promethium

(prō mēt̸hē əm)

noun

a radioactive chemical element, one of the rare-earth elements, obtained from fission of uranium or neutron bombardment of neodymium and used in phosphorescent paint, as a power source, X-ray source, etc.: symbol, Pm; at. no., 61

Origin: ModL: so named (1949) for earlier prometheum, name proposed by G. M. Coryell for element isolated (1948) by J. A. Marinsky & L. E. Glendenin, U.S. physicists < Gr Promētheus (see Prometheus) in reference to production by nuclear fission + -ium

See promethium in American Heritage Dictionary 4

noun Symbol Pm
A radioactive rare-earth element prepared by fission of uranium or by neutron bombardment of neodymium, having 14 isotopes with mass numbers ranging from 141 to 154 and used as a source of beta rays. Atomic number 61; melting point 1,168°C; boiling point 2,460°C; valence 3. See Table at element.

Origin:

Origin: From Prometheus

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