|
How does the MO picture of these molecules compare with the old
Lewis electron-dot models? This is shown at the bottom of the fillin
th table above. The number of bonds predicted is the same in bo
g theories, but the descriptions of what the electrons are doing
are somewhat different. From B |
onward, each Lewis model has at least one lone electron pair on
each of the atoms. One lone pair from each atom, which contribute
nothing to bonding, correspond to the self-canceling bonding and
antibonding 
and
orbitals
in MO theory. Both theories say that two electron pairs make no
contribution to bonding, but the Lewis model assigns one pair to
each atom, whereas MO theory states that both are shared by the
entire molecule. The sum of 
