Yes, PHOENIX is a Scrabble word!

Letter values in Scrabble US: P 3, H 4, O 1, E 1, N 1, I 1, X 8.

Is it a valid word?

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

the state capital and largest city located in south central Arizona; situated in a former desert that has become a prosperous agricultural area thanks to irrigation
a large monocotyledonous genus of pinnate-leaved palms found in Asia and Africa
a legendary Arabian bird said to periodically burn itself to death and emerge from the ashes as a new phoenix; according to most versions only one phoenix lived at a time and it renewed itself every 500 years
a constellation in the southern hemisphere near Tucana and Sculptor

Also: capital of arizona, genus phoenix.