Thulium

Description

A rare-earth element of the yttrium group. Thulium was discovered in 1879 by P.T.Cleve, a Swedish chemist. It has an abundance of 0.48 ppm in the earth's crust. Thulium occurs in rare earth minerals such as euxenite, ytterspar, sipylite and gadolinite. It is a silvery-white, metal that is easily worked. Thulium is used as a radioactive source in small, portable x-ray machines.

Synonyms and Related Terms

Tm

Risks

• Dust is flammable.
• Sensitive to moisture and air.
• Fisher Scientific: MSDS

Physical and Chemical Properties

Soluble in dilute acids. Reacts slowly with water.

Composition	Tm (atomic no. 69)
CAS	7440-30-4
Melting Point	1545-1550 C
Density	9.318 g/ml
Molecular Weight	atomic wt = 168.934
Boiling Point	1725-1727 C

Resources and Citations

• G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 179

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

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

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

• The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983 Comment: entry 9535

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