nCyclopedia Magnetic Quantum Number
Highest Occupied Molecular Orbital (HOMO)
The Highest Occupied Molecular Orbital (HOMO) is the molecular orbital in a molecule that has the highest energy of all the occupied orbitals. An occupied orbital contains at least one electron.
The significance of the HOMO is that it is likely to act as an electron donor and therefore has great influence over how a molecule will interact with other molecules.
Note that a single orbital may be both occupied (have at least one electron) and unoccupied (have room for at least one new electron) at the same time and may therefore be, simultaneoulsly, both the Lowest Unoccupied Molecular Orbital (LUMO) and the HOMO.
