Americium

Americium, chemical element, symbol Am; for physical constants see Periodic Table. Americium was synthesized by Glenn Seaborg and co-workers in 1944 by bombardment of plutonium-234 with alpha particles at the wartime Metallurgical Laboratory of the University of Chicago (now the Argonne National Laboratory). It is produced in quantity by neutron irradiation of plutonium isotopes in a nuclear reactor. Americium is a reactive, radioactive, metal, obtained by reducing its trifluoride with barium vapor. It is a member of the actinide series. The element must be handled with special care because of its great alpha and gamma activity. Americium is used in gamma radiography, glass thickness gages, and in smoke detectors. Thirteen isotopes of americium are known.