a radioactive, metallic chemical element, one of the actinides, initially produced by bombarding americium with high-energy alpha particles in a cyclotron, and now prepared by intense neutron bombardment of plutonium: symbol, Bk; at. no., 97
See berkelium in American Heritage Dictionary 4
(bər-kēˈlē-əm, bûrkˈlē-əm)
noun Symbol Bk
A synthetic transuranic radioactive element having 9 isotopes with mass numbers from 243 to 250 and half-lives from 3 hours to 1,380 years. Atomic number 97; melting point 986°C; valence 3, 4. See Table at element.