Sigma bonds (σ bonds)

Definition

Sigma bonds (σ bonds) are covalent bonds formed by the head-on overlap of atomic orbitals. They allow for free rotation around the bond axis.

5 Must Know Facts For Your Next Test

1. Sigma bonds are the strongest type of covalent bond due to direct orbital overlap.
2. They can form between s-s, s-p, or p-p orbitals.
3. Every single covalent bond is a sigma bond, but multiple bonds also contain pi (π) bonds in addition to a sigma bond.
4. Sigma bonds have cylindrical symmetry around the bond axis.
5. Bonding molecular orbitals created from sigma bonding are lower in energy compared to their associated atomic orbitals.

Related terms

Pi Bonds (π Bonds): Covalent bonds formed by the side-by-side overlap of p orbitals, present in double and triple bonds along with a sigma bond.

Valence Bond Theory:

A theory that explains the formation of chemical bonds through the overlap of atomic orbitals.

Molecular Orbital Theory: $\text{A theory that describes bonding in terms of molecular orbitals which are combinations of atomic orbitals spread over a molecule.}$