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Lutetium | Rare Earth Element, Atomic Number 71 | Britannica
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overflow-hidden text-nowrap ml-15"> <a href="https://cdn.britannica.com/29/22329-050-FC45A9BB/Lutetium-symbol-Lu-square-periodic-table-some.jpg" data-href="/media/1/351924/64396" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/29/22329-004-2FE2CE41/Lutetium-symbol-Lu-square-periodic-table-some.jpg" alt="lutetium" height="50" /> </a> <a href="" data-href="/media/1/351924/299687" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/13/255013-049-6477CC72/periodic-table-banner.jpg" alt="Explore an interactive periodic table of the elements" height="50" /> </a> <a href="https://cdn.britannica.com/38/6038-050-DC1FDAEA/ionization-energy-element-atom-electron-energies-nonmetal.jpg" data-href="/media/1/351924/647" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/38/6038-004-134735D2/ionization-energy-element-atom-electron-energies-nonmetal.jpg" 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data-href="/media/1/351924/64396">lutetium</a> <span><span>Properties of lutetium.</span></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> </figcaption> </figure> </div><div class="topic-header"> <div class="d-flex align-items-top justify-content-between"> <div class="d-flex flex-column"> <div> <div> <h1>lutetium</h1></div> </div> <div class="topic-identifier font-16 font-md-20">chemical element</div> </div> </div> <div class="d-none d-sm-flex flex-row"> <div class="mr-10 mb-15"> <button class="ai-ask-button btn border-2 btn-sm js-inline-ai-ask-button btn-outline-red-400 border-red-400"> Ask the Chatbot a Question </button> </div> <div class="d-none d-sm-block md-topic-tools qa-action-buttons mb-15" data-topic-id="351924"> <button class="js-tooltip btn btn-sm btn-outline-blue border pr-10 border-2" > <em class="material-icons md-icon ml-n10 my-n5 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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/lutetium/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>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> <dd><a href="/science/lutetium-176" topicid="351938">lutetium-176</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/lutetium"> See all related content </a> </div> </div> </div> </div><!--[BEFORE-ARTICLE]--><span class="marker before-article"></span><section data-level="1" id="ref1"><!--[PREMOD1]--><span class="marker PREMOD1 mod-inline"></span><p class="topic-paragraph"><strong><span id="ref9895"></span>lutetium (Lu)</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>, that is the <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="densest" href="https://www.britannica.com/dictionary/densest" data-type="EB">densest</a> and the highest-melting rare-earth element and the last member of the lanthanide series.</p><!--[MOD1]--><span class="marker MOD1 mod-inline"></span><!--[PREMOD2]--><span class="marker PREMOD2 mod-inline"></span><p class="topic-paragraph">In its pure form, lutetium <a href="https://www.britannica.com/science/metal-chemistry" class="md-crosslink " data-show-preview="true">metal</a> is silvery white and stable in <a href="https://www.britannica.com/science/air" class="md-crosslink " data-show-preview="true">air</a>. The metal is easily dissolved in diluted <a href="https://www.britannica.com/science/acid" class="md-crosslink " data-show-preview="true">acids</a>—except hydrofluoric acid (HF), in which a protective layer of LuF<sup>3</sup> forms on the surface and prevents the metal from further dissolution. The metal is <a href="https://www.britannica.com/science/paramagnetism" class="md-crosslink " data-show-preview="true">paramagnetic</a> from 0 <a href="https://www.britannica.com/science/potassium" class="md-crosslink autoxref " data-show-preview="true">K</a> (−273 °C, or −460 °F) to its <a href="https://www.britannica.com/science/melting-point" class="md-crosslink autoxref " data-show-preview="true">melting point</a> at 1,936 K (1,663 °C, or 3,025 °F) with a temperature-independent <a href="https://www.britannica.com/science/magnetic-susceptibility" class="md-crosslink autoxref " data-show-preview="true">magnetic susceptibility</a> between approximately 4 and 300 K (−269 and 27 °C, or −452 and 80 °F). It becomes <a href="https://www.britannica.com/science/superconductivity" class="md-crosslink " data-show-preview="true">superconducting</a> at 0.022 K (−273.128 °C, or −459.63 °F) and <a href="https://www.britannica.com/science/pressure" class="md-crosslink " data-show-preview="true">pressures</a> <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="exceeding" href="https://www.britannica.com/dictionary/exceeding" data-type="EB">exceeding</a> 45 kilobars.</p><!--[MOD2]--><span class="marker MOD2 mod-inline"></span><!--[PREMOD3]--><span class="marker PREMOD3 mod-inline"></span><p class="topic-paragraph">Lutetium was discovered in 1907–08 by Austrian chemist <span id="ref9896"></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> and <span id="ref9897"></span><a href="https://www.britannica.com/biography/Georges-Urbain" class="md-crosslink ">Georges Urbain</a>, working independently. Urbain derived the name for the element from Lutetia, the ancient Roman name for <a href="https://www.britannica.com/place/Paris" class="md-crosslink " data-show-preview="true">Paris</a>, to honour his native city. The name lutetium became widely accepted except in Germany, where it was commonly called cassiopeium until the 1950s. One of the rarest of the rare earths, lutetium occurs in rare-earth <a href="https://www.britannica.com/science/mineral-chemical-compound" class="md-crosslink " data-show-preview="true">minerals</a> such as laterite clays, <a href="https://www.britannica.com/science/xenotime" class="md-crosslink " data-show-preview="true">xenotime</a>, and <a href="https://www.britannica.com/science/euxenite" class="md-crosslink " data-show-preview="true">euxenite</a>. Though lutetium composes only trace mounts (less than 0.1 percent by weight) of the commercially important minerals <a href="https://www.britannica.com/science/bastnaesite" class="md-crosslink " data-show-preview="true">bastnasite</a> and <a href="https://www.britannica.com/science/monazite" class="md-crosslink " data-show-preview="true">monazite</a>, it has proved <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="feasible" href="https://www.merriam-webster.com/dictionary/feasible" data-type="MW">feasible</a> to extract the metal as a by-product. Lutetium is also found in 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/periodic-table-names-symbols-quiz" data-link-module-iframe-link=""> <img loading="lazy" src="https://cdn.britannica.com/66/215466-131-16036BD8/Concept-artwork-periodic-table-elements.jpg" alt="Concept artwork on the periodic table of elements." 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">118 Names and Symbols of the Periodic Table Quiz</div> </div> </a><!--[MOD3]--><span class="marker MOD3 mod-inline"></span><!--[PREMOD4]--><span class="marker PREMOD4 mod-inline"></span><p class="topic-paragraph">Natural lutetium consists of two <a href="https://www.britannica.com/science/isotope" class="md-crosslink " data-show-preview="true">isotopes</a>: stable <span id="ref1030678"></span>lutetium-175 (97.4 percent) and radioactive <span id="ref1030677"></span>lutetium-176 (2.6 percent, 3.76 × 10<sup>10</sup>-year <a href="https://www.britannica.com/science/half-life-radioactivity" class="md-crosslink " data-show-preview="true">half-life</a>). The <a href="https://www.britannica.com/science/radioactive-isotope" class="md-crosslink " data-show-preview="true">radioactive isotope</a> is used to determine the age of <a href="https://www.britannica.com/science/meteorite" class="md-crosslink " data-show-preview="true">meteorites</a> relative to that of <a href="https://www.britannica.com/place/Earth" class="md-crosslink " data-show-preview="true">Earth</a>. In addition to lutetium-176, and not counting nuclear isomers, 33 more radioactive isotopes of lutetium are known. They range in mass from 150 to 184; the least stable isotope (lutetium-150) has a half-life of 45 milliseconds, and the most stable isotope is lutetium-176.</p><!--[MOD4]--><span class="marker MOD4 mod-inline"></span><!--[PREMOD5]--><span class="marker PREMOD5 mod-inline"></span><p class="topic-paragraph">Separation and purification are accomplished by liquid-liquid extraction or ion-exchange techniques. The metal is prepared by metallothermic reduction of the anhydrous halides by <a href="https://www.britannica.com/science/alkali-metal" class="md-crosslink " data-show-preview="true">alkali</a> or <a href="https://www.britannica.com/science/alkaline-earth-metal" class="md-crosslink " data-show-preview="true">alkaline-earth metals</a>. Lutetium is monomorphic and has a close-packed hexagonal structure with <em>a</em> = 3.5052 Å and <em>c</em> = 5.5494 Å at room temperature.</p><div class="one-good-fact-module"> </div><!--[MOD5]--><span class="marker MOD5 mod-inline"></span><!--[PREMOD6]--><span class="marker PREMOD6 mod-inline"></span><p class="topic-paragraph">Lutetium is used in research. Its <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 used as hosts for scintillators and <a href="https://www.britannica.com/science/X-ray" class="md-crosslink " data-show-preview="true">X-ray</a> <a href="https://www.britannica.com/science/phosphor" class="md-crosslink " data-show-preview="true">phosphors</a>, and the oxide is used in optical <a href="https://www.britannica.com/technology/lens-optics" class="md-crosslink " data-show-preview="true">lenses</a>. The element behaves as a typical rare earth, forming a series of compounds in <a href="https://www.britannica.com/science/oxidation-number" class="md-crosslink autoxref " data-show-preview="true">oxidation state</a> +3, such as lutetium sesquioxide, sulfate, and chloride.</p><!--[MOD6]--><span class="marker MOD6 mod-inline"></span><div class="mb-20"><div class="w-100"><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="299687" data-asm-type="infogram"><div class="md-assembly-wrapper card-media " data-type="infogram"><script id="infogram_0__/z8pqlTWwRHqAnaNwFRkn" src="https://e.infogram.com/js/dist/embed.js?Itp" type="text/javascript" title="Explore an interactive periodic table of the elements"></script></div></figure></div></div><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>71</td></tr><tr><th scope="row">atomic weight</th><td>174.967</td></tr><tr><th scope="row">melting point</th><td>1,663 °C (3,025 °F)</td></tr><tr><th scope="row">boiling point</th><td>3,402 °C (6,156 °F)</td></tr><tr><th scope="row">specific gravity</th><td>9.841 (24 °C, or 75 °F)</td></tr><tr><th scope="row">oxidation state</th><td>+3</td></tr><tr><th scope="row">electron configuration</th><td>[Xe]4<em>f</em><sup> 14</sup>5<em>d</em><sup>1</sup>6<em>s</em><sup>2</sup></td></tr></tbody></table></div></div></section> <span class="md-signature"><a href="/editor/The-Editors-of-Encyclopaedia-Britannica/4419">The Editors of Encyclopaedia Britannica</a></span> <span class="md-signature">This article was most recently revised and updated by <a href="/editor/rick-livingston/12680385">Rick Livingston</a>.</span><!--[END-OF-CONTENT]--><span class="marker end-of-content"></span><!--[AFTER-ARTICLE]--><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> <!-- Ortto ebmwprod capture code --> <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":1,"pageId":351924,"pageLength":458,"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":"MEDIUM","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>