Unit 2: Part Six - Molecular Orbital (MO) Theory
Be able to construct molecular orbital energy diagram from homonuclear diatomic species from the first and second period
homonuclear = H2, O2
Relate stability to bond order
As the bond order increases the stability increases
Use the molecular orbital energy diagram to calculate bond order
B.O> = (# of bonding electrons - # of antibonding)/2
Distinguish between bonding and antibonding molecular orbitals
Bonding molecular orbitals - refers to constructive interference where a bond is formed and the atomic orbitals are in phase. Antibonding molecular orbitals - refers to destructive interference where a bond isn't formed/ favored and the atomic orbitals are out of phase.
Explain how the atomic orbitals and molecular orbitals are different
In the molecular orbitals all the electrons belong to the molecule as a whole and no two electrons are localized between two atoms.
Be able to fill a MO energy diagram correctly
Look at the examples provided in class and homework
Explain how a sigma and pi molecular orbitals are different
Sigma is connected while a pi nod is not.
Distinguish between the main concepts of the VB Theory and the MO Theory
The MO theory gives better description of electrons clouds distribution in chemical bonding. It is also very helpful in examining bond energies and magnetic properties.
Discuss the shortcomings of the VB Theory
VB theory can make incorrect predictions about electronic structures of some molecules. (i.e. O2). The VB theory also does not give a good description of delocalized electrons.
Know how the molecular orbital energy diagram for diatomic species in the second period is different for O2, F2, (and Ne2) than it is for LI2, Be2, B2, C2, and N2.
Z-average <8 Z-average >/= 8
Relate bond energy, bond length, and bond strength to bond order.
as the bond order increases the bond length decreases and both the bond energy/ strength increase.
Use the molecular orbital energy diagram to determine the magnetic properties of diatomic molecules and ions
diamagnetic = no unpaired electron Paramagnetic = at least on unpaired electron
