Question

The AlI3 molecule has an incomplete octet around Al. Draw three resonance structures of the molecule in which the octet rule is satisfied for both the Al and the I atoms. Show formal charges.

Answer 1

Resonance structures arise due to back bonding between vacant 3p orbital on Al atom and three lone pairs are present on each I atom.

Step-by-step explanation:

In Lewis structure of
`AlI_(3)` (with incomplete octet), there is a vacant 3p orbital on Al atom and three lone pairs are present on each I atom.

So, a back bonding is possible between these lone pair and vacant orbital. Three back bonding from three different I atoms create three resonance structures of
`AlI_(3)`.

In these resonance structures, octet of Al gets satisfied as Al shares a new covalent bond.

Resonance structures are shown below.