Halogen

Description

Common name for any of the elements from group 7a of the periodic chart: fluorine, chlorine, iodine, bromine, and astatine. Halogens have seven valence electrons in their outer shell which makes them eager to gain an electron to complete their octet. Thus, they are very electronegative. They form negative ions in solution and will react with most metals to form binary salts. Fluorine is the most active of all chemical elements.

Authority

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