Final Exam
December 20, 2000
All references are to articles from J. Am. Chem. Soc., 2000, 122. The exam is open book and open notes.
1. A. Irigoras, O. Elizalde, I. Silanes, J. E. Fowler,
and J. M. Ugalde (p. 114-122) studied the interaction of Cu+
with water when the copper ion was both in the ground state (d10s0)
and an excited state (d9s1). Find all of the Russell-Saunders
term symbols for both states. Answer
2. M. Polášek and F. Turecek (p. 525-531) consider
the chemistry of formaldonitrone, CH2=N(H)O and its isomers.
Draw Lewis dot structures for formaldonitrone and two likely isomers that
maintain the C-N-O linkages. Indicate the formal charge on each atom in
each Lewis dot structure. Predict the C-N-O bond angle (±2o)
for each isomer. Answer
3. L. Glasser and H. D. B. Jenkins (p. 632-638) proposed
a generalized Kapustinskii equation to calculate lattice energies. Their
equation is 
,
where A = 121.4 kJ mol–1 nm, ro is the distance between
ions in nm, 
= 0.0345 nm, and 
(ni
is the stoichiometry of each ion in the formula unit of the ionic compound
and Zi is the charge). Compare the lattice energy of NaCl calculated
using the Born-Landé equation and the generalized Kapustinskii equation.
Comment. Answer
4. R. Minkwitz, A. Kornath, W. Sawodny, V. Typke, and
J. A. Boatz (p. 1073-1078) studied the compound [(CH3S)3S]+SbF6–.
Give the Lewis structure for each ion, the hybridization at the S and Sb
atoms, and the point group for each ion. Do you think the ionic salt will
form a close-packed lattice? Why or why not? Answer
5. C. J. Evans and M. C. L. Gerry (p. 1560-1561) measured
the bond distance in AuF to be 1.918 Å. Based on this determination,
is the bonding in AuF better described as ionic or covalent? Explain your
reasoning. The covalent radius for Au is 1.43 Å; other radii can
be found in your textbook. Answer
6. G. N. Srinivas, T. P. Hamilton, E. D. Jemmis, M. L.
McKee, and K. Lammertsma (p. 1725-1728) considered the electronic properties
of D3h Si3H3+. Use group theoretical
techniques to construct the molecular orbital energy diagram for the 
orbitals in this species. Draw a sketch of each orbital.
Answer
7. M. Essefar, W. Bouab, A. Lamsabhi, J.-L. M. Abboud,
R. Notario, and M. Yáñez (p. 2300-2308) consider the reaction
between R2C=S and I2. Write the product of this reaction.
Draw the Lewis structure of the product when R = H, indicate the formal
charge of each atom, and the oxidation number of each atom. The authors
calculated the enthalpies of reaction to be –18.95 kJ/mole when R = H and
–23.56 kJ/mole when R = CH3. Could this information be used
to find EB and CB for each base? Why or why not?
Answer
8. V. N. Soloviev, A. Eichhöfer, D. Fenske, and U. Banin (p. 2673-2674) found the band gap of CdSe as a function of crystal size. When the crystals have radii on the order of 10-50 nm, the band gap is quite large but when the crystals become micron sized, the band gap is significantly smaller (the size dependence shows an exponential decay with crystal radius). Explain this behavior in terms of band theory. Answer