Yes, ACTIVES is a Scrabble word!

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

Is it a valid word?

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

chemical agent capable of activity
the voice used to indicate that the grammatical subject of the verb is performing the action or causing the happening denoted by the verb
a person who is a participating member of an organization

Also: active agent, active voice.