Yes, OXIDATIONS is a Scrabble word!

Letter values in Scrabble US: O 1, X 8, I 1, D 2, A 1, T 1, I 1, O 1, N 1, S 1.

Is it a valid word?

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

the process of oxidizing; the addition of oxygen to a compound with a loss of electrons; always occurs accompanied by reduction

Not playable in Scrabble US: OXIDIZATION, OXIDISATION.