Yes, HALOGEN is a Scrabble word!

Letter values in Scrabble US: H 4, A 1, L 1, O 1, G 2, E 1, N 1.

Is it a valid word?

HALOGEN is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

any of five related nonmetallic elements (fluorine or chlorine or bromine or iodine or astatine) that are all monovalent and readily form negative ions