What are halogens
The halogens are non-metallic elements found in group 17 of the periodic table. The word Halogens is derived from the Greek word 'hals' meaning "salt" or "sea", and 'gen' from the Greek word 'gígnomai meaning "come to be" for an element that produces a salt when it forms a compound with a metal. All halogens have 7 electrons in their outer shells, giving them an oxidation number of -1. This characteristic makes them more reactive than other non-metal groups. The halogens exist, at room temperature, in all three states of matter: