Hybridization in [Co(NH3)6]Cl3
Hybridization is a concept in chemistry that explains the mixing of atomic orbitals to form new hybrid orbitals suitable for bonding. In the complex ion [Co(NH3)6]Cl3, cobalt has a coordination number of 6, meaning it forms 6 bonds with the ligands.

Cobalt Atom
Cobalt in the complex ion has an electronic configuration of [Ar] 3d7 4s2. To form 6 bonds with ammonia ligands, cobalt undergoes sp3d2 hybridization.

Explanation of Hybridization
- The 3d, 4s, and 4p orbitals of cobalt atom hybridize to form six sp3d2 hybrid orbitals.
- These six hybrid orbitals overlap with the six ammonia ligands to form six σ bonds.
- The remaining empty d orbitals on cobalt may participate in dπ-pπ bonding with chloride ions.

Overall Structure
The complex ion [Co(NH3)6]Cl3 has a distorted octahedral geometry due to the repulsion between lone pairs on the ligands.

Conclusion
In [Co(NH3)6]Cl3, cobalt undergoes sp3d2 hybridization to form six σ bonds with ammonia ligands, resulting in a distorted octahedral geometry for the complex ion.