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Definition: fermium from Philip's Encyclopedia

(symbol Fm) Radioactive metallic transuranic element of the actinide series. US nuclear scientist Albert Ghiorso (1915- ) and colleagues identified it in 1952 as a decay product of U255 from the first large hydrogen bomb explosion. Ten isotopes have subsequently been identified. Properties: at.no. 100; most stable isotope Fm257 (half-life 80 days).


Summary Article: fermium from The Columbia Encyclopedia

(fûr'mēəm) [for Enrico Fermi], artificially produced radioactive chemical element; symbol Fm; at. no. 100; mass no. of most stable isotope 257; m.p. 1,527 degrees Celsius; b.p. and sp. gr. unknown; valence +2, +3. Fermium is a member of Group 3 of the periodic table. The physical properties of fermium are largely unknown; its chemical properties are believed to be similar to those of the other members of the actinide series. The eighth transuranium element to be discovered, fermium was first identified (1952) as fermium-255 (half-life about 20 hours) by Albert Ghiorso and his coworkers, who discovered it in residue from the first thermonuclear test explosion in the South Pacific. Twenty isotopes, all of which are radioactive, are known; the most stable is fermium-257, with a half-life of 100.5 days. Isotopes of fermium have been produced by neutron bombardment of plutonium.

The Columbia Encyclopedia, © Columbia University Press 2017

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