berkelium

noun

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

Etymology: ModL, after Berkeley, Calif. + -ium: so named by Glenn T. Seaborg, U.S. chemist and one of its discoverers, by analogy with terbium