Yes, QIS is a Scrabble word!

Letter values in Scrabble US: Q 10, I 1, S 1.

Is it a valid word?

QIS is a valid word in the official Scrabble dictionary (US) and the UK Scrabble Dictionary, but not in 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

Also: ch'i.