Name:

Atomic and Molecular Orbitals Deadline: Next tutorial

Homework #4

1. For each of the following molecules,

i. write the Lewis structure(s),

ii. predict the molecular structure (including geometry and bonding angles),

iii. give the expected hybrid orbitals on the central atom,

iv. predict the overall polarity.

a. OCl2, KrF2, BeH2, SO2

b. SO3, NF3, IF3

c. CF4, SeF4, KrF4

d. IF5, AsF5

e. CO2, H2O, NH3

f. PCl5, SF6, SF4

g. H3O+, I3

-, XeF4

2. Which of the following are predicted by the molecular orbital model to be stable diatomic

species?

a. N22-

, O22-

, F22-

b. Be2, B2, Ne2

3. Using the molecular orbital model to describe the bonding in F2+, F2, and F2

-, predict the

bond orders and the relative bond lengths for these three species. How many unpaired

electrons are present in each species?

4. (a) Give the MO designations for O2, O2-, O2

2-, O2

+, and O2

2+. (b) Give the bond order in

each case. (c) Match these species with the following observed bond lengths: 1.04 , 1.12

, 1.21 , 1.33 , and 1.49 .

5. Using the molecular orbital model, write electron configurations for the following

diatomic species and calculate the bond orders. Which ones are paramagnetic? Place the

species in order of increasing bond length and bond energy.

a. NO+

b. NO

c. NO-

6. Use Lewis formulas to depict the resonance structures of the following species from the

valence bond point of view and then sketch MOs for the delocalized systems:

a. NO3-, nitrate ion

b. HCO3-, hydrogen carbonate ion (H is bonded to O)

c. NO2-, nitrite ion