Name __________________________ Test 1
PHYS 0201 (Organic) Fall 2004
1.
Drawn below is an incomplete molecular orbital (MO) diagram for the molecule HF.
a.
b.
c.
d.
(3 pts.) Label t he
atomic orbitals.
(2 pts.) Label t he
bonding and
antibonding molecular
orbitals.
(3 pts.) Complete the
diagram by adding
electrons to the
appropriate energy
levels.
(2 pts.) Determine the
bond order for HF.
BO = (2 โ 0)/2 = 1
H F
2s
2px2py2pz
1s
!*
!
HF
e.
(2 pts.) Determine the effect that removing an electron would have on the strength of the HF
bond.
No effect because a nonbonding electron is removed. BO = (2 โ 0)/2 = 1
f.
(2 pts.) Determine the effect that exciting an ele ctron from t he HOMO to the LUMO would
have on the strength of the HF bond.
A nonbonding electron is promoted to an anti bonding orbital. BO = (2 โ 1)/2 = 0.5. The bond
strength is lower.
2.
(4 pts.) Which of the following statements more accurately describes the reason for using
orbital hybridization as a means for explaining bonding?
Hybridization is absolutely necessary in order to create orbitals to hold the electrons that are
used to make a molecule. (incorrect)
Hybridization is a simple but useful model for accounting for the arrangement of
electrons around an atom in a molecule. (corr ect)
