Isotope | Examples & Definition

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right-0" > <em class="material-icons font-26" data-icon="close"></em> </button> </div> <div class="section-content pl-10 pr-20 pl-sm-50 pr-sm-60 pl-lg-5 pr-lg-10 pt-10 pt-lg-0 bg-gray-50 clear-catfish-ad"> <div class="toc mb-20"> <div class="font-serif font-14 font-weight-bold mx-15 mb-15 mt-20"> Table of Contents </div> <ul class="list-unstyled my-0" data-level="h1"><li data-target="#ref1"><div class="pl-25"><a class="link-gray-900 w-100" href="/science/isotope">Introduction & Top Questions</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref48249"><div class="d-flex align-items-center"><div class="ml-25"></div><a class="w-100 link-gray-900" href="/science/isotope/The-discovery-of-isotopes">The discovery of isotopes</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref48250"><div class="d-flex align-items-center"><div class="ml-25"></div><a class="w-100 link-gray-900" href="/science/isotope/The-discovery-of-isotopes#ref48250">Nuclear stability</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref48251"><div class="d-flex align-items-center"><div class="ml-25"></div><a class="w-100 link-gray-900" href="/science/isotope/The-discovery-of-isotopes#ref48251">Radioactive isotopes</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref48252"><div class="d-flex align-items-center"><div class="ml-25"></div><a class="w-100 link-gray-900" href="/science/isotope/Elemental-and-isotopic-abundances">Elemental and isotopic abundances</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref48253"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/science/isotope/Variations-in-isotopic-abundances">Variations in isotopic abundances</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref48254"><a class="w-100 link-gray-900" href="/science/isotope/Variations-in-isotopic-abundances#ref48254">Radioactive decay</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref48255"><a class="w-100 link-gray-900" href="/science/isotope/Variations-in-isotopic-abundances#ref48255">Mass fractionation</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref48256"><a class="w-100 link-gray-900" href="/science/isotope/Variations-in-isotopic-abundances#ref48256">Other causes of isotopic abundance variations</a></li></ul></div></li><li data-target="#ref48257"><div class="d-flex align-items-center"><div class="ml-25"></div><a class="w-100 link-gray-900" href="/science/isotope/Variations-in-isotopic-abundances#ref48257">Physical properties associated with isotopes</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref48258"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/science/isotope/Variations-in-isotopic-abundances#ref48258">Effect of isotopes on atomic and molecular spectra</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref48259"><a class="w-100 link-gray-900" href="/science/isotope/Molecular-vibrations">Molecular vibrations</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref48260"><a class="w-100 link-gray-900" href="/science/isotope/Molecular-vibrations#ref48260">Importance in the study of polyatomic molecules</a></li></ul></div></li><li data-target="#ref48261"><div class="d-flex align-items-center"><div class="ml-25"></div><a class="w-100 link-gray-900" href="/science/isotope/Molecular-vibrations#ref48261">Chemical effects of isotopic substitution</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref48262"><div class="d-flex align-items-center"><div class="ml-25"></div><a class="w-100 link-gray-900" href="/science/isotope/Molecular-vibrations#ref48262">Effect of isotopic substitution on reaction rates</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref48263"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/science/isotope/Isotope-separation-and-enrichment">Isotope separation and enrichment</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref48264"><a class="w-100 link-gray-900" href="/science/isotope/Isotope-separation-and-enrichment#ref48264">Mass spectrometry</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref48265"><a class="w-100 link-gray-900" href="/science/isotope/Isotope-separation-and-enrichment#ref48265">Distillation</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref48266"><a class="w-100 link-gray-900" href="/science/isotope/Isotope-separation-and-enrichment#ref48266">Chemical exchange reactions</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref48267"><a class="w-100 link-gray-900" href="/science/isotope/Isotope-separation-and-enrichment#ref48267">Gaseous diffusion</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref48268"><a class="w-100 link-gray-900" href="/science/isotope/Isotope-separation-and-enrichment#ref48268">Gas centrifugation</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref48269"><a class="w-100 link-gray-900" href="/science/isotope/Isotope-separation-and-enrichment#ref48269">Photochemical enrichment methods</a></li></ul></div></li></ul> <a class="toc-extra-link link-gray-900" href="https://www.britannica.com/science/isotope/additional-info">References & Edit History</a> <a class="toc-extra-link link-gray-900" href="/facts/isotope">Related Topics</a> </div> <div class="tlr-media-slider pb-10 mb-30"> <a class="section-header link-gray-900 font-serif font-14 font-weight-bold mb-10 mx-10" href="https://www.britannica.com/science/isotope/images-videos">Images & Videos</a> <div class="slider js-slider position-relative d-inline-flex align-items-center mw-100 "> <div class="slider-container js-slider-container overflow-hidden d-flex overflow-hidden text-nowrap ml-15"> <a href="/video/What-are-isotopes/246891" data-href="/media/1/296583/246891" class="media-overlay-link d-inline-block mr-5"> <div 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They write new content and verify and edit content received from contributors.</div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link font-12 "> The Editors of Encyclopaedia Britannica</span></div> <div class="last-updated font-12 font-serif"> <span class="text-gray-700"> Last Updated: <time datetime="2024-11-21T00:00:00CST" >Nov 21, 2024</time> •</span> <a class="byline-edit-history" href="https://www.britannica.com/science/isotope/additional-info#history" rel="nofollow">Article History</a> </div></div> </div> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button d-none d-sm-block js-sections-inline-button module-spacing btn d-lg-none"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <div class="d-flex d-sm-none flex-row"> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button js-sections-inline-button module-spacing"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <button class="ai-ask-button btn border-2 ai-ask-button btn border-2 module-spacing btn-sm js-inline-ai-ask-button btn-outline-red-400 border-red-400 p-10 ml-5"> Ask the Chatbot a Question </button> </div> <div class="js-qf-module qf-module px-40 px-sm-20 py-15 mx-auto module-spacing font-14 bg-gray-50 rounded"> <div class="facts-list mt-10"> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Key People: </dt> <dd><a href="/biography/Francis-William-Aston" topicid="39838">Francis William Aston</a></dd> <dd><a href="/biography/Frederick-Soddy" topicid="552022">Frederick Soddy</a></dd> <dd><a href="/biography/Theodore-William-Richards" topicid="502620">Theodore William Richards</a></dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> </div> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Related Topics: </dt> <dd><a href="/science/deuterium" topicid="159684">deuterium</a></dd> <dd><a href="/science/radioactive-isotope" topicid="489027">radioactive isotope</a></dd> <dd><a href="/science/tritium" topicid="606002">tritium</a></dd> <dd><a href="/science/tantalum-180" topicid="2152679">tantalum-180</a></dd> <dd><a href="/science/tantalum-181" topicid="2152678">tantalum-181</a></dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> </div> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>On the Web: </dt> <dd><a href="https://isotopes.gov/isotope-basics" target="_blank">National Isotope Development Center - Isotope Basics</a> (Nov. 21, 2024)</dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> <div class="text-center"> <a class="btn btn-sm btn-link p-0" href="/facts/isotope"> See all related content </a> </div> </div> </div> </div><script type="application/ld+json"> { "@context": "https://schema.org", "@type": "FAQPage", "mainEntity": [ { "@type" : "Question", "name" : "<div>What is an isotope?<\/div><em><\/em>", "acceptedAnswer" : { "@type" : "Answer", "text" : "An isotope is one of two or more species of atoms of a chemical element with the same atomic number and position in the periodic table and nearly identical chemical behavior but with different atomic masses and physical properties. Every chemical element has one or more isotopes." } } , { "@type" : "Question", "name" : "<div>Why do isotopes have different properties?<\/div><em><\/em>", "acceptedAnswer" : { "@type" : "Answer", "text" : "Differences in the properties of isotopes can be attributed to either of two causes: differences in mass or differences in nuclear structure. Scientists usually refer to the former as isotope effects and to the latter by a variety of more specialized names." } } , { "@type" : "Question", "name" : "<div>When are isotopes stable?<\/div><em><\/em>", "acceptedAnswer" : { "@type" : "Answer", "text" : "Isotopes are said to be stable if, when left alone, they show no perceptible tendency to change spontaneously. A uniform scale of nuclear stability that applies to both stable and unstable isotopes alike is based on comparing measured isotope masses with the masses of their constituent electrons, protons, and neutrons." } } , { "@type" : "Question", "name" : "<div>How were isotopes discovered?<\/div><em><\/em>", "acceptedAnswer" : { "@type" : "Answer", "text" : "The existence of isotopes emerged from two independent lines of research, the first being the study of radioactivity. The unambiguous confirmation of isotopes in stable elements not associated directly with either uranium or thorium came with the development of the mass spectrograph." } } ] } </script> <div class="top-questions qa-accordion d-flex flex-column module-spacing"><div class="font-weight-bold font-14 mb-5"> Top Questions </div><div id="intent-accordion" class="md-intent-accordion"><div class="top-question bg-gray-50 rounded" data-value="1"><h3 class="accordion--question font-14 font-weight-normal cursor-pointer rounded"><div class="pe-none d-flex justify-content-between align-items-center"><div>What is an isotope?</div><em class="material-icons" data-icon="expand_more"></em></div></h3><div class="accordion--answer hidden p-15 pt-5 font-16 mb-5"><div class="accordion--answer-copy"><p>An isotope is one of two or more species of atoms of a chemical element with the same atomic number and position in the periodic table and nearly identical chemical behavior but with different atomic masses and physical properties. Every chemical element has one or more isotopes.</p></div></div></div><div class="top-question bg-gray-50 rounded" data-value="2"><h3 class="accordion--question font-14 font-weight-normal cursor-pointer rounded"><div class="pe-none d-flex justify-content-between align-items-center"><div>Why do isotopes have different properties?</div><em class="material-icons" data-icon="expand_more"></em></div></h3><div class="accordion--answer hidden p-15 pt-5 font-16 mb-5"><div class="accordion--answer-copy"><p>Differences in the properties of isotopes can be attributed to either of two causes: differences in mass or differences in nuclear structure. Scientists usually refer to the former as isotope effects and to the latter by a variety of more specialized names.</p></div></div></div><div class="top-question bg-gray-50 rounded" data-value="3"><h3 class="accordion--question font-14 font-weight-normal cursor-pointer rounded"><div class="pe-none d-flex justify-content-between align-items-center"><div>When are isotopes stable?</div><em class="material-icons" data-icon="expand_more"></em></div></h3><div class="accordion--answer hidden p-15 pt-5 font-16 mb-5"><div class="accordion--answer-copy"><p>Isotopes are said to be stable if, when left alone, they show no perceptible tendency to change spontaneously. A uniform scale of nuclear stability that applies to both stable and unstable isotopes alike is based on comparing measured isotope masses with the masses of their constituent electrons, protons, and neutrons.</p></div></div></div><div class="top-question bg-gray-50 rounded" data-value="4"><h3 class="accordion--question font-14 font-weight-normal cursor-pointer rounded"><div class="pe-none d-flex justify-content-between align-items-center"><div>How were isotopes discovered?</div><em class="material-icons" data-icon="expand_more"></em></div></h3><div class="accordion--answer hidden p-15 pt-5 font-16 mb-5"><div class="accordion--answer-copy"><p>The existence of isotopes emerged from two independent lines of research, the first being the study of radioactivity. The unambiguous confirmation of isotopes in stable elements not associated directly with either uranium or thorium came with the development of the mass spectrograph.</p></div></div></div><button class="show-more-button js-toggle-top-questions btn btn-unstyled font-14 d-flex pr-10 rounded-sm"><em class="material-icons" data-icon="expand_more"></em></button></div></div><span class="marker before-article"></span><section data-level="1" id="ref1"><span class="marker PREMOD1 mod-inline"></span><div class="assemblies"><div class="w-100"><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="246891" data-asm-type="video"><div class="md-assembly-wrapper card-media " data-type="video" video-id="216564"><a data-id="216564" class="gtm-assembly-link d-flex justify-content-center" style="--aspect-ratio: 16/9" href="/video/What-are-isotopes/-246891"><img src="https://cdn.britannica.com/64/216564-138-51A467D7/What-are-isotopes.jpg?w=800&h=450&c=crop" alt="What are isotopes and how do they work?" loading="lazy"><script type="application/json"> { "sources": [ { "file" : "//content.jwplatform.com/manifests/Fuzt5yBl.m3u8" } ], "image": "https://cdn.britannica.com/64/216564-138-51A467D7/What-are-isotopes.jpg" ,"tracks": [ { "file" : "//assets-jpcust.jwpsrv.com/tracks/szXQf68B", "label": "English" } ] ,"adfile": "//content.jwplatform.com/manifests/3mvoqIf6.m3u8" } </script><div class="btn btn-xl btn-white btn-circle position-absolute shadow" style="top: 50%; transform: translateY(-50%)"><em class="material-icons" data-icon="play_arrow"></em></div></a></div><figcaption class="card-body"><div class="md-assembly-caption text-muted font-14 font-serif line-clamp"><span><span class="md-assembly-title font-weight-bold mr-5 d-inline font-sans-serif md-video-caption" video-control="216564">What are isotopes and how do they work?</span><span>An overview of isotopes.</span><button class="js-more-btn d-none btn btn-unstyled font-12 bg-white js-content" aria-label="Toggle more/less fact data"><span class="link-blue">(more)</span></button></span></div><a class="font-14 mt-10 d-inline-block" href="/science/isotope/images-videos">See all videos for this article</a></figcaption></figure></div></div><p class="topic-paragraph"><strong><span id="ref496298"></span>isotope</strong>, one of two or more species of <a href="https://www.britannica.com/science/atom" class="md-crosslink " data-show-preview="true">atoms</a> of a <a href="https://www.britannica.com/science/chemical-element" class="md-crosslink autoxref " data-show-preview="true">chemical element</a> with the same <a href="https://www.britannica.com/science/atomic-number" class="md-crosslink " data-show-preview="true">atomic number</a> and position in the <a href="https://www.britannica.com/science/periodic-table" class="md-crosslink " data-show-preview="true">periodic table</a> and nearly identical chemical behaviour but with different <a href="https://www.britannica.com/science/atomic-mass" class="md-crosslink " data-show-preview="true">atomic masses</a> and physical properties. Every chemical element has one or more isotopes.</p><span class="marker MOD1 mod-inline"></span><span class="marker PREMOD2 mod-inline"></span><p class="topic-paragraph">An <a href="https://www.britannica.com/science/atom" class="md-crosslink autoxref " data-show-preview="true">atom</a> is first identified and labeled according to the number of <a href="https://www.britannica.com/science/proton-subatomic-particle" class="md-crosslink " data-show-preview="true">protons</a> in its nucleus. This <span id="ref496299"></span><a href="https://www.britannica.com/science/atomic-number" class="md-crosslink " data-show-preview="true">atomic number</a> is ordinarily given the symbol <em>Z</em>. The great importance of the atomic number derives from the observation that all atoms with the same atomic number have nearly, if not precisely, identical chemical properties. A large collection of atoms with the same atomic number <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="constitutes" href="https://www.merriam-webster.com/dictionary/constitutes" data-type="MW">constitutes</a> a sample of an element. A bar of pure <a href="https://www.britannica.com/science/uranium" class="md-crosslink " data-show-preview="true">uranium</a>, for instance, would consist entirely of atoms with atomic number 92. The periodic table of the elements assigns one place to every atomic number, and each of these places is labeled with the common name of the element, as, for example, <a href="https://www.britannica.com/science/calcium" class="md-crosslink " data-show-preview="true">calcium</a>, <a href="https://www.britannica.com/science/radon" class="md-crosslink " data-show-preview="true">radon</a>, or uranium.<span class="inline-youtube-video d-print-none"><iframe class="" width="560" height="315" allow="autoplay; encrypted-media" frameborder="0" allowfullscreen="allowfullscreen" src="https://www.youtube-nocookie.com/embed/8_C5Au1pr6w?rel=0"></iframe></span></p><span class="marker MOD2 mod-inline"></span><span class="marker PREMOD3 mod-inline"></span><p class="topic-paragraph">Not all the atoms of an element need have the same number of <span id="ref496300"></span><a href="https://www.britannica.com/science/neutron" class="md-crosslink " data-show-preview="true">neutrons</a> in their nuclei. In fact, it is precisely the variation in the number of neutrons in the nuclei of atoms that gives rise to isotopes. <a href="https://www.britannica.com/science/hydrogen" class="md-crosslink " data-show-preview="true">Hydrogen</a> is a case in point. It has the atomic number 1. Three nuclei with one <a href="https://www.britannica.com/science/proton-subatomic-particle" class="md-crosslink autoxref " data-show-preview="true">proton</a> are known that contain 0, 1, and 2 neutrons, respectively. The three share the place in the periodic table assigned to atomic number 1 and hence are called isotopes (from the Greek <em>isos</em>, meaning “same,” and <em>topos</em>, signifying “place”) of hydrogen.</p><span class="marker MOD3 mod-inline"></span><span class="marker PREMOD4 mod-inline"></span><p class="topic-paragraph">Many important properties of an isotope depend on its mass. The total number of neutrons and protons (symbol <em>A</em>), or <span id="ref496301"></span><a href="https://www.britannica.com/science/mass-number" class="md-crosslink " data-show-preview="true">mass number</a>, of the nucleus gives approximately the mass measured on the so-called atomic-mass-unit (amu) scale. The numerical difference between the actual measured mass of an isotope and <em>A</em> is called either the mass excess or the <span id="ref496302"></span><a href="https://www.britannica.com/science/mass-defect" class="md-crosslink ">mass defect</a> (symbol Δ; <em>see</em> <span id="ref1243"></span>table).</p><span class="marker MOD4 mod-inline"></span><span class="md-raw-html"><div class="md-drag md-table-wrapper"><table> <caption> Abundances of the isotopes </caption> <thead> <tr> <th scope="col"> element </th> <th scope="col"> Z </th> <th scope="col"> symbol </th> <th scope="col"> A </th> <th scope="col"> abundance </th> <th scope="col"> mass excess </th> </tr> </thead> <tfoot> <tr> <td colspan="6"> Sources: G. Audi and A.H. Wapstra, "The 1995 Update to Atomic Mass Evaluation," Nuclear Physics, A595:409–480 (1995); K.J.R. Rosman and P.D.P. Taylor, "Isotopic Compositions of the Elements 1997," J. Phys. Chem. Ref. Data, 27:1275–85 (1995). </td> </tr> </tfoot> <tbody> <tr class="has-rs"> <td rowspan="" scope="row"> hydrogen </td> <td> 1 </td> <td> H </td> <td> 1 </td> <td> 99.9885 </td> <td> 7.289 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 2 </td> <td> 0.0151 </td> <td> 13.136 </td> </tr> <tr> <td scope="row"> helium </td> <td> 2 </td> <td> He </td> <td> 3 </td> <td> 0.000138 </td> <td> 14.931 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 4 </td> <td> 99.999863 </td> <td> 2.425 </td> </tr> <tr> <td scope="row"> lithium </td> <td> 3 </td> <td> Li </td> <td> 6 </td> <td> 7.59 </td> <td> 14.086 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 7 </td> <td> 92.41 </td> <td> 14.908 </td> </tr> <tr> <td scope="row"> beryllium </td> <td> 4 </td> <td> Be </td> <td> 9 </td> <td> 100 </td> <td> 11.348 </td> </tr> <tr> <td scope="row"> boron </td> <td> 5 </td> <td> B </td> <td> 10 </td> <td> 19.9 </td> <td> 12.051 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 11 </td> <td> 80.1 </td> <td> 8.668 </td> </tr> <tr> <td scope="row"> carbon </td> <td> 6 </td> <td> C </td> <td> 12 </td> <td> 98.93 </td> <td> 0 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 13 </td> <td> 1.07 </td> <td> 3.125 </td> </tr> <tr> <td scope="row"> nitrogen </td> <td> 7 </td> <td> N </td> <td> 14 </td> <td> 99.632 </td> <td> 2.863 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 15 </td> <td> 0.368 </td> <td> 0.101 </td> </tr> <tr> <td scope="row"> oxygen </td> <td> 8 </td> <td> O </td> <td> 16 </td> <td> 99.757 </td> <td> −4.737 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 17 </td> <td> 0.038 </td> <td> −0.809 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 18 </td> <td> 0.205 </td> <td> −0.782 </td> </tr> <tr> <td scope="row"> fluorine </td> <td> 9 </td> <td> F </td> <td> 19 </td> <td> 100 </td> <td> −1.487 </td> </tr> <tr> <td scope="row"> neon </td> <td> 10 </td> <td> Ne </td> <td> 20 </td> <td> 90.48 </td> <td> −7.042 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 21 </td> <td> 0.27 </td> <td> −5.732 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 22 </td> <td> 9.25 </td> <td> −8.024 </td> </tr> <tr> <td scope="row"> sodium </td> <td> 11 </td> <td> Na </td> <td> 23 </td> <td> 100 </td> <td> −9.529 </td> </tr> <tr> <td scope="row"> magnesium </td> <td> 12 </td> <td> Mg </td> <td> 24 </td> <td> 78.99 </td> <td> −13.933 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 25 </td> <td> 10.00 </td> <td> −13.193 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 26 </td> <td> 11.01 </td> <td> −16.214 </td> </tr> <tr> <td scope="row"> aluminum </td> <td> 13 </td> <td> Al </td> <td> 27 </td> <td> 100 </td> <td> −17.197 </td> </tr> <tr> <td scope="row"> silicon </td> <td> 14 </td> <td> Si </td> <td> 28 </td> <td> 92.2297 </td> <td> −21.493 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 29 </td> <td> 4.6832 </td> <td> −21.895 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 30 </td> <td> 3.0872 </td> <td> −24.433 </td> </tr> <tr> <td scope="row"> phosphorus </td> <td> 15 </td> <td> P </td> <td> 31 </td> <td> 100 </td> <td> −24.441 </td> </tr> <tr> <td scope="row"> sulfur </td> <td> 16 </td> <td> S </td> <td> 32 </td> <td> 94.93 </td> <td> −26.016 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 33 </td> <td> 0.76 </td> <td> −26.586 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 34 </td> <td> 4.29 </td> <td> −29.932 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 36 </td> <td> 0.02 </td> <td> −30.664 </td> </tr> <tr> <td scope="row"> chlorine </td> <td> 17 </td> <td> Cl </td> <td> 35 </td> <td> 75.78 </td> <td> −29.014 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 37 </td> <td> 24.22 </td> <td> −31.762 </td> </tr> <tr> <td scope="row"> argon </td> <td> 18 </td> <td> Ar </td> <td> 36 </td> <td> 0.3365 </td> <td> −30.230 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 38 </td> <td> 0.0632 </td> <td> −34.715 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 40 </td> <td> 99.6003 </td> <td> −35.040 </td> </tr> <tr> <td scope="row"> potassium </td> <td> 19 </td> <td> K </td> <td> 39 </td> <td> 93.2581 </td> <td> −33.807 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 40 </td> <td> 0.0117 </td> <td> −33.535 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 41 </td> <td> 6.7302 </td> <td> −35.559 </td> </tr> <tr> <td scope="row"> calcium </td> <td> 20 </td> <td> Ca </td> <td> 40 </td> <td> 96.941 </td> <td> −34.846 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 42 </td> <td> 0.647 </td> <td> −38.547 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 43 </td> <td> 0.135 </td> <td> −38.408 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 44 </td> <td> 2.086 </td> <td> −41.469 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 46 </td> <td> 0.004 </td> <td> −43.135 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 48 </td> <td> 0.187 </td> <td> −44.215 </td> </tr> <tr> <td scope="row"> scandium </td> <td> 21 </td> <td> Sc </td> <td> 45 </td> <td> 100 </td> <td> −41.069 </td> </tr> <tr> <td scope="row"> titanium </td> <td> 22 </td> <td> Ti </td> <td> 46 </td> <td> 8.25 </td> <td> −44.125 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 47 </td> <td> 7.44 </td> <td> −44.932 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 48 </td> <td> 73.72 </td> <td> −48.487 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 49 </td> <td> 5.41 </td> <td> −48.558 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 50 </td> <td> 5.18 </td> <td> −51.426 </td> </tr> <tr> <td scope="row"> vanadium </td> <td> 23 </td> <td> V </td> <td> 50 </td> <td> 0.250 </td> <td> −49.218 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 51 </td> <td> 99.750 </td> <td> −52.198 </td> </tr> <tr> <td scope="row"> chromium </td> <td> 24 </td> <td> Cr </td> <td> 50 </td> <td> 4.345 </td> <td> −50.254 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 52 </td> <td> 83.789 </td> <td> −55.413 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 53 </td> <td> 9.501 </td> <td> −55.281 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 54 </td> <td> 2.365 </td> <td> −56.928 </td> </tr> <tr> <td scope="row"> manganese </td> <td> 25 </td> <td> Mn </td> <td> 55 </td> <td> 100 </td> <td> −57.706 </td> </tr> <tr> <td scope="row"> iron </td> <td> 26 </td> <td> Fe </td> <td> 54 </td> <td> 5.845 </td> <td> −56.248 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 56 </td> <td> 91.754 </td> <td> −60.601 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 57 </td> <td> 2.119 </td> <td> −60.176 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 58 </td> <td> 0.282 </td> <td> −62.149 </td> </tr> <tr> <td scope="row"> cobalt </td> <td> 27 </td> <td> Co </td> <td> 59 </td> <td> 100 </td> <td> −62.224 </td> </tr> <tr> <td scope="row"> nickel </td> <td> 28 </td> <td> Ni </td> <td> 58 </td> <td> 68.0769 </td> <td> −60.223 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 60 </td> <td> 26.2231 </td> <td> −64.468 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 61 </td> <td> 1.1399 </td> <td> −64.217 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 62 </td> <td> 3.6345 </td> <td> −66.743 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 64 </td> <td> 0.9256 </td> <td> −67.096 </td> </tr> <tr> <td scope="row"> copper </td> <td> 29 </td> <td> Cu </td> <td> 63 </td> <td> 69.17 </td> <td> −65.576 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 65 </td> <td> 30.83 </td> <td> −67.260 </td> </tr> <tr> <td scope="row"> zinc </td> <td> 30 </td> <td> Zn </td> <td> 64 </td> <td> 48.63 </td> <td> −66.000 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 66 </td> <td> 27.90 </td> <td> −68.896 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 67 </td> <td> 4.10 </td> <td> −67.877 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 68 </td> <td> 18.75 </td> <td> −70.004 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 70 </td> <td> 0.62 </td> <td> −69.559 </td> </tr> <tr> <td scope="row"> gallium </td> <td> 31 </td> <td> Ga </td> <td> 69 </td> <td> 60.108 </td> <td> −69.321 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 71 </td> <td> 39.892 </td> <td> −70.137 </td> </tr> <tr> <td scope="row"> germanium </td> <td> 32 </td> <td> Ge </td> <td> 70 </td> <td> 20.84 </td> <td> −70.560 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 72 </td> <td> 27.54 </td> <td> −72.586 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 73 </td> <td> 7.73 </td> <td> −71.299 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 74 </td> <td> 36.28 </td> <td> −73.422 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 76 </td> <td> 7.61 </td> <td> −73.213 </td> </tr> <tr> <td scope="row"> arsenic </td> <td> 33 </td> <td> As </td> <td> 75 </td> <td> 100 </td> <td> −73.032 </td> </tr> <tr> <td scope="row"> selenium </td> <td> 34 </td> <td> Se </td> <td> 74 </td> <td> 0.89 </td> <td> −72.213 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 76 </td> <td> 9.37 </td> <td> −75.252 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 77 </td> <td> 7.63 </td> <td> −74.599 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 78 </td> <td> 23.77 </td> <td> −77.026 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 80 </td> <td> 49.61 </td> <td> −77.759 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 82 </td> <td> 8.73 </td> <td> −77.593 </td> </tr> <tr> <td scope="row"> bromine </td> <td> 35 </td> <td> Br </td> <td> 79 </td> <td> 50.69 </td> <td> −76.068 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 81 </td> <td> 49.31 </td> <td> −77.974 </td> </tr> <tr> <td scope="row"> krypton </td> <td> 36 </td> <td> Kr </td> <td> 78 </td> <td> 0.35 </td> <td> −74.160 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 80 </td> <td> 2.28 </td> <td> −77.893 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 82 </td> <td> 11.58 </td> <td> −80.589 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 83 </td> <td> 11.49 </td> <td> −79.982 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 84 </td> <td> 57.00 </td> <td> −82.431 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 86 </td> <td> 17.30 </td> <td> −83.266 </td> </tr> <tr> <td scope="row"> rubidium </td> <td> 37 </td> <td> Rb </td> <td> 85 </td> <td> 72.17 </td> <td> −82.168 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 87 </td> <td> 27.83 </td> <td> −84.595 </td> </tr> <tr> <td scope="row"> strontium </td> <td> 38 </td> <td> Sr </td> <td> 84 </td> <td> 0.56 </td> <td> −80.644 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 86 </td> <td> 9.86 </td> <td> −84.522 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 87 </td> <td> 7.00 </td> <td> −84.878 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 88 </td> <td> 82.58 </td> <td> −87.920 </td> </tr> <tr> <td scope="row"> yttrium </td> <td> 39 </td> <td> Y </td> <td> 89 </td> <td> 100 </td> <td> −87.702 </td> </tr> <tr> <td scope="row"> zirconium </td> <td> 40 </td> <td> Zr </td> <td> 90 </td> <td> 51.45 </td> <td> −88.768 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 91 </td> <td> 11.22 </td> <td> −87.891 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 92 </td> <td> 17.15 </td> <td> −88.455 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 94 </td> <td> 17.38 </td> <td> −87.266 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 96 </td> <td> 2.80 </td> <td> −85.441 </td> </tr> <tr> <td scope="row"> niobium </td> <td> 41 </td> <td> Nb </td> <td> 93 </td> <td> 100 </td> <td> −87.209 </td> </tr> <tr> <td scope="row"> molybdenum </td> <td> 42 </td> <td> Mo </td> <td> 92 </td> <td> 14.84 </td> <td> −86.805 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 94 </td> <td> 9.25 </td> <td> −88.410 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 95 </td> <td> 15.92 </td> <td> −87.708 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 96 </td> <td> 16.68 </td> <td> −88.791 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 97 </td> <td> 9.55 </td> <td> −87.541 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 98 </td> <td> 24.13 </td> <td> −88.112 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 100 </td> <td> 9.63 </td> <td> −86.184 </td> </tr> <tr> <td scope="row"> ruthenium </td> <td> 44 </td> <td> Ru </td> <td> 96 </td> <td> 5.54 </td> <td> −86.072 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 98 </td> <td> 1.87 </td> <td> −88.224 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 99 </td> <td> 12.76 </td> <td> −87.617 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 100 </td> <td> 12.60 </td> <td> −89.219 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 101 </td> <td> 17.06 </td> <td> −87.950 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 102 </td> <td> 31.55 </td> <td> −89.098 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 104 </td> <td> 18.62 </td> <td> −88.091 </td> </tr> <tr> <td scope="row"> rhodium </td> <td> 45 </td> <td> Rh </td> <td> 103 </td> <td> 100 </td> <td> −88.022 </td> </tr> <tr> <td scope="row"> palladium </td> <td> 46 </td> <td> Pd </td> <td> 102 </td> <td> 1.020 </td> <td> −87.926 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 104 </td> <td> 11.14 </td> <td> −89.391 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 105 </td> <td> 22.33 </td> <td> −88.414 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 106 </td> <td> 27.33 </td> <td> −89.905 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 108 </td> <td> 26.46 </td> <td> −89.522 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 110 </td> <td> 11.72 </td> <td> −88.350 </td> </tr> <tr> <td scope="row"> silver </td> <td> 47 </td> <td> Ag </td> <td> 107 </td> <td> 51.8392 </td> <td> −88.405 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 109 </td> <td> 48.1608 </td> <td> −88.720 </td> </tr> <tr> <td scope="row"> cadmium </td> <td> 48 </td> <td> Cd </td> <td> 106 </td> <td> 1.25 </td> <td> −87.134 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 108 </td> <td> 0.89 </td> <td> −89.253 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 110 </td> <td> 12.49 </td> <td> −90.350 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 111 </td> <td> 12.80 </td> <td> −89.254 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 112 </td> <td> 24.13 </td> <td> −90.581 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 113 </td> <td> 12.22 </td> <td> −89.050 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 114 </td> <td> 28.73 </td> <td> −90.021 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 116 </td> <td> 7.49 </td> <td> −88.720 </td> </tr> <tr> <td scope="row"> indium </td> <td> 49 </td> <td> In </td> <td> 113 </td> <td> 4.288 </td> <td> −89.366 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 115 </td> <td> 95.712 </td> <td> −89.537 </td> </tr> <tr> <td scope="row"> tin </td> <td> 50 </td> <td> Sn </td> <td> 112 </td> <td> 0.973 </td> <td> −88.659 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 114 </td> <td> 0.659 </td> <td> −90.558 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 115 </td> <td> 0.339 </td> <td> −90.033 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 116 </td> <td> 14.536 </td> <td> −91.525 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 117 </td> <td> 7.676 </td> <td> −90.398 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 118 </td> <td> 24.223 </td> <td> −91.653 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 119 </td> <td> 8.585 </td> <td> −90.067 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 120 </td> <td> 32.593 </td> <td> −91.103 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 122 </td> <td> 4.629 </td> <td> −89.944 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 124 </td> <td> 5.789 </td> <td> −88.236 </td> </tr> <tr> <td scope="row"> antimony </td> <td> 51 </td> <td> Sb </td> <td> 121 </td> <td> 57.213 </td> <td> −89.593 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 123 </td> <td> 42.787 </td> <td> −89.222 </td> </tr> <tr> <td scope="row"> tellurium </td> <td> 52 </td> <td> Te </td> <td> 120 </td> <td> 0.096 </td> <td> −89.405 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 122 </td> <td> 2.603 </td> <td> −90.311 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 123 </td> <td> 0.908 </td> <td> −89.169 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 124 </td> <td> 4.816 </td> <td> −90.523 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 125 </td> <td> 7.139 </td> <td> −89.028 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 126 </td> <td> 18.952 </td> <td> −90.070 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 128 </td> <td> 31.687 </td> <td> −88.994 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 130 </td> <td> 33.799 </td> <td> −87.353 </td> </tr> <tr> <td scope="row"> iodine </td> <td> 53 </td> <td> I </td> <td> 127 </td> <td> 100 </td> <td> −88.987 </td> </tr> <tr> <td scope="row"> xenon </td> <td> 54 </td> <td> Xe </td> <td> 124 </td> <td> 0.08913 </td> <td> −87.658 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 126 </td> <td> 0.08880 </td> <td> −89.173 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 128 </td> <td> 1.91732 </td> <td> −89.861 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 129 </td> <td> 26.43964 </td> <td> −89.697 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 130 </td> <td> 4.08271 </td> <td> −89.881 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 131 </td> <td> 21.17961 </td> <td> −88.416 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 132 </td> <td> 26.89157 </td> <td> −89.280 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 134 </td> <td> 10.44232 </td> <td> −88.124 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 136 </td> <td> 8.86590 </td> <td> −86.424 </td> </tr> <tr> <td scope="row"> cesium </td> <td> 55 </td> <td> Cs </td> <td> 133 </td> <td> 100 </td> <td> −88.076 </td> </tr> <tr> <td scope="row"> barium </td> <td> 56 </td> <td> Ba </td> <td> 130 </td> <td> 0.1058 </td> <td> −87.271 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 132 </td> <td> 0.1012 </td> <td> −88.440 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 134 </td> <td> 2.417 </td> <td> −88.954 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 135 </td> <td> 6.592 </td> <td> −87.856 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 136 </td> <td> 7.853 </td> <td> −88.892 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 137 </td> <td> 11.232 </td> <td> −87.727 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 138 </td> <td> 71.699 </td> <td> −88.267 </td> </tr> <tr> <td scope="row"> lanthanum </td> <td> 57 </td> <td> La </td> <td> 138 </td> <td> 0.09017 </td> <td> −86.529 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 139 </td> <td> 99.91 </td> <td> −87.236 </td> </tr> <tr> <td scope="row"> cerium </td> <td> 58 </td> <td> Ce </td> <td> 136 </td> <td> 0.186 </td> <td> −86.500 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 138 </td> <td> 0.251 </td> <td> −87.574 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 140 </td> <td> 88.449 </td> <td> −88.088 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 142 </td> <td> 11.114 </td> <td> −84.543 </td> </tr> <tr> <td scope="row"> praseodymium </td> <td> 59 </td> <td> Pr </td> <td> 141 </td> <td> 100 </td> <td> −86.026 </td> </tr> <tr> <td scope="row"> neodymium </td> <td> 60 </td> <td> Nd </td> <td> 142 </td> <td> 27.16 </td> <td> −85.960 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 143 </td> <td> 12.18 </td> <td> −84.012 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 144 </td> <td> 23.83 </td> <td> −83.758 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 145 </td> <td> 8.30 </td> <td> −81.442 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 146 </td> <td> 17.17 </td> <td> −80.936 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 148 </td> <td> 5.74 </td> <td> −77.418 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 150 </td> <td> 5.62 </td> <td> −73.694 </td> </tr> <tr> <td scope="row"> samarium </td> <td> 62 </td> <td> Sm </td> <td> 144 </td> <td> 3.0734 </td> <td> −81.976 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 147 </td> <td> 14.9934 </td> <td> −79.276 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 148 </td> <td> 11.2406 </td> <td> −79.347 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 149 </td> <td> 13.8189 </td> <td> −77.147 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 150 </td> <td> 7.3796 </td> <td> −77.061 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 152 </td> <td> 26.7421 </td> <td> −74.773 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 154 </td> <td> 22.7520 </td> <td> −72.465 </td> </tr> <tr> <td scope="row"> europium </td> <td> 63 </td> <td> Eu </td> <td> 151 </td> <td> 47.810 </td> <td> −74.663 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 153 </td> <td> 52.190 </td> <td> −73.377 </td> </tr> <tr> <td scope="row"> gadolinium </td> <td> 64 </td> <td> Gd </td> <td> 152 </td> <td> 0.2029 </td> <td> −74.717 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 154 </td> <td> 2.1809 </td> <td> −73.716 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 155 </td> <td> 14.7998 </td> <td> −72.080 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 156 </td> <td> 20.4664 </td> <td> −72.545 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 157 </td> <td> 15.6518 </td> <td> −70.834 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 158 </td> <td> 24.8347 </td> <td> −0.700 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 160 </td> <td> 21.8635 </td> <td> −67.952 </td> </tr> <tr> <td scope="row"> terbium </td> <td> 65 </td> <td> Tb </td> <td> 159 </td> <td> 100 </td> <td> −69.542 </td> </tr> <tr> <td scope="row"> dysprosium </td> <td> 66 </td> <td> Dy </td> <td> 156 </td> <td> 0.056 </td> <td> −70.534 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 158 </td> <td> 0.096 </td> <td> −70.417 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 160 </td> <td> 2.34 </td> <td> −69.682 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 161 </td> <td> 18.91 </td> <td> −68.065 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 162 </td> <td> 25.51 </td> <td> −68.190 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 163 </td> <td> 24.90 </td> <td> −66.390 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 164 </td> <td> 28.19 </td> <td> −65.977 </td> </tr> <tr> <td scope="row"> holmium </td> <td> 67 </td> <td> Ho </td> <td> 165 </td> <td> 100 </td> <td> −64.907 </td> </tr> <tr> <td scope="row"> erbium </td> <td> 68 </td> <td> Er </td> <td> 162 </td> <td> 0.137 </td> <td> −66.346 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 164 </td> <td> 1.609 </td> <td> −65.953 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 166 </td> <td> 33.61 </td> <td> −64.934 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 167 </td> <td> 22.93 </td> <td> −63.299 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 168 </td> <td> 26.79 </td> <td> −62.999 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 170 </td> <td> 14.93 </td> <td> −60.118 </td> </tr> <tr> <td scope="row"> thulium </td> <td> 69 </td> <td> Tm </td> <td> 169 </td> <td> 100 </td> <td> −61.282 </td> </tr> <tr> <td scope="row"> ytterbium </td> <td> 70 </td> <td> Yb </td> <td> 168 </td> <td> 0.127 </td> <td> −61.577 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 170 </td> <td> 3.04 </td> <td> −60.772 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 171 </td> <td> 14.28 </td> <td> −59.315 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 172 </td> <td> 21.83 </td> <td> −59.264 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 173 </td> <td> 16.13 </td> <td> −57.560 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 174 </td> <td> 31.83 </td> <td> −56.953 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 176 </td> <td> 12.76 </td> <td> −53.497 </td> </tr> <tr> <td scope="row"> lutetium </td> <td> 71 </td> <td> Lu </td> <td> 175 </td> <td> 97.416 </td> <td> −55.174 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 176 </td> <td> 2.584 </td> <td> −53.391 </td> </tr> <tr> <td scope="row"> hafnium </td> <td> 72 </td> <td> Hf </td> <td> 174 </td> <td> 0.1620 </td> <td> −55.852 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 176 </td> <td> 5.604 </td> <td> −54.584 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 177 </td> <td> 18.5953 </td> <td> −52.890 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 178 </td> <td> 27.811 </td> <td> −52.445 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 179 </td> <td> 13.6210 </td> <td> −50.473 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 180 </td> <td> 35.0802 </td> <td> −49.790 </td> </tr> <tr> <td scope="row"> tantalum </td> <td> 73 </td> <td> Ta </td> <td> 180 </td> <td> 0.0123 </td> <td> −48.935 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 181 </td> <td> 99.9877 </td> <td> −48.441 </td> </tr> <tr> <td scope="row"> tungsten </td> <td> 74 </td> <td> W </td> <td> 180 </td> <td> 0.1198 </td> <td> −49.643 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 182 </td> <td> 26.4985 </td> <td> −48.246 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 183 </td> <td> 14.3136 </td> <td> −46.366 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 184 </td> <td> 30.6422 </td> <td> −45.706 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 186 </td> <td> 28.4259 </td> <td> −42.511 </td> </tr> <tr> <td scope="row"> rhenium </td> <td> 75 </td> <td> Re </td> <td> 185 </td> <td> 37.398 </td> <td> −43.821 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 187 </td> <td> 62.602 </td> <td> −41.218 </td> </tr> <tr> <td scope="row"> osmium </td> <td> 76 </td> <td> Os </td> <td> 184 </td> <td> 0.0197 </td> <td> −44.254 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 186 </td> <td> 1.5859 </td> <td> −42.999 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 187 </td> <td> 1.9644 </td> <td> −41.220 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 188 </td> <td> 13.2434 </td> <td> −41.138 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 189 </td> <td> 16.1466 </td> <td> −38.988 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 190 </td> <td> 26.2584 </td> <td> −38.708 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 192 </td> <td> 40.7815 </td> <td> −35.882 </td> </tr> <tr> <td scope="row"> iridium </td> <td> 77 </td> <td> Ir </td> <td> 191 </td> <td> 37.272 </td> <td> −36.709 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 193 </td> <td> 62.728 </td> <td> −34.536 </td> </tr> <tr> <td scope="row"> platinum </td> <td> 78 </td> <td> Pt </td> <td> 190 </td> <td> 0.013634 </td> <td> −37.325 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 192 </td> <td> 0.782659 </td> <td> −36.296 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 194 </td> <td> 32.96700 </td> <td> −34.779 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 195 </td> <td> 33.831557 </td> <td> −32.812 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 196 </td> <td> 25.24166 </td> <td> −32.663 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 198 </td> <td> 7.16349 </td> <td> −29.923 </td> </tr> <tr> <td scope="row"> gold </td> <td> 79 </td> <td> Au </td> <td> 197 </td> <td> 100 </td> <td> −31.157 </td> </tr> <tr> <td scope="row"> mercury </td> <td> 80 </td> <td> Hg </td> <td> 196 </td> <td> 0.15344 </td> <td> −31.843 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 198 </td> <td> 9.968 </td> <td> −30.970 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 199 </td> <td> 16.873 </td> <td> −29.563 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 200 </td> <td> 23.096 </td> <td> −29.520 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 201 </td> <td> 13.181 </td> <td> −27.679 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 202 </td> <td> 29.863 </td> <td> −27.362 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 204 </td> <td> 6.865 </td> <td> −24.707 </td> </tr> <tr> <td scope="row"> thallium </td> <td> 81 </td> <td> Tl </td> <td> 203 </td> <td> 29.524 </td> <td> −25.775 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 205 </td> <td> 70.476 </td> <td> −23.834 </td> </tr> <tr> <td scope="row"> lead </td> <td> 82 </td> <td> Pb </td> <td> 204 </td> <td> 1.4245 </td> <td> −25.123 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 206 </td> <td> 24.1447 </td> <td> −23.801 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 207 </td> <td> 22.0827 </td> <td> −22.467 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 208 </td> <td> 52.3481 </td> <td> −21.764 </td> </tr> <tr> <td scope="row"> bismuth </td> <td> 83 </td> <td> Bi </td> <td> 209 </td> <td> 100 </td> <td> −18.273 </td> </tr> <tr> <td scope="row"> thorium </td> <td> 90 </td> <td> Th </td> <td> 232 </td> <td> 100 </td> <td> 35.444 </td> </tr> <tr> <td scope="row"> uranium </td> <td> 92 </td> <td> U </td> <td> 234 </td> <td> 0.00548 </td> <td> 38.141 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 235 </td> <td> 0.7200 </td> <td> 40.914 </td> </tr> <tr> <td scope="row"></td> <td></td> <td></td> <td> 238 </td> <td> 99.2745 </td> <td> 47.304 </td> </tr> </tbody> </table></div> </span><span class="marker PREMOD5 mod-inline"></span><p class="topic-paragraph">The specification of <em>Z</em>, <em>A</em>, and the <a href="https://www.britannica.com/science/chemical-symbol" class="md-crosslink autoxref " data-show-preview="true">chemical symbol</a> (a one- or two-letter abbreviation of the element’s name, say Sy) in the form <sup><em>A</em></sup><sub><em>Z</em></sub>Sy identifies an isotope adequately for most purposes. Thus, in the standard notation, <sup>1</sup><sub>1</sub>H refers to the simplest isotope of hydrogen and <sup>235</sup><sub>92</sub>U to an isotope of uranium widely used for <a href="https://www.britannica.com/technology/nuclear-power" class="md-crosslink autoxref " data-show-preview="true">nuclear power</a> generation and nuclear weapons fabrication. (Authors who do not wish to use symbols sometimes write out the element name and mass number—hydrogen-1 and <a href="https://www.britannica.com/science/uranium-235" class="md-crosslink autoxref " data-show-preview="true">uranium-235</a> in the examples above.)</p><a class="link-module shadow-sm d-block qa-quiz-module" href="/quiz/facts-you-should-know-the-periodic-table-quiz" data-link-module-iframe-link=""> <img loading="lazy" src="https://cdn.britannica.com/58/203458-131-D94E9327/periodic-table-concept.jpg" alt="Periodic Table of the elements concept image (chemistry)" class="rounded-sm mr-15" width="70" /> <div class="line-clamp clamp-5"> <div class="module-title bg-green">Britannica Quiz</div> <div class="font-weight-semi-bold mt-5">Facts You Should Know: The Periodic Table Quiz</div> </div> </a><div class="one-good-fact-module"> </div><span class="marker MOD5 mod-inline"></span><span class="marker PREMOD6 mod-inline"></span><p class="topic-paragraph">The term <span id="ref496303"></span><a href="https://www.britannica.com/science/nuclide" class="md-crosslink " data-show-preview="true"><em>nuclide</em></a> is used to describe particular isotopes, notably in cases where the nuclear rather than the chemical properties of an atom are to be <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="emphasized" href="https://www.britannica.com/dictionary/emphasized" data-type="EB">emphasized</a>. The lexicon of isotopes includes three other frequently used terms: <span id="ref496304"></span><a href="https://www.britannica.com/science/isotone" class="md-crosslink " data-show-preview="true"><em>isotones</em></a> for isotopes of different elements with the same number of neutrons, <span id="ref496305"></span><a href="https://www.britannica.com/science/isobar-nuclear-physics" class="md-crosslink " data-show-preview="true"><em>isobars</em></a> for isotopes of different elements with the same mass number, and <span id="ref496306"></span><a href="https://www.britannica.com/science/isomer-nuclear-physics" class="md-crosslink " data-show-preview="true"><em>isomers</em></a> for isotopes identical in all respects except for the total energy content of the nuclei.</p><span class="marker MOD6 mod-inline"></span></section> <span class="marker end-of-content"></span><span class="marker after-article"></span></div> <div id="chatbot-root"></div> </div> </div> </div> <div class="ai-dialog-placeholder"></div> </div> </div> <aside class="col-md-da-320"></aside> </div> </div> </div> </div> </article></div> </div></div> </div> </main> <div id="md-footer"></div> <noscript><iframe src="//www.googletagmanager.com/ns.html?id=GTM-5W6NC8" height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript> <script type="text/javascript" id="_informizely_script_tag"> var IzWidget = IzWidget || {}; (function (d) { var scriptElement = d.createElement('script'); scriptElement.type = 'text/javascript'; scriptElement.async = true; scriptElement.src = "https://insitez.blob.core.windows.net/site/f780f33e-a610-4ac2-af81-3eb184037547.js"; var node = d.getElementById('_informizely_script_tag'); node.parentNode.insertBefore(scriptElement, node); } )(document); </script>  <script> window.ap3c = window.ap3c || {}; var ap3c = window.ap3c; ap3c.cmd = ap3c.cmd || []; ap3c.cmd.push(function() { ap3c.init('ZO4siT4cLwnykPnzZWJtd3Byb2Q', 'https://engage.email.britannica.com/'); ap3c.track({v: 0}); }); ap3c.activity = function(act) { ap3c.act = (ap3c.act || []); ap3c.act.push(act); }; var s, t; s = document.createElement('script'); s.type = 'text/javascript'; s.src = "https://engage.email.britannica.com/app.js"; t = document.getElementsByTagName('script')[0]; t.parentNode.insertBefore(s, t); </script> <script class="marketing-page-info" type="application/json"> {"pageType":"Topic","templateName":"DESKTOP","pageNumber":1,"pagesTotal":6,"pageId":296583,"pageLength":541,"initialLoad":true,"lastPageOfScroll":false} </script> <script class="marketing-content-info" type="application/json"> [] </script> <script src="https://cdn.britannica.com/mendel-resources/3-130/js/libs/jquery-3.5.0.min.js?v=3.130.14"></script> <script type="text/javascript" data-type="Init Mendel Code Splitting"> (function() { $.ajax({ dataType: 'script', cache: true, url: 'https://cdn.britannica.com/mendel-resources/3-130/dist/topic-page.js?v=3.130.14' }); })(); </script> <script class="analytics-metadata" type="application/json"> {"leg":"B","adLeg":"B","userType":"ANONYMOUS","pageType":"Topic","pageSubtype":null,"articleTemplateType":"PAGINATED","gisted":false,"pageNumber":1,"hasSummarizeButton":false,"hasAskButton":false} </script> <script type="text/javascript"> EBStat={accountId:-1,hostnameOverride:'webstats.eb.com',domain:'www.britannica.com', json:''}; </script> <script type="text/javascript"> ( function() { $.ajax( { dataType: 'script', cache: true, url: '//www.britannica.com/webstats/mendelstats.js?v=1' } ) .done( function() { try {writeStat(null,EBStat);} catch(err){} } ); })(); </script> <div id="bc-fixed-dialogue"></div> </body> </html>

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Isotope | Examples & Definition | Britannica