americium

[ am-uh-rish-ee-uhm ]

noun

, Chemistry.

1. a transuranic element, one of the products of high-energy helium bombardment of uranium and plutonium. : Am; : 95.

americium

/ ˌæməˈrɪsɪəm /

noun

1. a white metallic transuranic element artificially produced from plutonium. It is used as an alpha-particle source. Symbol: Am; atomic no: 95; half-life of most stable isotope, ²⁴³Am: 7.4 × 10³ years; valency: 2,3,4,5, or 6; relative density: 13.67; melting pt: 1176°C; boiling pt: 2607°C (est)

americium

/ ăm′ə-rĭsh′ē-əm /

1. Symbol Am A synthetic, silvery-white, radioactive metallic element of the actinide series that is produced artificially by bombarding plutonium with neutrons. Americium is used as a source of alpha particles for smoke detectors and gamma rays for industrial gauges. Its most stable isotope has a half-life of 7,950 years. Atomic number 95; specific gravity 11.7; valence 3, 4, 5, 6.
2. See Periodic Table

Word History and Origins

Origin of americium¹

An Americanism dating back to 1945–50; Americ(a) + -ium

Word History and Origins

Origin of americium¹

C20: from America (because it was discovered at Berkeley, California) + -ium