We know a compound could form between NaCl because they are +1 and -1 ions which make them both into a complete valence set.
Could a compound form between Al and Br, for example, and what type of bond would this be? Would such a compound never form because it is not 'stable' (both atoms having a complete octet, like NaCl)?
It is said that a bond between a metal and non-metal such as this must be Ionic. If this is the case then it violates the rule that the Electronegativity difference must be > 1.7. The EN difference is only ~1.3 between Al and Br, which would indicate a Covalent bond instead. Which is correct?