Define halogens.

Group 7 - The halogens

The Group 7 elements are called the halogens.

All the halogens' atoms 'go round in pairs'. 

They form diatomic molecules. In other words, 'two-atom' molecules, like F₂ and Cl₂.

Chlorine changes to chloride in its compounds. In general the halogens form halides.

The halogens get less reactive going down the group.