></span> </td></tr> <tr> <th scope="row" style="background:transparent; font-weight:normal;"><a href="/wiki/Period_4_element" title="Period 4 element">4</a> </th> <td title="K, Potassium" style="text-align:center; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Potassium" title="Potassium"><span style="display:block">K</span></a></span> </td> <td title="Ca, Calcium" style="text-align:center; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Calcium" title="Calcium"><span style="display:block">Ca</span></a></span> </td> <td colspan="14"> </td> <td title="Sc, Scandium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Scandium" title="Scandium"><span style="display:block">Sc</span></a></span> </td> <td title="Ti, Titanium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Titanium" title="Titanium"><span style="display:block">Ti</span></a></span> </td> <td title="V, Vanadium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Vanadium" title="Vanadium"><span style="display:block">V</span></a></span> </td> <td title="Cr, Chromium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Chromium" title="Chromium"><span style="display:block">Cr</span></a></span> </td> <td title="Mn, Manganese" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Manganese" title="Manganese"><span style="display:block">Mn</span></a></span> </td> <td title="Fe, Iron" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Iron" title="Iron"><span style="display:block">Fe</span></a></span> </td> <td title="Co, Cobalt" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Cobalt" title="Cobalt"><span style="display:block">Co</span></a></span> </td> <td title="Ni, Nickel" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Nickel" title="Nickel"><span style="display:block">Ni</span></a></span> </td> <td title="Cu, Copper" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Copper" title="Copper"><span style="display:block">Cu</span></a></span> </td> <td title="Zn, Zinc" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Zinc" title="Zinc"><span style="display:block">Zn</span></a></span> </td> <td title="Ga, Gallium" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Gallium" title="Gallium"><span style="display:block">Ga</span></a></span> </td> <td title="Ge, Germanium" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Germanium" title="Germanium"><span style="display:block">Ge</span></a></span> </td> <td title="As, Arsenic" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Arsenic" title="Arsenic"><span style="display:block">As</span></a></span> </td> <td title="Se, Selenium" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Selenium" title="Selenium"><span style="display:block">Se</span></a></span> </td> <td title="Br, Bromine" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Bromine" title="Bromine"><span style="display:block">Br</span></a></span> </td> <td title="Kr, Krypton" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Krypton" title="Krypton"><span style="display:block">Kr</span></a></span> </td></tr> <tr> <th scope="row" style="background:transparent; font-weight:normal;"><a href="/wiki/Period_5_element" title="Period 5 element">5</a> </th> <td title="Rb, Rubidium" style="text-align:center; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Rubidium" title="Rubidium"><span style="display:block">Rb</span></a></span> </td> <td title="Sr, Strontium" style="text-align:center; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Strontium" title="Strontium"><span style="display:block">Sr</span></a></span> </td> <td colspan="14"> </td> <td title="Y, Yttrium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Yttrium" title="Yttrium"><span style="display:block">Y</span></a></span> </td> <td title="Zr, Zirconium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Zirconium" title="Zirconium"><span style="display:block">Zr</span></a></span> </td> <td title="Nb, Niobium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Niobium" title="Niobium"><span style="display:block">Nb</span></a></span> </td> <td title="Mo, Molybdenum" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Molybdenum" title="Molybdenum"><span style="display:block">Mo</span></a></span> </td> <td title="Tc, Technetium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Technetium" title="Technetium"><span style="display:block">Tc</span></a></span> </td> <td title="Ru, Ruthenium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Ruthenium" title="Ruthenium"><span style="display:block">Ru</span></a></span> </td> <td title="Rh, Rhodium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Rhodium" title="Rhodium"><span style="display:block">Rh</span></a></span> </td> <td title="Pd, Palladium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Palladium" title="Palladium"><span style="display:block">Pd</span></a></span> </td> <td title="Ag, Silver" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Silver" title="Silver"><span style="display:block">Ag</span></a></span> </td> <td title="Cd, Cadmium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Cadmium" title="Cadmium"><span style="display:block">Cd</span></a></span> </td> <td title="In, Indium" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Indium" title="Indium"><span style="display:block">In</span></a></span> </td> <td title="Sn, Tin" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Tin" title="Tin"><span style="display:block">Sn</span></a></span> </td> <td title="Sb, Antimony" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Antimony" title="Antimony"><span style="display:block">Sb</span></a></span> </td> <td title="Te, Tellurium" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Tellurium" title="Tellurium"><span style="display:block">Te</span></a></span> </td> <td title="I, Iodine" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Iodine" title="Iodine"><span style="display:block">I</span></a></span> </td> <td title="Xe, Xenon" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Xenon" title="Xenon"><span style="display:block">Xe</span></a></span> </td></tr> <tr> <th scope="row" style="background:transparent; font-weight:normal;"><a href="/wiki/Period_6_element" title="Period 6 element">6</a> </th> <td title="Cs, Caesium" style="text-align:center; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Caesium" title="Caesium"><span style="display:block">Cs</span></a></span> </td> <td title="Ba, Barium" style="text-align:center; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Barium" title="Barium"><span style="display:block">Ba</span></a></span> </td> <td title="La, Lanthanum" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Lanthanum" title="Lanthanum"><span style="display:block">La</span></a></span> </td> <td title="Ce, Cerium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Cerium" title="Cerium"><span style="display:block">Ce</span></a></span> </td> <td title="Pr, Praseodymium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Praseodymium" title="Praseodymium"><span style="display:block">Pr</span></a></span> </td> <td title="Nd, Neodymium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Neodymium" title="Neodymium"><span style="display:block">Nd</span></a></span> </td> <td title="Pm, Promethium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Promethium" title="Promethium"><span style="display:block">Pm</span></a></span> </td> <td title="Sm, Samarium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Samarium" title="Samarium"><span style="display:block">Sm</span></a></span> </td> <td title="Eu, Europium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Europium" title="Europium"><span style="display:block">Eu</span></a></span> </td> <td title="Gd, Gadolinium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Gadolinium" title="Gadolinium"><span style="display:block">Gd</span></a></span> </td> <td title="Tb, Terbium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Terbium" title="Terbium"><span style="display:block">Tb</span></a></span> </td> <td title="Dy, Dysprosium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Dysprosium" title="Dysprosium"><span style="display:block">Dy</span></a></span> </td> <td title="Ho, Holmium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Holmium" title="Holmium"><span style="display:block">Ho</span></a></span> </td> <td title="Er, Erbium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Erbium" title="Erbium"><span style="display:block">Er</span></a></span> </td> <td title="Tm, Thulium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Thulium" title="Thulium"><span style="display:block">Tm</span></a></span> </td> <td title="Yb, Ytterbium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Ytterbium" title="Ytterbium"><span style="display:block">Yb</span></a></span> </td> <td title="Lu, Lutetium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Lutetium" title="Lutetium"><span style="display:block">Lu</span></a></span> </td> <td title="Hf, Hafnium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Hafnium" title="Hafnium"><span style="display:block">Hf</span></a></span> </td> <td title="Ta, Tantalum" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Tantalum" title="Tantalum"><span style="display:block">Ta</span></a></span> </td> <td title="W, Tungsten" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Tungsten" title="Tungsten"><span style="display:block">W</span></a></span> </td> <td title="Re, Rhenium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Rhenium" title="Rhenium"><span style="display:block">Re</span></a></span> </td> <td title="Os, Osmium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Osmium" title="Osmium"><span style="display:block">Os</span></a></span> </td> <td title="Ir, Iridium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Iridium" title="Iridium"><span style="display:block">Ir</span></a></span> </td> <td title="Pt, Platinum" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Platinum" title="Platinum"><span style="display:block">Pt</span></a></span> </td> <td title="Au, Gold" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Gold" title="Gold"><span style="display:block">Au</span></a></span> </td> <td title="Hg, Mercury" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Mercury_(element)" title="Mercury (element)"><span style="display:block">Hg</span></a></span> </td> <td title="Tl, Thallium" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Thallium" title="Thallium"><span style="display:block">Tl</span></a></span> </td> <td title="Pb, Lead" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Lead" title="Lead"><span style="display:block">Pb</span></a></span> </td> <td title="Bi, Bismuth" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Bismuth" title="Bismuth"><span style="display:block">Bi</span></a></span> </td> <td title="Po, Polonium" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Polonium" title="Polonium"><span style="display:block">Po</span></a></span> </td> <td title="At, Astatine" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Astatine" title="Astatine"><span style="display:block">At</span></a></span> </td> <td title="Rn, Radon" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Radon" title="Radon"><span style="display:block">Rn</span></a></span> </td></tr> <tr> <th scope="row" style="background:transparent; font-weight:normal;"><a href="/wiki/Period_7_element" title="Period 7 element">7</a> </th> <td title="Fr, Francium" style="text-align:center; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Francium" title="Francium"><span style="display:block">Fr</span></a></span> </td> <td title="Ra, Radium" style="text-align:center; background-color:#ff9999; border:none; ;"><span class="nowrap"><a href="/wiki/Radium" title="Radium"><span style="display:block">Ra</span></a></span> </td> <td title="Ac, Actinium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Actinium" title="Actinium"><span style="display:block">Ac</span></a></span> </td> <td title="Th, Thorium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Thorium" title="Thorium"><span style="display:block">Th</span></a></span> </td> <td title="Pa, Protactinium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Protactinium" title="Protactinium"><span style="display:block">Pa</span></a></span> </td> <td title="U, Uranium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Uranium" title="Uranium"><span style="display:block">U</span></a></span> </td> <td title="Np, Neptunium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Neptunium" title="Neptunium"><span style="display:block">Np</span></a></span> </td> <td title="Pu, Plutonium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Plutonium" title="Plutonium"><span style="display:block">Pu</span></a></span> </td> <td title="Am, Americium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Americium" title="Americium"><span style="display:block">Am</span></a></span> </td> <td title="Cm, Curium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Curium" title="Curium"><span style="display:block">Cm</span></a></span> </td> <td title="Bk, Berkelium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Berkelium" title="Berkelium"><span style="display:block">Bk</span></a></span> </td> <td title="Cf, Californium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Californium" title="Californium"><span style="display:block">Cf</span></a></span> </td> <td title="Es, Einsteinium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Einsteinium" title="Einsteinium"><span style="display:block">Es</span></a></span> </td> <td title="Fm, Fermium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Fermium" title="Fermium"><span style="display:block">Fm</span></a></span> </td> <td title="Md, Mendelevium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Mendelevium" title="Mendelevium"><span style="display:block">Md</span></a></span> </td> <td title="No, Nobelium" style="text-align:center; background-color:#9bff99; border:none; ;"><span class="nowrap"><a href="/wiki/Nobelium" title="Nobelium"><span style="display:block">No</span></a></span> </td> <td title="Lr, Lawrencium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Lawrencium" title="Lawrencium"><span style="display:block">Lr</span></a></span> </td> <td title="Rf, Rutherfordium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Rutherfordium" title="Rutherfordium"><span style="display:block">Rf</span></a></span> </td> <td title="Db, Dubnium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Dubnium" title="Dubnium"><span style="display:block">Db</span></a></span> </td> <td title="Sg, Seaborgium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Seaborgium" title="Seaborgium"><span style="display:block">Sg</span></a></span> </td> <td title="Bh, Bohrium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Bohrium" title="Bohrium"><span style="display:block">Bh</span></a></span> </td> <td title="Hs, Hassium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Hassium" title="Hassium"><span style="display:block">Hs</span></a></span> </td> <td title="Mt, Meitnerium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Meitnerium" title="Meitnerium"><span style="display:block">Mt</span></a></span> </td> <td title="Ds, Darmstadtium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Darmstadtium" title="Darmstadtium"><span style="display:block">Ds</span></a></span> </td> <td title="Rg, Roentgenium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Roentgenium" title="Roentgenium"><span style="display:block">Rg</span></a></span> </td> <td title="Cn, Copernicium" style="text-align:center; background-color:#99ccff; border:none; ;"><span class="nowrap"><a href="/wiki/Copernicium" title="Copernicium"><span style="display:block">Cn</span></a></span> </td> <td title="Nh, Nihonium" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Nihonium" title="Nihonium"><span style="display:block">Nh</span></a></span> </td> <td title="Fl, Flerovium" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Flerovium" title="Flerovium"><span style="display:block">Fl</span></a></span> </td> <td title="Mc, Moscovium" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Moscovium" title="Moscovium"><span style="display:block">Mc</span></a></span> </td> <td title="Lv, Livermorium" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Livermorium" title="Livermorium"><span style="display:block">Lv</span></a></span> </td> <td title="Ts, Tennessine" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Tennessine" title="Tennessine"><span style="display:block">Ts</span></a></span> </td> <td title="Og, Oganesson" style="text-align:center; background-color:#fdff8c; border:none; ;"><span class="nowrap"><a href="/wiki/Oganesson" title="Oganesson"><span style="display:block">Og</span></a></span> </td></tr></tbody></table> </div></td></tr><tr><td colspan="2" class="navbox-list navbox-even wraplinks" style="width:100%;padding:0"><div style="padding:0 0.25em"><div role="presentation" id="periodic-table-legend" style="border: 1px solid #a2a9b1; width:100%; line-height:120%; text-align:center; vertical-align:top; background:#f8f8f8; margin:0; margin:0;"><div style="padding:0.3em;"> <table style="width:100%; line-height:1.2em; table-layout:fixed; overflow:hidden; text-align:center;"> <tbody><tr> <td style="padding:0 1px; background:#ff9999;"><a href="/wiki/S-block" class="mw-redirect" title="S-block">s-block</a> </td> <td style="padding:0 1px; background:#9bff99;"><a href="/wiki/F-block" class="mw-redirect" title="F-block">f-block</a> </td> <td style="padding:0 1px; background:#99ccff;"><a href="/wiki/D-block" class="mw-redirect" title="D-block">d-block</a> </td> <td style="padding:0 1px; background:#fdff8c;"><a href="/wiki/P-block" class="mw-redirect" title="P-block">p-block</a> </td></tr></tbody></table> </div> </div></div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="Periodic_table" style="padding:3px"><table class="nowraplinks hlist mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Navbox_periodic_table" title="Template:Navbox periodic table"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Navbox_periodic_table" title="Template talk:Navbox periodic table"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Navbox_periodic_table" title="Special:EditPage/Template:Navbox periodic table"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Periodic_table" style="font-size:114%;margin:0 4em"><a class="mw-selflink selflink">Periodic table</a></div></th></tr><tr><th scope="row" class="navbox-group wraplinks" style="width:1%;white-space: normal !important;">Periodic table forms</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Types_of_periodic_tables" title="Types of periodic tables">Alternatives</a></li> <li><a href="/wiki/Extended_periodic_table" title="Extended periodic table">Extended periodic table</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group wraplinks" style="width:1%;white-space: normal !important;"><a href="/wiki/Names_for_sets_of_chemical_elements" title="Names for sets of chemical elements">Sets of elements</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%;white-space: normal !important;">By periodic table structure</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Group_(periodic_table)" title="Group (periodic table)">Groups</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Alkali_metal" title="Alkali metal">1 (Hydrogen and alkali metals)</a></li> <li><a href="/wiki/Alkaline_earth_metal" title="Alkaline earth metal">2 (Alkaline earth metals)</a></li> <li><a href="/wiki/Group_3_element" title="Group 3 element">3</a></li> <li><a href="/wiki/Group_4_element" title="Group 4 element">4</a></li> <li><a href="/wiki/Group_5_element" title="Group 5 element">5</a></li> <li><a href="/wiki/Group_6_element" title="Group 6 element">6</a></li> <li><a href="/wiki/Group_7_element" title="Group 7 element">7</a></li> <li><a href="/wiki/Group_8_element" title="Group 8 element">8</a></li> <li><a href="/wiki/Group_9_element" title="Group 9 element">9</a></li> <li><a href="/wiki/Group_10_element" title="Group 10 element">10</a></li> <li><a href="/wiki/Group_11_element" title="Group 11 element">11</a></li> <li><a href="/wiki/Group_12_element" title="Group 12 element">12</a></li> <li><a href="/wiki/Boron_group" title="Boron group">13 (Triels)</a></li> <li><a href="/wiki/Carbon_group" title="Carbon group">14 (Tetrels)</a></li> <li><a href="/wiki/Pnictogen" title="Pnictogen">15 (Pnictogens)</a></li> <li><a href="/wiki/Chalcogen" title="Chalcogen">16 (Chalcogens)</a></li> <li><a href="/wiki/Halogen" title="Halogen">17 (Halogens)</a></li> <li><a href="/wiki/Noble_gas" title="Noble gas">18 (Noble gases)</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Period_(periodic_table)" title="Period (periodic table)">Periods</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Period_1_element" title="Period 1 element">1</a></li> <li><a href="/wiki/Period_2_element" title="Period 2 element">2</a></li> <li><a href="/wiki/Period_3_element" title="Period 3 element">3</a></li> <li><a href="/wiki/Period_4_element" title="Period 4 element">4</a></li> <li><a href="/wiki/Period_5_element" title="Period 5 element">5</a></li> <li><a href="/wiki/Period_6_element" title="Period 6 element">6</a></li> <li><a href="/wiki/Period_7_element" title="Period 7 element">7</a></li> <li><a href="/wiki/Extended_periodic_table" title="Extended periodic table">8+</a> <ul><li><a href="/wiki/Extended_periodic_table#Aufbau_model" title="Extended periodic table">Aufbau</a></li> <li><a href="/wiki/Extended_periodic_table#Fricke" title="Extended periodic table">Fricke</a></li> <li><a href="/wiki/Extended_periodic_table#Pyykkö" title="Extended periodic table">Pyykkö</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Block_(periodic_table)" title="Block (periodic table)">Blocks</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Aufbau_principle" title="Aufbau principle">Aufbau principle</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;white-space: normal !important;">By <a href="/wiki/Properties_of_metals,_metalloids_and_nonmetals" title="Properties of metals, metalloids and nonmetals">metallicity</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Metal" title="Metal">Metals</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Lanthanide" title="Lanthanide">Lanthanides</a></li> <li><a href="/wiki/Actinide" title="Actinide">Actinides</a></li> <li><a href="/wiki/Transition_metal" title="Transition metal">Transition metals</a></li> <li><a href="/wiki/Post-transition_metal" title="Post-transition metal">Post-transition metals</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Metalloid" title="Metalloid">Metalloids</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Lists_of_metalloids" title="Lists of metalloids">Lists of metalloids by source</a></li> <li><a href="/wiki/Dividing_line_between_metals_and_nonmetals" title="Dividing line between metals and nonmetals">Dividing line</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Nonmetal" title="Nonmetal">Nonmetals</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Noble_gas" title="Noble gas">Noble gases</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;white-space: normal !important;">Other sets</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Platinum_group" title="Platinum group">Platinum-group metals (PGM)</a></li> <li><a href="/wiki/Rare-earth_element" title="Rare-earth element">Rare-earth elements</a></li> <li><a href="/wiki/Refractory_metals" title="Refractory metals">Refractory metals</a></li> <li><a href="/wiki/Precious_metal" title="Precious metal">Precious metals</a></li> <li><a href="/wiki/Coinage_metals" title="Coinage metals">Coinage metals</a></li> <li><a href="/wiki/Noble_metal" title="Noble metal">Noble metals</a></li> <li><a href="/wiki/Heavy_metal_element" title="Heavy metal element">Heavy metals</a></li> <li><a href="/wiki/Native_metal" title="Native metal">Native metals</a></li> <li><a href="/wiki/Transuranium_element" title="Transuranium element">Transuranium elements</a></li> <li><a href="/wiki/Superheavy_element" title="Superheavy element">Superheavy elements</a></li> <li><a href="/wiki/Major_actinide" title="Major actinide">Major actinides</a></li> <li><a href="/wiki/Minor_actinide" title="Minor actinide">Minor actinides</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group wraplinks" style="width:1%;white-space: normal !important;"><a href="/wiki/Chemical_element" title="Chemical element">Elements</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%;white-space: normal;"><a href="/wiki/List_of_chemical_elements" title="List of chemical elements">Lists</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li>By: <a href="/wiki/Abundance_of_the_chemical_elements" title="Abundance of the chemical elements">Abundance</a> (<a href="/wiki/Composition_of_the_human_body" title="Composition of the human body">in humans</a>)</li> <li><a href="/wiki/List_of_elements_by_atomic_properties" title="List of elements by atomic properties">Atomic properties</a></li> <li><a href="/wiki/List_of_elements_by_stability_of_isotopes" title="List of elements by stability of isotopes">Nuclear stability</a></li> <li><a href="/wiki/Chemical_symbol" title="Chemical symbol">Symbol</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;white-space: normal;"><a href="/wiki/Chemical_element#Properties" title="Chemical element">Properties</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/List_of_aqueous_ions_by_element" title="List of aqueous ions by element">Aqueous chemistry</a></li> <li><a href="/wiki/Periodic_table_(crystal_structure)" title="Periodic table (crystal structure)">Crystal structure</a></li> <li><a href="/wiki/Periodic_table_(electron_configurations)" title="Periodic table (electron configurations)">Electron configuration</a></li> <li><a href="/wiki/Electronegativity" title="Electronegativity">Electronegativity</a></li> <li><a href="/wiki/Goldschmidt_classification" title="Goldschmidt classification">Goldschmidt classification</a></li> <li><a href="/wiki/Term_symbol" title="Term symbol">Term symbol</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;white-space: normal;">Data pages</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Abundances_of_the_elements_(data_page)" title="Abundances of the elements (data page)">Abundance</a></li> <li><a href="/wiki/Atomic_radii_of_the_elements_(data_page)" title="Atomic radii of the elements (data page)">Atomic radius</a></li> <li><a href="/wiki/Boiling_points_of_the_elements_(data_page)" title="Boiling points of the elements (data page)">Boiling point</a></li> <li><a href="/wiki/Critical_points_of_the_elements_(data_page)" title="Critical points of the elements (data page)">Critical point</a></li> <li><a href="/wiki/Densities_of_the_elements_(data_page)" title="Densities of the elements (data page)">Density</a></li> <li><a href="/wiki/Elastic_properties_of_the_elements_(data_page)" title="Elastic properties of the elements (data page)">Elasticity</a></li> <li><a href="/wiki/Electrical_resistivities_of_the_elements_(data_page)" title="Electrical resistivities of the elements (data page)">Electrical resistivity</a></li> <li><a href="/wiki/Electron_affinity_(data_page)" title="Electron affinity (data page)">Electron affinity</a></li> <li><a href="/wiki/Electron_configurations_of_the_elements_(data_page)" title="Electron configurations of the elements (data page)">Electron configuration</a></li> <li><a href="/wiki/Electronegativities_of_the_elements_(data_page)" title="Electronegativities of the elements (data page)">Electronegativity</a></li> <li><a href="/wiki/Hardnesses_of_the_elements_(data_page)" title="Hardnesses of the elements (data page)">Hardness</a></li> <li><a href="/wiki/Heat_capacities_of_the_elements_(data_page)" title="Heat capacities of the elements (data page)">Heat capacity</a></li> <li><a href="/wiki/Heats_of_fusion_of_the_elements_(data_page)" title="Heats of fusion of the elements (data page)">Heat of fusion</a></li> <li><a href="/wiki/Heats_of_vaporization_of_the_elements_(data_page)" title="Heats of vaporization of the elements (data page)">Heat of vaporization</a></li> <li><a href="/wiki/Ionization_energies_of_the_elements_(data_page)" title="Ionization energies of the elements (data page)">Ionization energy</a></li> <li><a href="/wiki/Melting_points_of_the_elements_(data_page)" title="Melting points of the elements (data page)">Melting point</a></li> <li><a href="/wiki/Oxidation_state" title="Oxidation state">Oxidation state</a></li> <li><a href="/wiki/Speeds_of_sound_of_the_elements" title="Speeds of sound of the elements">Speed of sound</a></li> <li><a href="/wiki/Thermal_conductivities_of_the_elements_(data_page)" title="Thermal conductivities of the elements (data page)">Thermal conductivity</a></li> <li><a href="/wiki/Thermal_expansivities_of_the_elements" title="Thermal expansivities of the elements">Thermal expansion coefficient</a></li> <li><a href="/wiki/Vapor_pressures_of_the_elements_(data_page)" title="Vapor pressures of the elements (data page)">Vapor pressure</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group wraplinks" style="width:1%;white-space: normal !important;"><a href="/wiki/History_of_the_periodic_table" title="History of the periodic table">History</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Discovery_of_chemical_elements" title="Discovery of chemical elements">Element discoveries</a> <ul><li><a href="/wiki/Dmitri_Mendeleev" title="Dmitri Mendeleev">Dmitri Mendeleev</a></li> <li><a href="/wiki/Dmitri_Mendeleev#Periodic_table" title="Dmitri Mendeleev">1871 table</a></li> <li><a href="/wiki/Mendeleev%27s_predicted_elements" title="Mendeleev's predicted elements">1869 predictions</a></li></ul></li> <li><a href="/wiki/Naming_of_chemical_elements" title="Naming of chemical elements">Naming</a> <ul><li><a href="/wiki/List_of_chemical_element_name_etymologies" title="List of chemical element name etymologies">etymology</a></li> <li><a href="/wiki/List_of_chemical_element_naming_controversies" title="List of chemical element naming controversies">controversies</a></li> <li><a href="/wiki/List_of_chemical_elements_named_after_places" title="List of chemical elements named after places">for places</a></li> <li><a href="/wiki/List_of_chemical_elements_named_after_people" title="List of chemical elements named after people">for people</a></li> <li><a href="/wiki/Chemical_elements_in_East_Asian_languages" title="Chemical elements in East Asian languages">in East Asian languages</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group wraplinks" style="width:1%;white-space: normal !important;">See also</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/International_Union_of_Pure_and_Applied_Chemistry" title="International Union of Pure and Applied Chemistry">IUPAC</a> <ul><li><a href="/wiki/Chemical_nomenclature" title="Chemical nomenclature">nomenclature</a></li> <li><a href="/wiki/Systematic_element_name" title="Systematic element name">systematic element name</a></li></ul></li> <li><a href="/wiki/Trivial_name" title="Trivial name">Trivial name</a></li> <li><a href="/wiki/Dmitri_Mendeleev" title="Dmitri Mendeleev">Dmitri Mendeleev</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div> <ul><li><b><span class="noviewer" typeof="mw:File"><span title="Category"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/16px-Symbol_category_class.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/23px-Symbol_category_class.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/31px-Symbol_category_class.svg.png 2x" data-file-width="180" data-file-height="185" /></span></span> <a href="/wiki/Category:Periodic_table" title="Category:Periodic table">Category</a></b></li> <li><b><span class="noviewer" typeof="mw:File"><span title="WikiProject"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/3/37/People_icon.svg/16px-People_icon.svg.png" decoding="async" width="16" height="16" class="mw-file-element" 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href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Branches_of_chemistry" title="Template:Branches of chemistry"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Branches_of_chemistry" title="Template talk:Branches of chemistry"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Branches_of_chemistry" title="Special:EditPage/Template:Branches of chemistry"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Branches_of_chemistry" style="font-size:114%;margin:0 4em">Branches of <a href="/wiki/Chemistry" title="Chemistry">chemistry</a></div></th></tr><tr><td class="navbox-abovebelow" colspan="2"><div> <ul><li><a href="/wiki/Glossary_of_chemical_formulae" title="Glossary of chemical formulae">Glossary of chemical formulae</a></li> <li><a href="/wiki/List_of_biomolecules" title="List of biomolecules">List of biomolecules</a></li> <li><a href="/wiki/List_of_inorganic_compounds" title="List of inorganic compounds">List of inorganic compounds</a></li> <li><a class="mw-selflink selflink">Periodic table</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Analytical_chemistry" title="Analytical chemistry">Analytical</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Instrumental_chemistry" title="Instrumental chemistry">Instrumental chemistry</a></li> <li><a href="/wiki/Electroanalytical_methods" title="Electroanalytical methods">Electroanalytical methods</a></li> <li><a href="/wiki/Spectroscopy" title="Spectroscopy">Spectroscopy</a> <ul><li><a href="/wiki/Infrared_spectroscopy" title="Infrared spectroscopy">IR</a></li> <li><a href="/wiki/Raman_spectroscopy" title="Raman spectroscopy">Raman</a></li> <li><a href="/wiki/Ultraviolet%E2%80%93visible_spectroscopy" title="Ultraviolet–visible spectroscopy">UV-Vis</a></li> <li><a href="/wiki/Nuclear_magnetic_resonance_spectroscopy" title="Nuclear magnetic resonance spectroscopy">NMR</a></li></ul></li> <li><a href="/wiki/Mass_spectrometry" title="Mass spectrometry">Mass spectrometry</a> <ul><li><a href="/wiki/Electron_ionization" title="Electron ionization">EI</a></li> <li><a href="/wiki/Inductively_coupled_plasma_mass_spectrometry" title="Inductively coupled plasma mass spectrometry">ICP</a></li> <li><a href="/wiki/Matrix-assisted_laser_desorption/ionization" title="Matrix-assisted laser desorption/ionization">MALDI</a></li></ul></li> <li><a href="/wiki/Separation_process" title="Separation process">Separation process</a></li> <li><a href="/wiki/Chromatography" title="Chromatography">Chromatography</a> <ul><li><a href="/wiki/Gas_chromatography" title="Gas chromatography">GC</a></li> <li><a href="/wiki/High-performance_liquid_chromatography" title="High-performance liquid chromatography">HPLC</a></li></ul></li> <li><a href="/wiki/Crystallography" title="Crystallography">Crystallography</a></li> <li><a href="/wiki/Characterization_(materials_science)" title="Characterization (materials science)">Characterization</a></li> <li><a href="/wiki/Titration" title="Titration">Titration</a></li> <li><a href="/wiki/Wet_chemistry" title="Wet chemistry">Wet chemistry</a></li> <li><a href="/wiki/Calorimetry" title="Calorimetry">Calorimetry</a></li> <li><a href="/wiki/Elemental_analysis" title="Elemental analysis">Elemental analysis</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Theoretical_chemistry" title="Theoretical chemistry">Theoretical</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a 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style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Electrochemistry" title="Electrochemistry">Electrochemistry</a> <ul><li><a href="/wiki/Spectroelectrochemistry" title="Spectroelectrochemistry">Spectroelectrochemistry</a></li> <li><a href="/wiki/Photoelectrochemistry" title="Photoelectrochemistry">Photoelectrochemistry</a></li></ul></li> <li><a href="/wiki/Thermochemistry" title="Thermochemistry">Thermochemistry</a></li> <li><a href="/wiki/Chemical_thermodynamics" title="Chemical thermodynamics">Chemical thermodynamics</a></li> <li><a href="/wiki/Surface_science" title="Surface science">Surface science</a></li> <li><a href="/wiki/Interface_and_colloid_science" title="Interface and colloid science">Interface and colloid science</a> <ul><li><a href="/wiki/Micromeritics" title="Micromeritics">Micromeritics</a></li></ul></li> <li><a href="/wiki/Cryochemistry" title="Cryochemistry">Cryochemistry</a></li> <li><a href="/wiki/Sonochemistry" title="Sonochemistry">Sonochemistry</a></li> <li><a href="/wiki/Structural_chemistry" title="Structural chemistry">Structural chemistry</a></li> <li><a href="/wiki/Chemical_physics" title="Chemical physics">Chemical physics</a> <ul><li><a href="/wiki/Molecular_physics" title="Molecular physics">Molecular physics</a></li></ul></li> <li><a href="/wiki/Femtochemistry" title="Femtochemistry">Femtochemistry</a></li> <li><a href="/wiki/Chemical_kinetics" title="Chemical kinetics">Chemical kinetics</a></li> <li><a href="/wiki/Spectroscopy" title="Spectroscopy">Spectroscopy</a></li> <li><a href="/wiki/Photochemistry" title="Photochemistry">Photochemistry</a></li> <li><a href="/wiki/Spin_chemistry" title="Spin chemistry">Spin chemistry</a></li> <li><a href="/wiki/Microwave_chemistry" title="Microwave chemistry">Microwave chemistry</a></li> <li><a href="/wiki/Equilibrium_chemistry" title="Equilibrium chemistry">Equilibrium chemistry</a></li> <li><a href="/wiki/Mechanochemistry" title="Mechanochemistry">Mechanochemistry</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Inorganic_chemistry" title="Inorganic chemistry">Inorganic</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Coordination_complex" title="Coordination complex">Coordination chemistry</a></li> <li><a href="/wiki/Magnetochemistry" title="Magnetochemistry">Magnetochemistry</a></li> <li><a href="/wiki/Organometallic_chemistry" title="Organometallic chemistry">Organometallic chemistry</a> <ul><li><a href="/wiki/Organolanthanide_chemistry" title="Organolanthanide chemistry">Organolanthanide chemistry</a></li></ul></li> <li><a href="/wiki/Atom_cluster" class="mw-redirect" title="Atom cluster">Cluster chemistry</a></li> <li><a href="/wiki/Solid-state_chemistry" title="Solid-state chemistry">Solid-state chemistry</a></li> <li><a href="/wiki/Ceramic_chemistry" class="mw-redirect" title="Ceramic chemistry">Ceramic chemistry</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Organic_chemistry" title="Organic chemistry">Organic</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Stereochemistry" title="Stereochemistry">Stereochemistry</a> <ul><li><a href="/wiki/Alkane_stereochemistry" class="mw-redirect" title="Alkane stereochemistry">Alkane stereochemistry</a></li></ul></li> <li><a href="/wiki/Physical_organic_chemistry" title="Physical organic chemistry">Physical organic chemistry</a></li> <li><a href="/wiki/Organic_reactions" class="mw-redirect" title="Organic reactions">Organic reactions</a></li> <li><a href="/wiki/Organic_synthesis" title="Organic synthesis">Organic synthesis</a></li> <li><a href="/wiki/Retrosynthetic_analysis" title="Retrosynthetic analysis">Retrosynthetic analysis</a></li> <li><a href="/wiki/Enantioselective_synthesis" title="Enantioselective synthesis">Enantioselective synthesis</a></li> <li><a href="/wiki/Total_synthesis" title="Total synthesis">Total synthesis</a> / <a href="/wiki/Semisynthesis" title="Semisynthesis">Semisynthesis</a></li> <li><a href="/wiki/Fullerene_chemistry" title="Fullerene chemistry">Fullerene chemistry</a></li> <li><a href="/wiki/Polymer_chemistry" title="Polymer chemistry">Polymer chemistry</a></li> <li><a href="/wiki/Petrochemistry" class="mw-redirect" title="Petrochemistry">Petrochemistry</a></li> <li><a href="/wiki/Dynamic_covalent_chemistry" title="Dynamic covalent chemistry">Dynamic covalent chemistry</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Biochemistry" title="Biochemistry">Biological</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Biochemistry" title="Biochemistry">Biochemistry</a> <ul><li><a href="/wiki/Molecular_biology" title="Molecular biology">Molecular biology</a></li> <li><a href="/wiki/Cell_biology" title="Cell biology">Cell biology</a></li></ul></li> <li><a href="/wiki/Chemical_biology" title="Chemical biology">Chemical biology</a> <ul><li><a href="/wiki/Bioorthogonal_chemistry" title="Bioorthogonal chemistry">Bioorthogonal chemistry</a></li></ul></li> <li><a href="/wiki/Medicinal_chemistry" title="Medicinal chemistry">Medicinal chemistry</a> <ul><li><a href="/wiki/Pharmacology" title="Pharmacology">Pharmacology</a></li></ul></li> <li><a href="/wiki/Clinical_chemistry" title="Clinical chemistry">Clinical chemistry</a></li> <li><a href="/wiki/Neurochemistry" title="Neurochemistry">Neurochemistry</a></li> <li><a href="/wiki/Bioorganic_chemistry" title="Bioorganic chemistry">Bioorganic chemistry</a></li> <li><a href="/wiki/Bioorganometallic_chemistry" title="Bioorganometallic chemistry">Bioorganometallic chemistry</a></li> <li><a href="/wiki/Bioinorganic_chemistry" title="Bioinorganic chemistry">Bioinorganic chemistry</a></li> <li><a href="/wiki/Biophysical_chemistry" title="Biophysical chemistry">Biophysical chemistry</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Interdisciplinarity" title="Interdisciplinarity">Interdisciplinarity</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Nuclear_chemistry" title="Nuclear chemistry">Nuclear chemistry</a> <ul><li><a href="/wiki/Radiochemistry" title="Radiochemistry">Radiochemistry</a></li> <li><a href="/wiki/Radiation_chemistry" title="Radiation chemistry">Radiation chemistry</a></li> <li><a href="/wiki/Actinide_chemistry" title="Actinide chemistry">Actinide chemistry</a></li></ul></li> <li><a href="/wiki/Cosmochemistry" title="Cosmochemistry">Cosmochemistry</a> / <a href="/wiki/Astrochemistry" title="Astrochemistry">Astrochemistry</a> / <a href="/wiki/Stellar_chemistry" title="Stellar chemistry">Stellar chemistry</a></li> <li><a href="/wiki/Geochemistry" title="Geochemistry">Geochemistry</a> <ul><li><a href="/wiki/Biogeochemistry" title="Biogeochemistry">Biogeochemistry</a></li> <li><a href="/wiki/Photogeochemistry" title="Photogeochemistry">Photogeochemistry</a></li></ul></li></ul> <ul><li><a href="/wiki/Environmental_chemistry" title="Environmental chemistry">Environmental chemistry</a> <ul><li><a href="/wiki/Atmospheric_chemistry" title="Atmospheric chemistry">Atmospheric chemistry</a></li> <li><a href="/wiki/Ocean_chemistry" class="mw-redirect" title="Ocean chemistry">Ocean chemistry</a></li></ul></li> <li><a href="/wiki/Clay_chemistry" title="Clay chemistry">Clay chemistry</a></li> <li><a href="/wiki/Carbochemistry" title="Carbochemistry">Carbochemistry</a></li> <li><a href="/wiki/Food_chemistry" title="Food chemistry">Food chemistry</a> <ul><li><a href="/wiki/Carbohydrate_chemistry" class="mw-redirect" title="Carbohydrate chemistry">Carbohydrate chemistry</a></li> <li><a href="/wiki/Food_physical_chemistry" title="Food physical chemistry">Food physical chemistry</a></li></ul></li> <li><a href="/wiki/Agricultural_chemistry" title="Agricultural chemistry">Agricultural chemistry</a> <ul><li><a href="/wiki/Soil_chemistry" title="Soil chemistry">Soil chemistry</a></li></ul></li></ul> <ul><li><a href="/wiki/Chemistry_education" title="Chemistry education">Chemistry education</a> <ul><li><a href="/wiki/Amateur_chemistry" title="Amateur chemistry">Amateur chemistry</a></li> <li><a href="/wiki/General_chemistry" title="General chemistry">General chemistry</a></li></ul></li> <li><a href="/wiki/Clandestine_chemistry" title="Clandestine chemistry">Clandestine chemistry</a></li> <li><a href="/wiki/Forensic_chemistry" title="Forensic chemistry">Forensic chemistry</a> <ul><li><a href="/wiki/Forensic_toxicology" title="Forensic toxicology">Forensic toxicology</a></li> <li><a href="/wiki/Post-mortem_chemistry" title="Post-mortem chemistry">Post-mortem chemistry</a></li></ul></li></ul> <ul><li><a href="/wiki/Nanochemistry" title="Nanochemistry">Nanochemistry</a> <ul><li><a href="/wiki/Supramolecular_chemistry" title="Supramolecular chemistry">Supramolecular chemistry</a></li></ul></li> <li><a href="/wiki/Chemical_synthesis" title="Chemical synthesis">Chemical synthesis</a> <ul><li><a href="/wiki/Green_chemistry" title="Green chemistry">Green chemistry</a></li> <li><a href="/wiki/Click_chemistry" title="Click chemistry">Click chemistry</a></li> <li><a href="/wiki/Combinatorial_chemistry" title="Combinatorial chemistry">Combinatorial chemistry</a></li> <li><a href="/wiki/Biosynthesis" title="Biosynthesis">Biosynthesis</a></li></ul></li> <li><a href="/wiki/Chemical_engineering" title="Chemical engineering">Chemical engineering</a> <ul><li><a href="/wiki/Stoichiometry" title="Stoichiometry">Stoichiometry</a></li></ul></li> <li><a href="/wiki/Materials_science" title="Materials science">Materials science</a> <ul><li><a href="/wiki/Metallurgy" title="Metallurgy">Metallurgy</a></li> <li><a href="/wiki/Ceramic_engineering" title="Ceramic engineering">Ceramic engineering</a></li> <li><a href="/wiki/Polymer_science" title="Polymer science">Polymer science</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">See also</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/History_of_chemistry" title="History of chemistry">History of chemistry</a></li> <li><a href="/wiki/Nobel_Prize_in_Chemistry" title="Nobel Prize in Chemistry">Nobel Prize in Chemistry</a></li> <li><a href="/wiki/Timeline_of_chemistry" title="Timeline of chemistry">Timeline of chemistry</a> <ul><li><a href="/wiki/Discovery_of_chemical_elements" title="Discovery of chemical elements">of element discoveries</a></li></ul></li> <li>"<a href="/wiki/The_central_science" title="The central science">The central science</a>"</li> <li><a href="/wiki/Chemical_reaction" title="Chemical reaction">Chemical reaction</a> <ul><li><a href="/wiki/Catalysis" title="Catalysis">Catalysis</a></li></ul></li> <li><a href="/wiki/Chemical_element" title="Chemical element">Chemical element</a></li> <li><a href="/wiki/Chemical_compound" title="Chemical compound">Chemical compound</a></li> <li><a href="/wiki/Atom" title="Atom">Atom</a></li> <li><a href="/wiki/Molecule" title="Molecule">Molecule</a></li> <li><a href="/wiki/Ion" title="Ion">Ion</a></li> <li><a href="/wiki/Chemical_substance" title="Chemical substance">Chemical substance</a></li> <li><a href="/wiki/Chemical_bond" title="Chemical bond">Chemical bond</a></li> <li><a href="/wiki/Alchemy" title="Alchemy">Alchemy</a></li> <li><a href="/wiki/Quantum_mechanics" title="Quantum mechanics">Quantum mechanics</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div> <ul><li><span class="noviewer" typeof="mw:File"><span title="Category"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/16px-Symbol_category_class.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/23px-Symbol_category_class.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/31px-Symbol_category_class.svg.png 2x" data-file-width="180" data-file-height="185" /></span></span> <b><a href="/wiki/Category:Chemistry" title="Category:Chemistry">Category</a></b></li> <li><span class="noviewer" typeof="mw:File"><span title="Commons page"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/12px-Commons-logo.svg.png" decoding="async" width="12" height="16" class="mw-file-element" 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class="mw-valign-text-top noprint" typeof="mw:File/Frameless"><a href="https://www.wikidata.org/wiki/Q10693#identifiers" title="Edit this at Wikidata"><img alt="Edit this at Wikidata" src="//upload.wikimedia.org/wikipedia/en/thumb/8/8a/OOjs_UI_icon_edit-ltr-progressive.svg/10px-OOjs_UI_icon_edit-ltr-progressive.svg.png" decoding="async" width="10" height="10" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/8/8a/OOjs_UI_icon_edit-ltr-progressive.svg/15px-OOjs_UI_icon_edit-ltr-progressive.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/8/8a/OOjs_UI_icon_edit-ltr-progressive.svg/20px-OOjs_UI_icon_edit-ltr-progressive.svg.png 2x" data-file-width="20" data-file-height="20" /></a></span></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">International</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"><ul><li><span class="uid"><a rel="nofollow" class="external text" href="https://viaf.org/viaf/186605590">VIAF</a></span><ul><li><span class="uid"><a rel="nofollow" class="external text" href="https://viaf.org/viaf/184014738">2</a></span></li></ul></li></ul></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">National</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"><ul><li><span class="uid"><a rel="nofollow" class="external text" href="https://d-nb.info/gnd/4125872-1">Germany</a></span></li><li><span class="uid"><a rel="nofollow" class="external text" href="https://id.loc.gov/authorities/sh85099885">United States</a></span><ul><li><span class="uid"><a rel="nofollow" class="external text" href="https://id.loc.gov/authorities/no2010151385">2</a></span></li><li><span class="uid"><a rel="nofollow" class="external text" href="https://id.loc.gov/authorities/n2002011571">3</a></span></li><li><span class="uid"><a rel="nofollow" class="external text" href="https://id.loc.gov/authorities/sh2014000656">4</a></span></li></ul></li><li><span class="uid"><a rel="nofollow" class="external text" href="https://catalogue.bnf.fr/ark:/12148/cb122746941">France</a></span></li><li><span class="uid"><a rel="nofollow" class="external text" href="https://data.bnf.fr/ark:/12148/cb122746941">BnF data</a></span></li><li><span class="uid"><span class="rt-commentedText tooltip tooltip-dotted" title="periodická soustava prvků"><a rel="nofollow" class="external text" href="https://aleph.nkp.cz/F/?func=find-c&local_base=aut&ccl_term=ica=ph124041&CON_LNG=ENG">Czech Republic</a></span></span></li><li><span class="uid"><a rel="nofollow" class="external text" href="http://catalogo.bne.es/uhtbin/authoritybrowse.cgi?action=display&authority_id=XX532419">Spain</a></span></li><li><span class="uid"><a rel="nofollow" class="external text" href="http://olduli.nli.org.il/F/?func=find-b&local_base=NLX10&find_code=UID&request=987007364980405171">Israel</a></span></li></ul></div></td></tr></tbody></table></div> <!-- NewPP limit report Parsed by mw‐web.codfw.main‐f69cdc8f6‐d7pw2 Cached time: 20241122221034 Cache expiry: 2592000 Reduced expiry: false Complications: [vary‐revision‐sha1, show‐toc] CPU time usage: 5.367 seconds Real time usage: 5.701 seconds Preprocessor visited node count: 152095/1000000 Post‐expand include size: 1535950/2097152 bytes Template argument size: 86065/2097152 bytes Highest expansion depth: 18/100 Expensive parser function count: 19/500 Unstrip recursion depth: 1/20 Unstrip post‐expand size: 1125940/5000000 bytes Lua time usage: 2.542/10.000 seconds Lua memory usage: 11451230/52428800 bytes Lua Profile: recursiveClone <mwInit.lua:45> 680 ms 25.0% MediaWiki\Extension\Scribunto\Engines\LuaSandbox\LuaSandboxCallback::callParserFunction 280 ms 10.3% ? 280 ms 10.3% 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