thorium

tho·ri·um  (thôr-m, thr-)

n. Symbol Th

A radioactive silvery-white metallic element that is recovered commercially from monazite. Its longest-lived isotope, the only one that occurs naturally, is Th 232 with a half-life of 1.41 × 10¹⁰ years. It is used in magnesium alloys, and isotope 232 is a source of nuclear energy. Atomic number 90; atomic weight 232.038; approximate melting point 1,750°C; approximate boiling point 4,500°C; approximate specific gravity 11.7; valence 4. See Table at element.

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[After Thor.]

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thorium

Noun

Chem a silvery-white radioactive metallic element. It is used in electronic equipment and as a nuclear power source Symbol: Th[after Thor, Norse god of thunder]

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thorium  (thôr-m)

Symbol Th

A silvery-white, radioactive metallic element of the actinide series. It is used for fuel in some nuclear reactors and for improving the high-temperature strength of magnesium alloys. The only naturally occurring isotope of thorium, Th 232, is also its most stable, having a half-life of 14.1 billion years. Atomic number 90; atomic weight 232.038; approximate melting point 1,750°C; approximate boiling point 4,500°C; approximate specific gravity 11.7; valence 4. See Periodic Table.

Thesaurus

Noun

1.

thorium - a soft silvery-white tetravalent radioactive metallic element; isotope 232 is used as a power source in nuclear reactors; occurs in thorite and in monazite sands atomic number 90, Th metal, metallic element - any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc. radiothorium, thorium-228 - radioactive isotope of thorium with mass number 228 monazite - a reddish-brown mineral containing rare earth metals; an important source of thorium and cerium thorite - a radioactive mineral consisting of thorium silicate; it is a source of thorium that is found in coarse granite