Editing Synthetic element (section)

===Technetium===
The first element to be synthesized, rather than discovered in nature, was [[technetium]] in 1937.<ref>{{cite web |last1=Helmenstine |first1=Anne Marie |title=Technetium or Masurium Facts |url=https://www.thoughtco.com/technetium-or-masurium-facts-606601 |publisher=ThoughtCo |access-date=15 May 2019}}</ref> This discovery filled a gap in the [[periodic table]], and the fact that technetium has no [[stable isotope]]s explains its natural absence on Earth (and the gap).<ref>{{cite web |title=Technetium decay and its cardiac application |url=https://www.khanacademy.org/test-prep/mcat/physical-sciences-practice/physical-sciences-practice-tut/e/cs-passage-4  |publisher=Khan Academy |access-date=15 May 2019}}</ref> With the longest-lived isotope of technetium, <sup>97</sup>Tc, having a [[1e14 s|4.21-million-year]] half-life,{{NUBASE2020|ref}} no technetium remains from the formation of the Earth.<ref>{{cite web |last1=Stewart |first1=Doug |title=Technetium Element Facts |url=https://www.chemicool.com/elements/technetium.html |website=Chemicool |access-date=15 May 2019}}</ref><ref>{{cite web |last1=Bentor |first1=Yinon |title=Periodic Table: Technetium |url=http://www.chemicalelements.com/elements/tc.html |website=Chemical Elements |access-date=15 May 2019}}</ref> Only minute traces of technetium occur naturally in Earth's crust—as a [[fission product|product]] of [[spontaneous fission]] of <sup>238</sup>U, or from [[neutron capture]] in [[molybdenum]]—but technetium is present naturally in [[red giant]] stars.<ref name=CRC>{{cite book |first = C. R. |last = Hammond |chapter = The Elements |title = Handbook of Chemistry and Physics |edition = 81st |publisher = CRC press |isbn = 978-0-8493-0485-9 |date = 2004 |url-access = registration |url = https://archive.org/details/crchandbookofche81lide }}</ref><ref>{{cite journal|doi = 10.1126/science.114.2951.59|pmid = 17782983|date = 1951|last1 = Moore|first1 = C. E.|title = Technetium in the Sun|volume = 114|issue = 2951|pages = 59–61|journal = Science |bibcode=1951Sci...114...59M}}</ref><ref>{{cite journal|doi = 10.1021/ac961159q|title = Analysis of Naturally Produced Technetium and Plutonium in Geologic Materials|date = 1997|last1 = Dixon|first1 = P.|journal = Analytical Chemistry|volume = 69|pages = 1692–9|last2 = Curtis|first2 = David B.|last3 = Musgrave|first3 = John|last4 = Roensch|first4 = Fred|last5 = Roach|first5 = Jeff|last6 = Rokop|first6 = Don|issue = 9|pmid = 21639292}}</ref><ref>{{cite journal|doi =10.1016/S0016-7037(98)00282-8|title =Nature's uncommon elements: plutonium and technetium|first4 =Jan|last4 =Cramer|first3 =Paul|last3 =Dixon|first2 =June|date=1999|last2 =Fabryka-Martin|last1=Curtis|first1=D.|journal=Geochimica et Cosmochimica Acta|volume =63|pages =275|bibcode=1999GeCoA..63..275C|issue =2|url =https://digital.library.unt.edu/ark:/67531/metadc704244/}}</ref>