Isotopes of cerium

Naturally occurring cerium (Ce) is composed of 3 stable isotopes and 1 radioactive isotope; 136Ce, 138Ce, 140Ce, and 142Ce with 140Ce being the most abundant (88.48% natural abundance). 27 radioisotopes have been characterized with the most {abundant and/or stable} being 142Ce with a half-life of greater than 5&times;1016 years, 144Ce with a half-life of 284.893 days, 139Ce with a half-life of 137.640 days, and 141Ce with a half-life of 32.501 days. All of the remaining radioactive isotopes have half-lives that are less than 4 days and the majority of these have half-lives that are less than 10 minutes. This element also has 2 meta states.

The isotopes of cerium range in atomic weight from 123 u (123Ce) to 152 u (152Ce).

Standard atomic mass: 140.116(1) u