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 14.1 billion years and is used as a nuclear fuel. Thorium is used in magnesium alloys, and its oxide is widely used in gas mantles of Welsbach burners. Atomic number 90; atomic weight 232.038; melting point 1,750°C; boiling point 4,788°C; specific gravity 11.72; valence 4.
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A rare, grayish, radioactive, metallic chemical element, one of the actinides, found in monazite and thorite: it is used in magnesium alloys, the making of gas mantles, electronic equipment, etc., and as a nuclear fuel: symbol, Th; at. no. 90
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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.
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A chemical element (symbol Th) with atomic number 90.
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(physics) A radioactiveisotope of thorium, 22890Th, having a half-life of 1.4 x 1010 years; it occurs naturally, and is a source of nuclear energy.
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Origin of thorium
After Thor
From
American Heritage Dictionary of the English Language, 5th Edition
With Three Hours' Exposure He Found The Thorium Emanation Only From 3 To 5% Of The Whole, But With 12 Hours' Exposure The Percentage Of Thorium Emanation Rose To About 15.
In two cases, however, it has been found in the absence of appreciable quantities of uranium and thorium compounds, namely in beryl, and in sylvine (potassium chloride).
In 1824 he obtained zirconium from potassium zirconium fluoride; the preparation of (impure) titanium quickly followed, and in 1828 he obtained thorium.
In its chemical relations, titanium is generally tetravalent, and occurs in the same sub-group of the periodic classification as zirconium, cerium and thorium.
Within these limits are to be found most of the minerals known - gold, silver, quicksilver, copper, lead, zinc, iron, manganese, wolfram, bismuth, thorium, vanadium; mica, coal, &c. On or near the coast are coal, salt, sulphur, borax, nitrates and petroleum.