Yes, ALAMOS is a Scrabble word!

Letter values in Scrabble US: A 1, L 1, A 1, M 3, O 1, S 1.

Is it a valid word?

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

a siege and massacre at a mission in San Antonio in 1836; Mexican forces under Santa Anna besieged and massacred American rebels who were fighting to make Texas independent of Mexico