The Elements (07Nov00):

americium
Symbol: Am
Atomic number: 95
Atomic weight: (243)
Radioactive metallic transuranic element, belongs to the actinoids. Ten
known isotopes. Am-243 is the most stable isotope, with a half-life of
7.95*10^3 years. Discovered by Glenn T. Seaborg and associates in 1945,
it
was obtained by bombarding uranium-238 with alpha particles.