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

Example Sentences

There are already two different drug injections that can be used to treat people who have been exposed to radioactive plutonium, americium or curium.

From BBC

The most stable isotopes of americium and curium decay faster than uranium’s most stable isotopes.

From Scientific American

Two of nuclear waste’s most problematic ingredients are metals called americium and curium; each has particularly long-lived forms that decay slowly over thousands of years.

From Scientific American

The waste includes isotopes of iodine, strontium, americium, plutonium, uranium and other unstable elements, many of which are toxic as well as radioactive.

From Los Angeles Times

Inhalation of the particles, which included uranium, thorium, plutonium and americium, can increase the risk of cancer.

From Seattle Times