Praseodymium | Rare Earth Element, Atomic Number 59

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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 gtm-byline font-12 byline-contributor text-decoration-underline"> The Editors of Encyclopaedia Britannica</span></div> <div class="last-updated font-12 font-serif"> <a class="byline-edit-history" href="https://www.britannica.com/science/praseodymium/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/Carl-Auer-Freiherr-von-Welsbach" topicid="639495">Carl Auer, Freiherr von Welsbach</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/chemical-element" topicid="108636">chemical element</a></dd> <dd><a href="/science/rare-earth-element" topicid="491579">rare-earth element</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 class="text-center"> <a class="btn btn-sm btn-link p-0" href="/facts/praseodymium"> See all related content </a> </div> </div> </div> </div><span class="marker before-article"></span><section data-level="1" id="ref1"><span class="marker PREMOD1 mod-inline"></span><p class="topic-paragraph"><strong><span id="ref56626"></span>praseodymium (Pr)</strong>, <a href="https://www.britannica.com/science/chemical-element" class="md-crosslink " data-show-preview="true">chemical element</a>, a <a href="https://www.britannica.com/science/rare-earth-element" class="md-crosslink " data-show-preview="true">rare-earth metal</a> of the <a href="https://www.britannica.com/science/lanthanide" class="md-crosslink " data-show-preview="true">lanthanide</a> series of the <a href="https://www.britannica.com/science/periodic-table" class="md-crosslink " data-show-preview="true">periodic table</a>.</p><span class="marker MOD1 mod-inline"></span><span class="marker PREMOD2 mod-inline"></span><p class="topic-paragraph">Praseodymium is a moderately soft, ductile, and <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="malleable" href="https://www.merriam-webster.com/dictionary/malleable" data-type="MW">malleable</a> silvery white <a href="https://www.britannica.com/science/metal-chemistry" class="md-crosslink " data-show-preview="true">metal</a>. It rapidly displaces <a href="https://www.britannica.com/science/hydrogen" class="md-crosslink " data-show-preview="true">hydrogen</a> from <a href="https://www.britannica.com/science/water" class="md-crosslink " data-show-preview="true">water</a> in diluted <a href="https://www.britannica.com/science/acid" class="md-crosslink " data-show-preview="true">acids</a> (except hydrofluoric acid [HF]) and slowly oxidizes in <a href="https://www.britannica.com/science/air" class="md-crosslink " data-show-preview="true">air</a>, developing a green-yellowish <a href="https://www.britannica.com/science/oxide" class="md-crosslink autoxref " data-show-preview="true">oxide</a> coating with complex and varying <a href="https://www.britannica.com/science/stoichiometry" class="md-crosslink " data-show-preview="true">stoichiometry</a> that can be expressed using a generic formula PrO<sub><em>x</em></sub> (1.5 ≤ <em>x</em> ≤ 2). The metal is best stored sealed in a plastic covering either in vacuum or in an inert atmosphere. Praseodymium is strongly <a href="https://www.britannica.com/science/paramagnetism" class="md-crosslink " data-show-preview="true">paramagnetic</a>, and an unstrained single-<a href="https://www.britannica.com/science/crystal" class="md-crosslink " data-show-preview="true">crystal</a> sample will order <a href="https://www.britannica.com/science/antiferromagnetism" class="md-crosslink " data-show-preview="true">antiferromagnetically</a> at 0.03 <a href="https://www.britannica.com/science/potassium" class="md-crosslink autoxref " data-show-preview="true">K</a> (−273.12 <a href="https://www.britannica.com/technology/Celsius-temperature-scale" class="md-crosslink autoxref " data-show-preview="true">°C</a>, or −459.62 °F). However, if praseodymium is strained, it may order at temperatures as high as about 20 K (−253 °C, or −424 °F).</p><span class="marker MOD2 mod-inline"></span><span class="marker PREMOD3 mod-inline"></span><p class="topic-paragraph">Praseodymium was discovered in didymia, a mixture of several rare-earth oxides. From it, by repeated fractional crystallization of ammonium didymium nitrate, Austrian chemist <span id="ref56628"></span><a href="https://www.britannica.com/biography/Carl-Auer-Freiherr-von-Welsbach" class="md-crosslink " data-show-preview="true">Carl Auer von Welsbach</a> in 1885 separated salts of the elements praseodymium (the green fraction) and <a href="https://www.britannica.com/science/neodymium" class="md-crosslink " data-show-preview="true">neodymium</a> (the pink fraction). Praseodymium occurs in minerals such as <a href="https://www.britannica.com/science/monazite" class="md-crosslink " data-show-preview="true">monazite</a> and <a href="https://www.britannica.com/science/bastnaesite" class="md-crosslink " data-show-preview="true">bastnasite</a> and as one of the products of <a href="https://www.britannica.com/science/nuclear-fission" class="md-crosslink " data-show-preview="true">nuclear fission</a>.</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><span class="marker MOD3 mod-inline"></span><span class="marker PREMOD4 mod-inline"></span><p class="topic-paragraph">Natural praseodymium is entirely the stable <a href="https://www.britannica.com/science/isotope" class="md-crosslink " data-show-preview="true">isotope</a> praseodymium-141. <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="Excluding" href="https://www.britannica.com/dictionary/Excluding" data-type="EB">Excluding</a> nuclear isomers, a total of 38 <a href="https://www.britannica.com/science/radioactive-isotope" class="md-crosslink " data-show-preview="true">radioactive isotopes</a> of praseodymium have been reported. They range in mass from 121 to 159 and have <a href="https://www.britannica.com/science/half-life-radioactivity" class="md-crosslink " data-show-preview="true">half-lives</a> from 10 milliseconds (praseodymium-121) to 13.57 days (praseodymium-143).</p><span class="marker MOD4 mod-inline"></span><span class="marker PREMOD5 mod-inline"></span><p class="topic-paragraph">This element is commercially separated and purified by liquid-liquid extraction or ion-exchange techniques. The metal is prepared by <a href="https://www.britannica.com/science/electrolysis" class="md-crosslink " data-show-preview="true">electrolysis</a> of fused anhydrous halides or by the metallothermic reduction of the fluoride or chloride with <a href="https://www.britannica.com/science/calcium" class="md-crosslink " data-show-preview="true">calcium</a>. Praseodymium exists in two allotropic (structural) forms. The α-phase is double close-packed hexagonal with <em>a</em> = 3.6721 Å and <em>c</em> = 11.8326 Å at room temperature. The β-phase is body-centred cubic with <em>a</em> = 4.13 Å at 821 °C (1,510 °F).</p><span class="marker MOD5 mod-inline"></span><span class="marker PREMOD6 mod-inline"></span><p class="topic-paragraph">Praseodymium is a minor <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="constituent" href="https://www.merriam-webster.com/dictionary/constituent" data-type="MW">constituent</a> of <a href="https://www.britannica.com/technology/misch-metal" class="md-crosslink " data-show-preview="true">misch metal</a>, which is used to make lighter flints and as alloying additions to ferrous and nonferrous <a href="https://www.britannica.com/technology/alloy" class="md-crosslink " data-show-preview="true">alloys</a>. The metal is also used as an addition to Nd<sub>2</sub><a href="https://www.britannica.com/science/iron-chemical-element" class="md-crosslink autoxref " data-show-preview="true">Fe</a><sub>14</sub>B permanent <a href="https://www.britannica.com/science/magnet" class="md-crosslink " data-show-preview="true">magnet</a> alloys leading to a reduction of the amount of neodymium required. Praseodymium-stabilized <a href="https://www.britannica.com/science/zirconia" class="md-crosslink " data-show-preview="true">zirconia</a> (ZrO<sub>2</sub>) is the foundation of <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="synthetic" href="https://www.merriam-webster.com/dictionary/synthetic" data-type="MW">synthetic</a> green-coloured <a href="https://www.britannica.com/science/gemstone" class="md-crosslink " data-show-preview="true">gems</a>. A mixture of praseodymium and neodymium is the active component in didymium <a href="https://www.britannica.com/technology/glass" class="md-crosslink " data-show-preview="true">glass</a>, used for goggles to protect the eyes of glassblowers and welders. Praseodymium <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="compounds" href="https://www.merriam-webster.com/dictionary/compounds" data-type="MW">compounds</a> are also used to produce light green to yellow colours in <a href="https://www.britannica.com/technology/ceramic-composition-and-properties" class="md-crosslink " data-show-preview="true">ceramics</a> and other glasses.</p><div class="one-good-fact-module"> </div><span class="marker MOD6 mod-inline"></span><span class="marker PREMOD7 mod-inline"></span><p class="topic-paragraph">Praseodymium forms trivalent compounds such as the olive-green oxide Pr<sub>2</sub><a href="https://www.britannica.com/science/oxygen" class="md-crosslink autoxref " data-show-preview="true">O</a><sub>3</sub>, which dissolves readily in acids to yield green trivalent praseodymium salts. The tetravalent blackish purple dioxide PrO<sub>2</sub> is known, but the Pr<sup>4+</sup> ion is unknown in aqueous solution.</p><div class="module-spacing"> <DIV class="marketing-INLINE_SUBSCRIPTION marketing-content" data-marketing-id="INLINE_SUBSCRIPTION"><style> .student-promo-banner-wrapper { container-type: inline-size; margin-bottom: 15px; } @container (min-width: 475px) { .student-promo-banner { flex-direction: row; } .student-promo-banner-img-wrapper { margin-bottom: 0; margin-right: 10px; justify-content: flex-start; } .student-promo-banner-text-wrapper { text-align: left; margin-bottom: 0px; margin-left: 10px; } .student-promo-banner-button-wrapper { margin-right: 0; } }</style> <div class="student-promo-banner-wrapper"> <div class="student-promo-banner d-flex flex-column align-items-center bg-blue rounded p-20"> <div class="student-promo-banner-img-wrapper mb-20 mr-0 d-flex justify-content-center"> <img class="rounded" style="max-width: 100px; min-width: 80px" src="https://cdn.britannica.com/marketing/BlueThistle.webp" /> </div> <div class="student-promo-banner-text-wrapper ml-0 mb-10 text-center text-white"> <div class="h2 mb-10">Get Unlimited Access</div> <div class="h4 font-weight-semi-bold">Try Britannica Premium for free and discover more.</div> </div> <div class="student-promo-banner-button-wrapper d-flex justify-content-center align-items-center ml-auto mr-auto"> <a class="btn btn-m btn-orange" href="https://premium.britannica.com/premium-membership/?utm_source=premium&utm_medium=inline-cta&utm_campaign=black-friday-2024">Subscribe</a> </div> </div> </div> </DIV></div><span class="marker MOD7 mod-inline"></span><div class="text-center pb-20"><div class="md-table-wrapper"><table class="md-element-table"><caption>Element Properties</caption><tbody><tr><th scope="row">atomic number</th><td>59</td></tr><tr><th scope="row">atomic weight</th><td>140.90765</td></tr><tr><th scope="row">melting point</th><td>931 °C (1,708 °F)</td></tr><tr><th scope="row">boiling point</th><td>3,520 °C (6,368 °F)</td></tr><tr><th scope="row">specific gravity</th><td>6.773 (24 °C, or 75 °F)</td></tr><tr><th scope="row">oxidation states</th><td>+3, +4</td></tr><tr><th scope="row">electron configuration</th><td>[Xe]4<em>f</em><sup> </sup><sup>3</sup>6<em>s</em><sup>2</sup></td></tr></tbody></table></div></div></section> <span class="md-signature">This article was most recently revised and updated by <a href="/editor/Erik-Gregersen/6723">Erik Gregersen</a>.</span><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 || {}; 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Praseodymium | Rare Earth Element, Atomic Number 59 | Britannica