Chap13_MO-2 - are lower in energy than the original atomic...

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MOLECULAR ORBITAL THEORY Examples of when MO theory is more useful than valence bond theory Valence bond theory makes incorrect predictions about electronic structures of some molecules, such as O 2 . Valence bond theory does not give a good description of delocalized electrons. KEY IDEAS Molecular orbitals (MOs) are to molecules what atomic orbitals are to atoms. All electrons belong to the molecule as a whole and no two electrons are localized between two atoms. Just like atomic orbitals, MOs have a specific size, shape, and energy level. Molecular orbitals form from combination of atomic orbitals. The number of formed molecular orbitals equals the number of combined atomic orbitals. When atomic orbitals combine, they form molecular orbitals which
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Unformatted text preview: are lower in energy than the original atomic orbitals and molecular orbitals which are higher in energy that the original atomic orbitals. MOs which are lower in energy are called bonding MOs and MOs which are higher in energy are called antibonding MOs. We must fill the MOs with the correct number of electrons for the molecules, following the Aufbau method, Hunds Rule and Pauli exclusion principle. BOND ORDER AND BOND STABILITY B.O = (# of bonding electrons - # of antibonding electrons)/2 The greater the bond order of a specie, the more stable the specie is. The greater the bond order, the shorter is the bond length and the greater is the bond energy....
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This note was uploaded on 12/04/2010 for the course BIO 311 C taught by Professor Mcclelland during the Spring '09 term at University of Texas at Austin.

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