Describe the change in hybridization (if any) of the `Al` atom in the following:
`AlCl_(3)+Cl^(ө)rarr AlCl_(4)^(ө)`

Explanation

The valence orbital picture of aluminium in the ground state can be represented as :

The orbital picture of aluminium in the excited state can be respresented as :
Hence, it undergoes `sp^(2)` hybridization to give a trigonal planar arrangement (in `AlCl_(3)`). To form `AlCl_(4)^(-)`, the empty `3p_(z)` orbital also get involved and the hybridization changes from `sp^(2)` to `sp^(3)`. As a result, the shape gets changed to tetrahedral.