Editing Chalcogen (section)

===Isotopes===
Out of the six known chalcogens, one (oxygen) has an atomic number equal to a nuclear [[Magic number (physics)|magic number]], which means that their [[atomic nuclei]] tend to have increased stability against radioactive decay.<ref name="The Disappearing Spoon"/> Oxygen has three stable isotopes, and 14 unstable ones. Sulfur has four stable isotopes, 20 radioactive ones, and one [[nuclear isomer|isomer]]. Selenium has six [[observationally stable]] or nearly stable isotopes, 26 radioactive isotopes, and 9 isomers. Tellurium has eight stable or nearly stable isotopes, 31 unstable ones, and 17 isomers. Polonium has 42 isotopes, none of which are stable.<ref>{{cite web|last = Sonzogniurl|first = Alejandro|url = http://www.nndc.bnl.gov/nudat2/reCenter.jsp?z=84&n=130|title = Double Beta Decay for Selenium-82|access-date = November 25, 2013|publisher = Brookhaven National Laboratory|archive-date = October 3, 2021|archive-url = https://web.archive.org/web/20211003183335/https://www.nndc.bnl.gov/nudat2/reCenter.jsp?z=84&n=130|url-status = dead}}</ref> It has an additional 28 isomers.<ref name="ReferenceB"/> In addition to the stable isotopes, some radioactive chalcogen isotopes occur in nature, either because they are decay products, such as [[polonium-210|<sup>210</sup>Po]], because they are [[primordial nuclide|primordial]], such as <sup>82</sup>Se, because of [[cosmic ray]] [[spallation]], or via [[nuclear fission]] of uranium. Livermorium isotopes <sup>288</sup>Lv through <sup>293</sup>Lv have been discovered; the most stable livermorium isotope is <sup>293</sup>Lv, which has a half-life of 0.061 seconds.<ref name = "ReferenceB"/><ref>{{cite journal|year = 1973|title = Double Beta Decay of Selenium-82|doi = 10.2113/gsecongeo.68.2.252|journal = Economic Geology|volume = 68|issue = 2|page = 252|last1 = Srinivasan|first1 = B.|last2 = Alexander|first2 = E. C.|last3 = Beaty|first3 = R. D.|last4 = Sinclair|first4 = D. E.|last5 = Manuel|first5 = O. K.| bibcode=1973EcGeo..68..252S }}</ref>

With the exception of livermorium, all chalcogens have at least one naturally occurring [[radioisotope]]: oxygen has trace <sup>15</sup>O, sulfur has trace <sup>35</sup>S, selenium has <sup>82</sup>Se, tellurium has <sup>128</sup>Te and <sup>130</sup>Te, and polonium has <sup>210</sup>Po.

Among the lighter chalcogens (oxygen and sulfur), the most neutron-poor isotopes undergo [[proton emission]], the moderately neutron-poor isotopes undergo [[electron capture]] or [[beta plus decay|β<sup>+</sup> decay]], the moderately neutron-rich isotopes undergo [[beta decay|β<sup>−</sup> decay]], and the most neutron rich isotopes undergo [[neutron emission]]. The middle chalcogens (selenium and tellurium) have similar decay tendencies as the lighter chalcogens, but no proton-emitting isotopes have been observed, and some of the most neutron-deficient isotopes of tellurium undergo [[alpha decay]]. Polonium isotopes tend to decay via alpha or beta decay.<ref>{{cite web |url=http://www.nndc.bnl.gov/nudat2/reCenter.jsp?z=47&n=63 |title=Nudat 2 |publisher=Nndc.bnl.gov |access-date=November 25, 2013 |archive-date=July 14, 2017 |archive-url=https://web.archive.org/web/20170714190234/http://www.nndc.bnl.gov/nudat2/reCenter.jsp?z=47&n=63 |url-status=dead }}</ref> Isotopes with nonzero [[nuclear spin]]s are more abundant in nature among the chalcogens selenium and tellurium than they are with sulfur.<ref name="synth"/>