Yes, ACTIVATED is a Scrabble word!

Letter values in Scrabble US: A 1, C 3, T 1, I 1, V 4, A 1, T 1, E 1, D 2.

Is it a valid word?

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

put in motion or move to act
make active or more active
make more adsorptive
aerate (sewage) so as to favor the growth of organisms that decompose organic matter
make (substances) radioactive

(of sewage) treated with aeration and bacteria to aid decomposition
(of e.g. a molecule) made reactive or more reactive
rendered active; e.g. rendered radioactive or luminescent or photosensitive or conductive
(military) set up and placed on active assignment

Also: set off, spark off, trigger off, touch off.