Chlorine, bromine and iodine are the three common Group 7 elements. Group 7 elements form salts when they react with metals. The term ‘halogen’ means 'salt former'.
This table summarises some of the properties and uses of three halogens:
|Chlorine||Green gas||Sterilising water|
|Bromine||Orange liquid||Making pesticides and plastics|
|Iodine||Grey solid||Sterilising wounds|
Iodine forms a purple vapour when it is warmed.