Question

What is a sigma bond in chemistry?

Answer 1

The strongest type of covalent bond.

Explanation:

Sigma bonds form via the "head on" overlapping of atomic orbitals of the component atoms, so `s+s, p_z+p_z, s+p_z and d_z^2+d_z^2` (z being the bond axis).

Single bonds are typically sigma only, whilst double/triple bonds contain a mixture of sigma and pi bonding. But sigma is the only type that is "head to head" direct overlapping of electron orbitals, which makes them stronger.