Beginning Organic Chemistry (BOC)
1. Basic Knowledge
e. Molecular Orbitals and Bonding.
Return to BOC Index.
Single Bonds| Double Bonds| Triple Bonds | High Energy Intermediates
Although the Kekulé structures for molecules can reveal much about a molecule, sometimes it is necessary to use a more complex theory. According to quantum mechanics, sharing of electrons to form stable molecules occurs when electrons can move into wave forms with lower energies which are centred over more than one atom. Electrons in such waveforms do not have enough energy to move back into wave forms centred on one nucleus (atomic orbitals) and so the atoms remain together in a molecule.
In your first year course you meet the series of homonuclear diatomic molecules and the molecular wave forms (molecular orbitals, abbreviated mo) that can be calculated for those using a linear combination of atomic orbitals approach. The molecular orbitals for nitrogen are modeled at the University of Arizona site already visited. At this site look at the shapes of the s2p and p2p orbitals and the corresponding antibonding orbitals. (When the structure has downloaded into chime, switch the view to spacefilling.)
Some times it is important to use molecular orbitals to describe why certain events take place, or why a certain structure is more stable than might be expected. Most times in organic chemistry, though, models based on the simple Lewis or Kekulé structures have enough detail to be useful.
Date created: 2005 06 09.