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molecular orbital
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Diagram showing the six pi molecular orbitals of a benzene molecule, arranged by increasing energy levels. Each orbital is illustrated with colored lobes representing electron density, and energy levels are labeled 1a, 1e, 2e, and 2a, with electron occupancy indicated by arrows.
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molecular orbital

chemistry
Also known as: MO
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Diagram showing the six pi molecular orbitals of a benzene molecule, arranged by increasing energy levels. Each orbital is illustrated with colored lobes representing electron density, and energy levels are labeled 1a, 1e, 2e, and 2a, with electron occupancy indicated by arrows.
benzene Figure 15: The six π molecular orbitals of a benzene molecule and their relative energies. Only the three lowest-energy orbitals are occupied in benzene. The bonding and antibonding character of these orbitals is distributed around the ring of carbon atoms. The dashed lines represent nodal planes, and the shading reflects the two possible phases of the orbitals. Constructive interference, resulting in an area of high electron density, occurs between like phases; destructive interference, resulting in a nodal plane, occurs between unlike phases.

Molecular orbital (MO) theory is a quantum mechanical approach to understanding chemical bonding. It describes how atomic orbitals combine to form molecular orbitals, which are wave functions representing the probable location of electrons across all nuclei in a molecule. This theory provides a more detailed and quantitative understanding of molecular structures and properties than simpler models.123

In MO theory, molecular orbitals are constructed from atomic orbitals, often using the linear combination of atomic orbitals (LCAO) approximation. These molecular orbitals can be bonding (lower energy, increased electron density between nuclei) or antibonding (higher energy, reduced electron density between nuclei). The distribution of electrons into these orbitals, following principles like the Pauli exclusion principle, explains bond strengths, molecular stability, and properties like paramagnetism. MO theory is a principal model for computational chemistry and offers insights into delocalized electrons, which is particularly useful for understanding the properties of larger molecules.3245

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5 Britannica Sources
  1. chemical bonding - Molecular orbitals of period-2 diatomic molecules
  2. chemical bonding - Molecular orbitals of H 2 and He 2
  3. molecular orbital
  4. chemical bonding - Comparison of the VB and MO theories
  5. chemical bonding - Molecular orbitals of polyatomic species

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