![]() ![]() The primary decay mode before the second most abundant stable isotope, 112Cd, is electron capture and the primary modes after are beta emission and electron capture. The known isotopes of cadmium range in atomic mass from 94.950 u ( 95Cd) to 131.946 u ( 132Cd). ![]() This element also has 12 known meta states, with the most stable being 113mCd (t 1/2 14.1 years), 115mCd (t 1/2 44.6 days) and 117mCd (t 1/2 3.36 hours). All of the remaining radioactive isotopes have half-lives that are less than 2.5 hours and the majority of these have half-lives that are less than 5 minutes. Among the isotopes absent in natural cadmium, the most long-lived are 109Cd with a half-life of 462.6 days, and 115Cd with a half-life of 53.46 hours. At least three isotopes- 110Cd, 111Cd, and 112Cd-are absolutely stable (except, theoretically, to spontaneous fission). The other three are 106Cd, 108Cd ( double electron capture), and 114Cd (double beta decay) only lower limits on their half-life times have been set. The two natural radioactive isotopes are 113Cd ( beta decay, half-life is 8.04 × 10 15 years) and 116Cd (two-neutrino double beta decay, half-life is 2.8 × 10 19 years). For two of them, natural radioactivity was observed, and three others are predicted to be radioactive but their decays have not been observed, due to extremely long half-lives. Naturally occurring cadmium ( 48Cd) is composed of 8 isotopes. ![]()
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