Relative atomic mass: 232.03806 +- 0.00002

English: Thorium
French: Thorium
Croatian: Torij
German: Thorium
Italian: Torio
Spanish: Torio

Atomic number: 90
Group numbers: 3
Period: 7
Standard state (20 oC): solid

Discovery: 1828 Jons Jacob Berzelius (SE)
Thorium was discovered by Jons Jacob Berzelius (SE) in 1828. Named after Thor, the mythological Scandinavian god of war. It is a heavy, grey, soft, malleable, ductile, radioactive metal that tarnishes in air and reacts with water. It reacts violently with oxidants. Thorium is found in various minerals like monazite and thorite. It is used in making strong alloys, in ultraviolet photoelectric cells. It is a common ingredient in high-quality lenses. When bombarded with neutrons thorium creates uranium-233, a nuclear fuel. The price of 99.8 % pure thorium powder is 464.20 for 10 g.
Electronic configuration: [Rn] 6d2 7s2
Formal oxidation number: +4
Atomic radius: 179.8 pm

Electronegativities: 1.3
Thermal conductivity: 54 W/(m K)
Electrical resistivity (20 oC): 13 microOhm cm

Melting point: 1750 oC
Boiling point: 4788 oC

Heat of fusion: 19.2 kJ/mol
Heat of vaporization: 513.67 kJ/mol
Heat of atomization: 598.65 kJ/mol

89Ac <= 90Th => 91Pa

ASCII Periodic Table of the Elements
29 Aug. 2017
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