Article
Article
Actinium
Article By:
Fried, Sherman Chemistry Division, Argonne National Laboratory, Argonne, Illinois.
Last reviewed:August 2019
DOI:https://doi.org/10.1036/1097-8542.008200
A chemical element, Ac, atomic number 89, and atomic weight 227.0. Actinium was discovered by A. Debierne in 1899. Milligram quantities of the element are available by irradiation of radium in a nuclear reactor. Actinium-227 is a beta-emitting element whose half-life is 22 years. Six other radioisotopes with half-lives ranging from 10 days to less than 1 minute have been identified.
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