Alternancy symmetry

{
  "id": "MLC-T-CHM-000451",
  "term": "Alternancy symmetry",
  "field": "Chemistry",
  "definition": "A property observed in certain conjugated hydrocarbons, particularly alternant hydrocarbons, where the carbon atoms can be divided into two sets, 'starred' and 'unstarred', such that no two atoms of the same set are directly bonded. This symmetry leads to specific patterns in the molecular orbital energy levels and electron densities. For example, in alternant hydrocarbons, bonding and antibonding molecular orbitals occur in pairs with energies symmetrically distributed around the non-bonding level.",
  "subject": "Organic and Biomolecular Chemistry",
  "see_also": [
    "alternant",
    "hydrocarbons"
  ],
  "references": [
    "PAC, 1999, 71, 1919. 'Glossary of terms used in theoretical organic chemistry' on page 1922 (https://doi.org/10.1351/pac199971101919)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/alternancy-symmetry/"
}