Question

What is the exception to the octet rule with aluminum?

Answer 1

In some of its compounds, aluminum violates the octet rule by having only six valence electrons.

For example, aluminum chloride, AlCl₃, has only six valence electrons around the Al atom.

However, AlCl₃ exists only at high temperatures. At ordinary temperatures, two molecules of AlCl₃ combine to form Al₂Cl₆. In this structure, both Al atoms do satisfy the octet rule.