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Frost Circle definitions

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  • Frost Circle
    A diagrammatic tool using polygons to visualize molecular orbital energy levels in cyclic compounds.
  • Hückel's Rule
    A guideline stating that aromatic stability arises when a molecule has 2, 6, 10, 14, etc., pi electrons.
  • Molecular Orbital
    A region in a molecule where electrons are likely to be found, depicted at each polygon vertex in the method.
  • Bonding Orbital
    An energy level below the nonbonding line in the Frost circle, filled first and contributing to molecular stability.
  • Antibonding Orbital
    An energy level above the nonbonding line, filled only after all bonding orbitals are occupied, leading to instability.
  • Nonbonding Line
    The horizontal divider in the Frost circle separating bonding from antibonding molecular orbitals.
  • Pi Electron
    An electron occupying a molecular orbital formed from sideways overlap of p orbitals in a ring system.
  • Degenerate Orbitals
    Orbitals of equal energy, requiring even electron distribution according to Hund's rule.
  • Aromaticity
    A property of cyclic molecules with completely filled bonding orbitals, resulting in exceptional stability.
  • Antiaromaticity
    A property of cyclic molecules with partially filled bonding orbitals, causing unique instability.
  • Aufbau Principle
    A rule dictating that electrons fill the lowest available energy orbitals before higher ones in the Frost circle.
  • Hund's Rule
    A rule requiring electrons to occupy degenerate orbitals singly before pairing up.
  • Inscribed Polygon Method
    A technique for drawing polygons with one vertex down to represent molecular orbital energy levels.
  • Cyclobutadiene
    A four-membered ring molecule used as an example of antiaromatic instability due to non-Hückel pi electron count.
  • Cyclopropenyl Anion
    A three-membered ring with a negative charge, illustrating antiaromaticity in the Frost circle method.