Thorium • Actinide Rare Earth
Date of discovery: 1828
Name origin: Scandinavian Thor
Discoverer: Jons Berzelius
Obtained from: monazite, thorite
Melting point: 2023 K
Boiling point: 5063 K
Molar volume: 19.80 × 10-6 m3/mol
Shell structure: 2,8,18,32,18,10,2
Electron configuration: [Rn]6d27s2
Oxidation state: 4
Crystal structure: cubic face centered
Named after Thor, a Scandinavian god of war, thorium is about three times more abundant than uranium. It is found in small amounts in rocks and soils, with abundant supplies in several countries. Monazite, a rare-earth and thorium-phosphate mineral containing twelve percent thorium oxide, is the primary source of the world’s thorium. Similar to uranium, thorium can be used as a fuel in a nuclear reactor and is a key factor in the sustainability of nuclear energy. Much of the earth’s heat is attributed to the decay of both uranium and thorium. When exposed to air, the element retains a silverish white color for about three months then slowly tarnishes to a grey then black color. The primary use of thorium is for strong alloys and ultraviolet photoelectric cells.
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