What is the ionic bonding of aluminium chloride?

Answer 1

AlCl3 has simple covalent bonding because the aluminium cation is so small and highly charged (3+) that it has an extremely high charge density. This charge density distorts the electron cloud of the anions (Cl-) to such a large degree that the bonding is considered as covalent. This is why AlCl3 vapourises at room temperature, because it only has weak van der waal's intermolecular forces.

Well I didn't write this! AlCl3 is a white crystalline solid with a melting point of 1920

It does NOT vapourise at room temperature!

In the solid the aluminium has 6 chlorine atoms around it. The bonding is more ionic than covalent. At the melting point the structure changes to a dimer with a formula of Al2Cl6 with four chlorines around each aluminium atom. In this state the bonding is covalent.

Answer 2

AlCl3 is ionic in the solid- unlike AlBr3 where there are dimers Al2Br6. In AlCl3 the aluminium ions, Al3+ are surrounded by 6 chloride ions