π* antibonding molecular orbital

Definition

A π* antibonding molecular orbital is a type of molecular orbital formed when atomic orbitals combine in such a way that their electron density resides outside the internuclear axis, leading to decreased stability of the molecule. It is characterized by having a higher energy level than the original atomic orbitals.

5 Must Know Facts For Your Next Test

1. π* antibonding orbitals result from the destructive interference of p-orbitals aligned parallel to each other.
2. Electrons in π* antibonding orbitals destabilize the molecule and decrease its bond order.
3. These orbitals have nodes along the internuclear axis where electron probability is zero.
4. In molecular orbital diagrams, π* antibonding orbitals are typically denoted with an asterisk (*) and lie above the corresponding bonding orbitals in energy.
5. The presence of electrons in π* antibonding orbitals can influence spectroscopic properties and reactivity of molecules.

Review Questions

Related terms

Bonding Molecular Orbital: A lower-energy molecular orbital formed by constructive interference of atomic orbitals, resulting in increased electron density between nuclei and stabilizing the molecule.

Sigma (σ) Bond: A type of covalent bond formed by head-on overlap of atomic orbitals, with electron density concentrated along the internuclear axis.

$\pi$ Bond: $\pi$ bonds are covalent bonds resulting from sideways overlap of p-orbitals, contributing to double and triple bonds alongside $\sigma$ bonds.