Question

AlcL 3 forms dimer explain the bonding with detail.​

Answer 1

In $AlCl_{3},$ aluminium has got $\bold{6\:electrons}$ in its valence shell..

So, in order to complete its octet, it requires $\bold{2\:more\: electrons..}$

Now..

It accepts a lone pair of $\bold{electrons}$..

That is, from $\bold{Cl}$ of the neighbouring $AlCl_{3}$molecule..

In doing this,

One of the chlorine atoms donates an electron pair to the electron deficient $\bold{Al}$ atom of the neighbouring $AlCl_{3}$ molecule resulting in the formation of a dimer..

This is how, $AlCl_{3}$ forms dimer..

Answer 2

Refer the attached picture.

$\sf{\huge{EXPLANATION}}$ :

In AlCl3, there are 6 electrons around aluminium and are two less than the octet. So, Al in AlCl3 is $\bold{electron \:deficient}$ whereas Cl atom has a lone pair of electrons to donate. Therefore, each Al atom completes its octet by accepting a lone pair from Cl atom of another aluminium chloride molecule. Thus, it forms dimer.