Yes, NEWTONS is a Scrabble word!

Letter values in Scrabble US: N 1, E 1, W 4, T 1, O 1, N 1, S 1.

Is it a valid word?

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

English mathematician and physicist; remembered for developing the calculus and for his law of gravitation and his three laws of motion (1642-1727)
a unit of force equal to the force that imparts an acceleration of 1 m/sec/sec to a mass of 1 kilogram; equal to 100,000 dynes

Also: isaac newton, sir isaac newton, n.