Curium, a radioactive metallic chemical element. Curium does not occur in nature; it is produced artificially. Its most stable isotope is curium 247, which has a half-life of 16 million years. The radioactivity of curium is utilized as a source of heat for producing electricity to operate instruments in space vehicles and in remote locations on earth.

Curium was first produced in 1944 by Glenn T. Seaborg, Ralph A. James, and Albert Ghiorso by bombarding plutonium with alpha particles in a cyclotron. It was named in honor of Pierre and Marie Curie.

Symbol: Cm. Atomic number: 96 Atomic weight: 247. Curium has 13 known isotopes: Cm-238 through Cm-250. Melting point: 2,440 F. (1,340 C.). Curium is a transuranium element belonging to the actinide series of the Periodic Table and has a valence of +3.