Yes, AFFRICATIVE is a Scrabble word!

Letter values in Scrabble US: A 1, F 4, F 4, R 1, I 1, C 3, A 1, T 1, I 1, V 4, E 1.

Is it a valid word?

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

a composite speech sound consisting of a stop and a fricative articulated at the same point (as `ch' in `chair' and `j' in `joy')

Also: affricate consonant.