Atoms, bonding and types of reactions

Ethane

For Carbon-Carbon bond formation, consider ethane, C₂H₆. As before, each Carbon atom undergoes hybridisation giving four sp³ orbitals for the formation of four bonds.

Each Carbon atom bonds to three Hydrogens. As before, each Hydrogen 1s orbital merges with a Carbon sp³ orbital to give a σ-bond. As there are three Hydrogens to bond with each Carbon, one of the four sp³ orbitals remains for each Carbon.

The remaining hybrid orbitals, one on each Carbon, undergo end-to-end overlap with each other to give a new molecular bonding orbital. Again, this merging produces a σ-bond with two electrons shared within it.

It is important to note that there is free rotation around σ-bonds as it does not compromise the end-to-end overlap required for bonding.