Yes, TROPICS is a Scrabble word!

Letter values in Scrabble US: T 1, R 1, O 1, P 3, I 1, C 3, S 1.

Is it a valid word?

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

the part of the Earth's surface between the Tropic of Cancer and the Tropic of Capricorn; characterized by a hot climate
either of two parallels of latitude about 23.5 degrees to the north and south of the equator representing the points farthest north and south at which the sun can shine directly overhead and constituting the boundaries of the Torrid Zone or tropics

Also: torrid zone, tropical zone.