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href="https://cs.wikipedia.org/wiki/Radon-222" title="Radon-222 – Czech" lang="cs" hreflang="cs" data-title="Radon-222" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%B1%D8%A7%D8%AF%D9%88%D9%86-%DB%B2%DB%B2%DB%B2" title="رادون-۲۲۲ – Persian" lang="fa" hreflang="fa" data-title="رادون-۲۲۲" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Radon_222" title="Radon 222 – French" lang="fr" hreflang="fr" data-title="Radon 222" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Radon-222" title="Radon-222 – Indonesian" lang="id" hreflang="id" data-title="Radon-222" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-ia mw-list-item"><a href="https://ia.wikipedia.org/wiki/Radon-222" title="Radon-222 – Interlingua" lang="ia" hreflang="ia" data-title="Radon-222" data-language-autonym="Interlingua" data-language-local-name="Interlingua" class="interlanguage-link-target"><span>Interlingua</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Radon-222" title="Radon-222 – Dutch" lang="nl" hreflang="nl" data-title="Radon-222" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E3%83%A9%E3%83%89%E3%83%B3222" title="ラドン222 – Japanese" lang="ja" hreflang="ja" data-title="ラドン222" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-pnb mw-list-item"><a href="https://pnb.wikipedia.org/wiki/%D8%B1%DB%8C%DA%88%D9%88%D9%86-222" title="ریڈون-222 – Western Punjabi" lang="pnb" hreflang="pnb" data-title="ریڈون-222" data-language-autonym="پنجابی" data-language-local-name="Western Punjabi" class="interlanguage-link-target"><span>پنجابی</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%A0%D0%B0%D0%B4%D0%BE%D0%BD-222" title="Радон-222 – Russian" lang="ru" hreflang="ru" data-title="Радон-222" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Radon-222" title="Radon-222 – Turkish" lang="tr" hreflang="tr" data-title="Radon-222" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-ur mw-list-item"><a href="https://ur.wikipedia.org/wiki/%D8%B1%DB%8C%DA%88%D9%88%D9%86-222" title="ریڈون-222 – Urdu" lang="ur" hreflang="ur" data-title="ریڈون-222" data-language-autonym="اردو" data-language-local-name="Urdu" class="interlanguage-link-target"><span>اردو</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E6%B0%A1-222" title="氡-222 – Chinese" lang="zh" hreflang="zh" data-title="氡-222" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a 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.infobox-3cols-child{margin:auto}.mw-parser-output .infobox .navbar{font-size:100%}@media screen{html.skin-theme-clientpref-night .mw-parser-output .infobox-full-data:not(.notheme)>div:not(.notheme)[style]{background:#1f1f23!important;color:#f8f9fa}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .infobox-full-data:not(.notheme) div:not(.notheme){background:#1f1f23!important;color:#f8f9fa}}@media(min-width:640px){body.skin--responsive .mw-parser-output .infobox-table{display:table!important}body.skin--responsive .mw-parser-output .infobox-table>caption{display:table-caption!important}body.skin--responsive .mw-parser-output .infobox-table>tbody{display:table-row-group}body.skin--responsive .mw-parser-output .infobox-table tr{display:table-row!important}body.skin--responsive .mw-parser-output .infobox-table th,body.skin--responsive .mw-parser-output .infobox-table td{padding-left:inherit;padding-right:inherit}}</style><table class="infobox"><caption class="infobox-title">Radon-222, <sup>222</sup>Rn</caption><tbody><tr><th colspan="2" class="infobox-header" style="background:#eee">General</th></tr><tr><th scope="row" class="infobox-label"><a href="/wiki/Table_of_nuclides" title="Table of nuclides">Symbol</a></th><td class="infobox-data"><sup>222</sup>Rn</td></tr><tr><th scope="row" class="infobox-label"><a href="/wiki/List_of_nuclides" title="List of nuclides">Names</a></th><td class="infobox-data">radon-222, 222Rn, Rn-222,<br />Radium emanation</td></tr><tr><th scope="row" class="infobox-label"><a href="/wiki/Atomic_number" title="Atomic number">Protons</a> <style data-mw-deduplicate="TemplateStyles:r886047488">.mw-parser-output .nobold{font-weight:normal}</style><span class="nobold">(<i>Z</i>)</span></th><td class="infobox-data">86</td></tr><tr><th scope="row" class="infobox-label"><a href="/wiki/Neutron_number" title="Neutron number">Neutrons</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886047488" /><span class="nobold">(<i>N</i>)</span></th><td class="infobox-data">136</td></tr><tr><th colspan="2" class="infobox-header" style="background:#eee"><a href="/wiki/Table_of_nuclides" title="Table of nuclides">Nuclide data</a></th></tr><tr><th scope="row" class="infobox-label"><a href="/wiki/Natural_abundance" title="Natural abundance">Natural abundance</a></th><td class="infobox-data"><a href="/wiki/Trace_radioisotope" title="Trace radioisotope">Trace</a></td></tr><tr><th scope="row" class="infobox-label"><a href="/wiki/Half-life" title="Half-life">Half-life</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886047488" /><span class="nobold">(<i>t</i><sub>1/2</sub>)</span></th><td class="infobox-data"><span class="nowrap"><span data-sort-value="7005330177600000000♠"></span>3.8215(2) d</span><sup id="cite_ref-NUBASE2020_1-0" class="reference"><a href="#cite_note-NUBASE2020-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup></td></tr><tr><th scope="row" class="infobox-label"><a href="/wiki/Atomic_mass" title="Atomic mass">Isotope mass</a></th><td class="infobox-data">222.0175760(21)<sup id="cite_ref-AME2020_II_2-0" class="reference"><a href="#cite_note-AME2020_II-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> <a href="/wiki/Dalton_(unit)" title="Dalton (unit)">Da</a></td></tr><tr><th scope="row" class="infobox-label"><a href="/wiki/Spin_(particle_physics)" class="mw-redirect" title="Spin (particle physics)">Spin</a></th><td class="infobox-data">0</td></tr><tr><th scope="row" class="infobox-label"><a href="/wiki/Parent_isotope" class="mw-redirect" title="Parent isotope">Parent isotopes</a></th><td class="infobox-data"><a href="/wiki/Radium-226" title="Radium-226"><sup>226</sup>Ra</a> (<a href="/wiki/Alpha_decay" title="Alpha decay">α</a>)</td></tr><tr><th scope="row" class="infobox-label"><a href="/wiki/Decay_product" title="Decay product">Decay products</a></th><td class="infobox-data"><a href="/wiki/Polonium-218" class="mw-redirect" title="Polonium-218"><sup>218</sup>Po</a></td></tr><tr><th colspan="2" class="infobox-header" style="background:#eee">Decay modes</th></tr><tr style="font-weight:bold"><th scope="row" class="infobox-label"><a href="/wiki/Decay_mode" class="mw-redirect" title="Decay mode">Decay mode</a></th><td class="infobox-data"><a href="/wiki/Decay_energy" title="Decay energy">Decay energy</a> (<a href="/wiki/Electronvolt" title="Electronvolt">MeV</a>)</td></tr><tr><th scope="row" class="infobox-label"><span style="font-weight:normal"><a href="/wiki/Alpha_decay" title="Alpha decay">Alpha decay</a></span></th><td class="infobox-data">5.5904(3)<sup id="cite_ref-AME2020_II_2-1" class="reference"><a href="#cite_note-AME2020_II-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup></td></tr><tr><td colspan="2" class="infobox-below" style="background:#eee"><a href="/wiki/Isotopes_of_radon" title="Isotopes of radon">Isotopes of radon</a> <br /><a href="/wiki/Table_of_nuclides" title="Table of nuclides">Complete table of nuclides</a></td></tr></tbody></table> <p><b>Radon-222</b> (<sup>222</sup>Rn, Rn-222, historically <b>radium emanation</b> or radon) is the most stable <a href="/wiki/Isotope" title="Isotope">isotope</a> of <a href="/wiki/Radon" title="Radon">radon</a>, with a <a href="/wiki/Half-life" title="Half-life">half-life</a> of approximately 3.8215(2) days<sup id="cite_ref-NUBASE2020_1-1" class="reference"><a href="#cite_note-NUBASE2020-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup>. It is transient in the <a href="/wiki/Decay_chain" title="Decay chain">decay chain</a> of <a href="/wiki/Primordial_radionuclide" class="mw-redirect" title="Primordial radionuclide">primordial</a> <a href="/wiki/Uranium-238" title="Uranium-238">uranium-238</a> and is the immediate decay product of <a href="/wiki/Radium-226" title="Radium-226">radium-226</a>. Radon-222 was first observed in 1899, and was identified as an isotope of a new <a href="/wiki/Chemical_element" title="Chemical element">element</a> several years later. In 1957, the name <i>radon</i>, formerly the name of only radon-222, became the name of the element. Owing to its gaseous nature and high radioactivity, radon-222 is one of the leading causes of <a href="/wiki/Lung_cancer" title="Lung cancer">lung cancer</a>.<sup id="cite_ref-EPA02_3-0" class="reference"><a href="#cite_note-EPA02-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="History">History</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Radon-222&action=edit&section=1" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Following the 1898 discovery of <a href="/wiki/Radium" title="Radium">radium</a> through chemical analysis of <a href="/wiki/Radioactive" class="mw-redirect" title="Radioactive">radioactive</a> ore, <a href="/wiki/Marie_Curie" title="Marie Curie">Marie</a> and <a href="/wiki/Pierre_Curie" title="Pierre Curie">Pierre Curie</a> observed a new radioactive substance emanating from radium in 1899 that was strongly radioactive for several days.<sup id="cite_ref-RnIsotopes_4-0" class="reference"><a href="#cite_note-RnIsotopes-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> Around the same time, <a href="/wiki/Ernest_Rutherford" title="Ernest Rutherford">Ernest Rutherford</a> and <a href="/wiki/Robert_B._Owens" class="mw-redirect" title="Robert B. Owens">Robert B. Owens</a> observed a similar (though shorter-lived) emission from <a href="/wiki/Thorium" title="Thorium">thorium</a> compounds.<sup id="cite_ref-isodiscovery_5-0" class="reference"><a href="#cite_note-isodiscovery-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> German physicist <a href="/wiki/Friedrich_Ernst_Dorn" title="Friedrich Ernst Dorn">Friedrich Ernst Dorn</a> extensively studied these emanations in the early 1900s and attributed them to a new gaseous element, radon. In particular, he studied the product in the <a href="/wiki/Uranium_series" class="mw-redirect" title="Uranium series">uranium series</a>, radon-222, which he called <i>radium emanation</i>.<sup id="cite_ref-george_6-0" class="reference"><a href="#cite_note-george-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p><p>In the early 20th century, the element radon was known by several different names. Chemist <a href="/wiki/William_Ramsay" title="William Ramsay">William Ramsay</a>, who extensively studied the element's chemical properties, suggested the name <i>niton</i>, and Rutherford originally suggested <i>emanation</i>. At that time, <i>radon</i> only referred to the isotope <sup>222</sup>Rn, whereas the names <i>actinon</i> and <i>thoron</i> denoted <sup>219</sup>Rn and <sup>220</sup>Rn, respectively.<sup id="cite_ref-RnNatureChem_7-0" class="reference"><a href="#cite_note-RnNatureChem-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> In 1957, the <a href="/wiki/International_Union_of_Pure_and_Applied_Chemistry" title="International Union of Pure and Applied Chemistry">International Union of Pure and Applied Chemistry</a> (IUPAC) promoted the name <i>radon</i> to refer to the element rather than just <sup>222</sup>Rn; this was done under a new rule concerning isotope naming conventions.<sup id="cite_ref-RnNatureChem_7-1" class="reference"><a href="#cite_note-RnNatureChem-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> This decision was controversial because it was believed to give undue credit to Dorn's identification of radon-222 over Rutherford's identification of radon-220, and the historical use of the name radon created confusion as to whether the element or the isotope <sup>222</sup>Rn was being discussed.<sup id="cite_ref-RnNatureChem_7-2" class="reference"><a href="#cite_note-RnNatureChem-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Decay_properties">Decay properties</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Radon-222&action=edit&section=2" title="Edit section: Decay properties"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Decay_chain(4n%2B2,_Uranium_series).PNG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a1/Decay_chain%284n%2B2%2C_Uranium_series%29.PNG/240px-Decay_chain%284n%2B2%2C_Uranium_series%29.PNG" decoding="async" width="240" height="314" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a1/Decay_chain%284n%2B2%2C_Uranium_series%29.PNG/360px-Decay_chain%284n%2B2%2C_Uranium_series%29.PNG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a1/Decay_chain%284n%2B2%2C_Uranium_series%29.PNG/480px-Decay_chain%284n%2B2%2C_Uranium_series%29.PNG 2x" data-file-width="1100" data-file-height="1440" /></a><figcaption>The decay chain of uranium-238, known as the uranium series or radium series, of which radon-222 is a member.</figcaption></figure> <p>Radon-222 is generated in the uranium series from the <a href="/wiki/Alpha_decay" title="Alpha decay">alpha decay</a> of radium-226, which has a half-life of 1600 years. Radon-222 itself alpha decays to <a href="/wiki/Polonium-218" class="mw-redirect" title="Polonium-218">polonium-218</a> with a half-life of approximately 3.82 days, making it the most stable isotope of radon.<sup id="cite_ref-NUBASE2020_1-2" class="reference"><a href="#cite_note-NUBASE2020-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> Its final decay product is stable <a href="/wiki/Lead-206" class="mw-redirect" title="Lead-206">lead-206</a>. </p><p>In theory, <sup>222</sup>Rn is capable of <a href="/wiki/Double_beta_decay" title="Double beta decay">double beta decay</a> to <sup>222</sup>Ra, and depending on the mass measurement, single <a href="/wiki/Beta_decay" title="Beta decay">beta decay</a> to <sup>222</sup>Fr may also be allowed.<sup id="cite_ref-BelliBaF2_8-0" class="reference"><a href="#cite_note-BelliBaF2-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>a<span class="cite-bracket">]</span></a></sup> These decay modes have been searched for, yielding lower <a href="/wiki/Partial_half-life" class="mw-redirect" title="Partial half-life">partial half-life</a> limits of 8 years for both transitions. If the beta decay of <sup>222</sup>Rn is possible, it is predicted to have a very low decay energy (24 ± 21 <a href="/wiki/Electronvolt" title="Electronvolt">keV</a>) and thus a half-life on the order of 10<sup>5</sup> years, also resulting in a very low branching probability relative to alpha decay.<sup id="cite_ref-BelliBaF2_8-1" class="reference"><a href="#cite_note-BelliBaF2-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> The last edition of Atomic Mass Evaluation<sup id="cite_ref-AME2020_II_2-3" class="reference"><a href="#cite_note-AME2020_II-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> gives even lower value of the decay energy <span class="nowrap">(−6 ± 8) keV</span>; thus the single beta decay is, probably, forbidden kinematically. </p> <div class="mw-heading mw-heading2"><h2 id="Occurrence_and_hazards">Occurrence and hazards</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Radon-222&action=edit&section=3" title="Edit section: Occurrence and hazards"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Health_effects_of_radon" title="Health effects of radon">Health effects of radon</a></div> <p>All radon isotopes are hazardous owing to their radioactivity, gaseous nature, chemical inertness, and radioactivity of their decay products (progeny). Radon-222 is especially dangerous because its longer half-life allows it to permeate soil and rocks, where it is produced in trace quantities from decays of uranium-238, and concentrate in buildings and <a href="/wiki/Uranium_mining#Health_risks" title="Uranium mining">uranium mines</a>. This contrasts with the other natural isotopes that decay far more quickly (half-lives less than 1 minute) and thus do not contribute significantly to radiation exposure.<sup id="cite_ref-EPA01_10-0" class="reference"><a href="#cite_note-EPA01-10"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> At higher concentrations, gaseous <sup>222</sup>Rn may be inhaled and decay before exhalation, which leads to a buildup of its daughters <sup>218</sup>Po and <sup>214</sup>Po in the lungs, whose high-energy alpha and <a href="/wiki/Gamma_radiation" class="mw-redirect" title="Gamma radiation">gamma</a> radiation damages cells. Extended periods of exposure to <sup>222</sup>Rn and its progeny ultimately induce lung cancer.<sup id="cite_ref-EPA01_10-1" class="reference"><a href="#cite_note-EPA01-10"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> Alternatively, radon may enter the body through contaminated drinking water or through the decay of ingested radium<sup id="cite_ref-EPA02_3-1" class="reference"><a href="#cite_note-EPA02-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> – making radon diffusion one of the greatest dangers of radium.<sup id="cite_ref-EPA03_11-0" class="reference"><a href="#cite_note-EPA03-11"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> Thus, <sup>222</sup>Rn is a <a href="/wiki/Carcinogen" title="Carcinogen">carcinogen</a>; in fact, it is the second leading cause of lung cancer in the <a href="/wiki/United_States" title="United States">United States</a> after <a href="/wiki/Cigarette_smoking" class="mw-redirect" title="Cigarette smoking">cigarette smoking</a>,<sup id="cite_ref-EPA02_3-2" class="reference"><a href="#cite_note-EPA02-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> with over 20,000 deaths per year attributed to radon-induced lung cancer.<sup id="cite_ref-EPA01_10-2" class="reference"><a href="#cite_note-EPA01-10"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-factsheet_12-0" class="reference"><a href="#cite_note-factsheet-12"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Radon-222&action=edit&section=4" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Isotopes_of_radon" title="Isotopes of radon">Isotopes of radon</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="Notes">Notes</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Radon-222&action=edit&section=5" title="Edit section: Notes"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-lower-alpha"> <div class="mw-references-wrap"><ol class="references"> <li id="cite_note-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-9">^</a></b></span> <span class="reference-text">AME2020 gives <sup>222</sup>Rn a lower mass than <sup>222</sup>Fr (the available energy is <span class="nowrap">(−6 ± 8) keV</span>),<sup id="cite_ref-NUBASE2020_1-3" class="reference"><a href="#cite_note-NUBASE2020-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-AME2020_II_2-2" class="reference"><a href="#cite_note-AME2020_II-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> which would forbid single beta decay, though it is possible within the given error margin and is explicitly predicted by Belli et al.</span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Radon-222&action=edit&section=6" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239543626" /><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-NUBASE2020-1"><span class="mw-cite-backlink">^ <a href="#cite_ref-NUBASE2020_1-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NUBASE2020_1-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-NUBASE2020_1-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-NUBASE2020_1-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFKondevWangHuangNaimi2021" class="citation journal cs1">Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). <a rel="nofollow" class="external text" href="https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf">"The NUBASE2020 evaluation of nuclear properties"</a> <span class="cs1-format">(PDF)</span>. <i>Chinese Physics C</i>. <b>45</b> (3): 030001. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1088%2F1674-1137%2Fabddae">10.1088/1674-1137/abddae</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Chinese+Physics+C&rft.atitle=The+NUBASE2020+evaluation+of+nuclear+properties&rft.volume=45&rft.issue=3&rft.pages=030001&rft.date=2021&rft_id=info%3Adoi%2F10.1088%2F1674-1137%2Fabddae&rft.aulast=Kondev&rft.aufirst=F.+G.&rft.au=Wang%2C+M.&rft.au=Huang%2C+W.+J.&rft.au=Naimi%2C+S.&rft.au=Audi%2C+G.&rft_id=https%3A%2F%2Fwww-nds.iaea.org%2Famdc%2Fame2020%2FNUBASE2020.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ARadon-222" class="Z3988"></span> </span> </li> <li id="cite_note-AME2020_II-2"><span class="mw-cite-backlink">^ <a href="#cite_ref-AME2020_II_2-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-AME2020_II_2-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-AME2020_II_2-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-AME2020_II_2-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFWangHuangKondevAudi2021" class="citation journal cs1">Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. 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Tables, graphs and references". <i>Chinese Physics C</i>. <b>45</b> (3): 030003. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1088%2F1674-1137%2Fabddaf">10.1088/1674-1137/abddaf</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Chinese+Physics+C&rft.atitle=The+AME+2020+atomic+mass+evaluation+%28II%29.+Tables%2C+graphs+and+references&rft.volume=45&rft.issue=3&rft.pages=030003&rft.date=2021&rft_id=info%3Adoi%2F10.1088%2F1674-1137%2Fabddaf&rft.aulast=Wang&rft.aufirst=Meng&rft.au=Huang%2C+W.J.&rft.au=Kondev%2C+F.G.&rft.au=Audi%2C+G.&rft.au=Naimi%2C+S.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ARadon-222" class="Z3988"></span> </span> </li> <li id="cite_note-EPA02-3"><span class="mw-cite-backlink">^ <a href="#cite_ref-EPA02_3-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-EPA02_3-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-EPA02_3-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite class="citation report cs1"><a rel="nofollow" class="external text" href="https://semspub.epa.gov/work/11/176336.pdf">EPA Facts about Radon</a> <span class="cs1-format">(PDF)</span> (Report). 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