(So named (America + -ium) by Glenn T. Seaborg, one of its discovers, by analogy with europium, the corresponding rare-earth metal) A radioactive, metallic chemical element, one of the actinides, produced by the beta decay of an isotope of plutonium. It is used in smoke detectors.

Symbol: Am
Atomic number: 95
Atomic weight: 243 (isotope with the longest known half-life)
Density (at room temperature and pressure): 13.67 g/cc
Melting point: 1,176°C
Boiling point: 2,607°C
Ground state electron configuration: [Rn]5f77s9