Yes, CHIS is a Scrabble word!

Letter values in Scrabble US: C 3, H 4, I 1, S 1.

Is it a valid word?

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

the circulating life energy that in Chinese philosophy is thought to be inherent in all things; in traditional Chinese medicine the balance of negative and positive forms in the body is believed to be essential for good health
the 22nd letter of the Greek alphabet

Also: ch'i.