is alcl3 polar if not then why does it react with

Question

Is AlCl₃ polar.........? If not then why does it react with H₂O? Also is NaCl non polar?How to decide whether a given compound is polar or not??

solution) If a bond is between atoms off same electronegativity ( essentially same atoms ) then its non polar. Otherwise its polar.

Otherway to check is throough dipole movement. If its there then its polar otherwise not