Thorium (atomic symbol "Th", atomic number = 90, atomic weight = 232.0381) is a naturally-occuring radioactive metal; it is classified in the actinide series of the periodic table. It has a high melting point, and is sometimes alloyed with magnesium because it increases the strength of the magnesium at high temperatures. Its primary use is in Welsbach mantles in gas lamps.

Thorium
Symbol: Th
Atomic Number: 90
Atomic Weight: 232.0381
Boiling Point: 5060 K
Melting Point: 2028 K
Density at 300K: 11.72 g/cm³
Covalent radius: 1.65
Atomic radius: ???
Atomic volume: 19.90 cm³/mol
First ionization potental: 6.08 V
Specific heat capacity: 0.113 Jg^-1K^-1
Thermal conductivity: 54 Wm^-1K^-1
Electrical conductivity: 7.1*10⁶Ω^-1m^-1
Heat of fusion: 15.65 kJ/mol
Heat of vaporization: 543.92 kJ/mol
Electronegativity: 1.3 (Pauling's)

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Other uses for thorium:

A coating for tungsten filaments used in electronic devices such as televisions

Thorium oxide has a very high melting point and is used to make high temperature crucibles

Thorium oxide is used to make glass with a high index of refraction for high quality camera lenses

Thorium oxide is used as a catalyst in the production of sulfuric acid, and in the conversion of ammonia to nitric acid

Tho"ri*um (?), n. [NL. See Thorite.] Chem.

A metallic element found in certain rare minerals, as thorite, pyrochlore, monazite, etc., and isolated as an infusible gray metallic powder which burns in the air and forms thoria; -- formerly called also thorinum. Symbol Th. Atomic weight 232.0.

 

© Webster 1913.