Technetium: Difference between revisions - Wikipedia
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Line 163: ==Occurrence and production== Technetium occurs naturally in the Earth's [[Crust (geology)|crust]] in minute concentrations of about 0.003 parts per trillion. Technetium is so rare because the [[half-life|half-lives]] of <sup>97</sup>Tc and <sup>98</sup>Tc are only 4.2 million years. More than a thousand of such periods have passed since the formation of the [[Earth]], so the probability of survival of even one atom of [[primordial nuclide|primordial]] technetium is effectively zero. However, small amounts exist as spontaneous [[fission product]]s in [[uranium ore]]s. A kilogram of uranium contains an estimated 1 [[Orders of magnitude (mass)|nanogram]] (10<sup>−9</sup> g) equivalent to ten trillion atoms of technetium.<ref name="blocks" /><ref>{{cite journal|doi=10.1021/ac961159q |title=Analysis of Naturally Produced Technetium and Plutonium in Geologic Materials|date=1997 |last1=Dixon|first1=P.|last2=Curtis|first2=David B. |last3=Musgrave|first3=John |last4=Roensch|first4=Fred|last5=Roach|first5=Jeff|last6=Rokop|first6=Don|journal=Analytical Chemistry |volume=69|issue=9|pages=1692–1699|pmid=21639292}}</ref><ref>{{cite journal |doi=10.1016/S0016-7037(98)00282-8 |title=Nature's uncommon elements: plutonium and technetium|last1=Curtis|first1=D. |last2=Fabryka-Martin|first2=June|last3=Dixon|first3=Paul|last4=Cramer|first4=Jan|date=1999 |journal=Geochimica et Cosmochimica Acta |volume=63|issue=2|pages=275|bibcode=1999GeCoA..63..275C |url=https://digital.library.unt.edu/ark:/67531/metadc704244/}}</ref> Some [[red giant]] stars with the spectral types S-, M-, and N ===Fission waste product=== | |||