Thorium

Description

A soft, silvery radioactive metallic element. Thorium was discovered by Baron Berzelius, a Swedish chemist in 1929. It has an abundance of about 8-15 ppm in the earth's crust and occurs mainly in the minerals thorite, thorianite, orangite, yttrocrasite, and monazite sand. Metallic thorium is a malleable and ductile. It turns dark and oxidizes in air. Thorium is used in the manufacture of ceramics, sun lamps, photoelectric cells, incandescent gaslight mantles, and welding electrodes.

Synonyms and Related Terms

Th

Other Properties

Soluble in acids. Insoluble in water, alkalis.

Composition	Th (atomic no. 90)
CAS	7440-29-1
Melting Point	1750-1800
Density	11.0-11.7
Molecular Weight	atomic wt = 232.038
Boiling Point	4700-4800

Hazards and Safety

Powder is flammable and explosive. Radioactive.

Authority

• G.S.Brady, G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 807

• Douglas M. Considine (ed.), Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976

• Random House, Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997

• The American Heritage Dictionary or Encarta, The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998

• Richard S. Lewis, Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993

• Martha Windholz (ed.), The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983 Comment: entry 9514