Final answer:
The elements in Group 7A are called halogens and they have 7 valence electrons. They are highly reactive and readily form halide salts.
Step-by-step explanation:
The elements in Group 7A are called halogens. Each halogen has 7 valence electrons. The term 'halogen' means 'salt-former' because these elements readily react with alkali metal and alkaline earth metals to form halide salts. The halogens have the electron configuration ns²np5, which gives them seven valence electrons and makes them very reactive.