Isotopes of cobalt

Naturally occurring cobalt, Co, consists of a single stable isotope, Co (thus, cobalt is a mononuclidic element). Twenty-eight radioisotopes have been characterized; the most stable are Co with a half-life of 5.2714 years, Co (271.81 days), Co (77.24 days), and Co (70.84 days). All other isotopes have half-lives of less than 18 hours and most of these have half-lives of less than 1 second. This element also has 19 meta states, of which the most stable is Co with a half-life of 8.85 hours.

The isotopes of cobalt range in atomic weight from Co to Co. The main decay mode for isotopes with atomic mass less than that of the stable isotope, Co, is electron capture to iron isotopes, and the main mode of decay for those with greater mass is beta decay to nickel isotopes.