Doc Brown's Chemistry Clinic: The Halogens
   Includes an overview, general properties, reactivity trends, and information about the industrial electrolysis of sodium chloride solution.
   http://www.wpbschoolhouse.btinternet.co.uk/page03/The_Halogens.htm

The Chemistry of the Halogens
   Covers their properties, methods of preparation, general trends, the hydrogen halides, and oxyacids of the halogens and their salts.
   http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch10/group7.php

Visual Elements: The Halogens
   Overview, general properties, and chemical data for the group.
   http://www.chemsoc.org/viselements/pages/data/intro_groupvii_data.html