Cesium

Description

An element in the alkali metal group. Cesium has an abundance of 1 ppm in the earth's crust. It occurs in the minerals pollucite and lepidolite. Cesium was discovered in 1860 by Robert Bunsen and Gustav Kirchhoff. It is a soft, silvery white metal that tarnishes on contact with air and can ignite spontaneously in moist air. Cesium is used as a catalyst for polymers and as a radioactive emitter in atomic clocks. It is also used in photoelectric sensors for security devices and cameras.

Synonyms and Related Terms

Cs; caesium (IUPAC); cesium (US,. Ned., Sven.); césium (Fr.); Cäsium (Deut.); cesio (It., Esp.); Césio (Port.)

Risks

• Metallic cesium can ignite spontaneously in moist air.
• Dangerous fire and explosion risk.
• Reacts violently with oxidizing materials.
• Burns skin.
• Fisher Scientific: MSDS

Physical and Chemical Properties

• Flame color is blue to purple.
• Violently decomposes in water with the evolution of hydrogen.
• Soluble in liquid ammonia.

Composition	Cs (atomic no. 55)
CAS	7440-46-2
Mohs Hardness	0.2
Melting Point	28.5 C
Density	1.873 g/ml
Molecular Weight	atomic wt. =132.9054
Boiling Point	705 C

Resources and Citations

• Web Elements: Website

• G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 180

• 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 2051

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