A radioactive metallic transuranic element belonging to the actinoids; a.n. 97; mass number of the most stable isotope 247 (half-life 1.4 × 103 years); r.d. (calculated) 14. There are eight known isotopes. It was first produced by Glenn Seborg and associates in 1949 by bombarding americium–241 with alpha particles.
https://www.webelements.com/berkelium/ Information from the WebElements site