Yes, CHEMISTRY is a Scrabble word!

Letter values in Scrabble US: C 3, H 4, E 1, M 3, I 1, S 1, T 1, R 1, Y 4.

Is it a valid word?

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

the science of matter; the branch of the natural sciences dealing with the composition of substances and their properties and reactions
the chemical composition and properties of a substance or object
the way two individuals relate to each other

Also: chemical science, interpersonal chemistry.