Chem 4701 Inorganic Chemistry
Instructor: Prof. Valerie C. Pierre
T.A.: Sarah Harris
May 18, 2013
There should be 24 pages on this exam.
Please write all answers in the spaces provided; only these will be graded.
If you wri
2.3 Periodic Properties of Atoms | 39
Nonpolar Covalent Radii (pm)
5.2 Homonuclear Diatomic Molecules | 123
5.2.1 Molecular Orbitals
Although apparently satisfactory Lewis electron-dot structures of N2, O2, and F2 can be
drawn, the same is not true with Li2, Be2, B2, and C2, which violate the octet rule. In addition, the
144 Chapter 5 | Molecular Orbitals
FIGURE 5.18 Group Orbital
Symmetry in CO2.
Oxygen Orbitals Used
3. Reducible Representations for Outer Atom Orbitals: In CO2
120 Chapter 5 | Molecular Orbitals
nuclear attraction. Nonbonding orbitals are also possible. The energy of a nonbonding
orbital is essentially that of an atomic orbital, either because the orbital on one atom has
a symmetry that does not match any orbita
Molecular orbital theory uses group theory to describe the bonding in molecules; it complements and extends the introductory bonding models in Chapter 3. In molecular orbital
theory the symmetry properties and relative energie
126 Chapter 5 | Molecular Orbitals
on the basis of s@p mixing, gain either a slightly bonding or slightly antibonding character
and contribute in minor ways to the bonding. Each orbital must be considered separately
on the basis of its energy and electron
5.3 Heteronuclear Diatomic Molecules | 135
Figure 5.13 Molecular rbitals and
hotoelectron Spectrum of CO. Molecular
rbitals 1s and 1s* are from the 1s orbitals
and are not shown.
(Molecular Orbitals and Photoelectron
Spectrum of CO by Kaitlin Hell
138 Chapter 5 | Molecular Orbitals
difference (and without considering the MO diagram), compounds in which CO is bonded
to metals, called carbonyl complexes, would be expected to bond as M:O:C with the
more electronegative oxygen attached to the electropo
5.4 Molecular Orbitals for Larger Molecules | 141
Fluorine Orbitals Used
FIGURE 5.16 Interaction of
Fluorine Group Orbitals with the
Hydrogen 1s Orbital.
The central hydrogen atom in FHF - , with only its 1s orbital
5.4 Molecular Orbitals for Larger Molecules | 147
The 2py orbital of carbon has B2u symmetry and interacts with group orbital 5
(Figure 5.23). The result is the formation of two p molecular orbitals, one bonding and
one antibonding. However, there is no c
6.3 BrnstedLowry Concept | 175
6.3.3 Thermodynamic Measurements in Solution
Various thermodynamic approaches have been used to probe acidity and basicity in solutions.
The impact of solvation effects must always be considered when designing these experime
172 Chapter 6 |
AcidBase and DonorAcceptor Chemistry
E X E R C I S E 6 .1
Calculate the concentration of CH3CNH + in CH3CN at 25 C.
Consider the net ionic equation for the reaction of a strong acid (HCl) and strong base
(NaOH) in aqueous solution. In wate
156 Chapter 5 | Molecular Orbitals
Figure 5.30 Molecular
rbitals of NH3. All are shown
with the orientation of the
molecule at the bottom.
(Molecular Orbitals of NH3 by
Kaitlin Hellie. Reprinted by
matching their symmetries to the correspo
5.4 Molecular Orbitals for Larger Molecules | 159
As discussed in Chapter 3, consideration of all resonance structures for BF3
suggests that this molecule possesses some double-bond character in the B i F bonds.
The molecular orbital view of BF3 has an el
Problems | 165
1. F. Luo, G. C. McBane, G. Kim, C. F. Giese, W. R. Gentry,
J. Chem. Phys., 1993, 98, 3564; see also L. L.Lohr,
S.M.Blinder, J. Chem. Educ., 2007, 84, 860, and
references cited therein.
2. M. Atoji, J. Chem. Phys., 1961, 35, 1950
162 Chapter 5 | Molecular Orbitals
For example, in methane, the vectors point at the corners of a tetrahedron or at alternate corners of a cube (Figure 5.33).
Using the Td point group, these four vectors form the basis of a reducible representatio
150 Chapter 5 | Molecular Orbitals
4. The representation can be reduced to the irreducible representations A1 + B1, representing the symmetries of the group orbitals. In Step 5 these group orbitals will be
matched with oxygen orbitals of matching symmetri
168 Chapter 5 | Molecular Orbitals
b. Account for the bonding in Cl4 + . This ion contains
two short Cl i Cl bonds and two much longer ones.
Would you expect the shorter Cl i Cl distances in Cl4 +
to be longer or shorter than the
132 Chapter 5 | Molecular Orbitals
FIGURE 5.10 Photoelectron
Spectrum and Molecular Orbital
Energy Levels of N2. Spectrum
simulated by Susan Green
using FCF program available
at R. L. Lord, L. Davis, E. L.
Millam, E. Brown, C. Offerman,
P.Wray, S. M. E. G
5.2 Homonuclear Diatomic Molecules | 129
The extent of mixing is not sufficient in O2 to push the sg(2p) orbital to higher energy
than the pu 12p2 orbitals. The order of molecular orbitals shown is consistent with the
photoelectron spectrum, discussed in
Problems | 111
1. M. Gerken, G. J. Schrobilgen, Inorg. Chem., 2002,
2. J. A. Boatz, K. O. Christe, D. A. Dixon, B. A. Fir,
M.Gerken, R. Z. Gnann, H. P. A. Mercier, G. J.
Schrobilgen, Inorg. Chem., 2003, 42, 5282.
78 Chapter 4
| Symmetry and Group Theory
Squares, rectangles, parallelograms, rectangular solids, octahedra, and snowflakes
have inversion centers; tetrahedra, triangles, and pentagons do not (Figure 4.5).
4.2 Point Groups | 87
Further Examples of C and D Point Groups
Point Group and Example
BrF5 (square pyramid)
84 Chapter 4
| Symmetry and Group Theory
2. Find the rotation axis with the highest n, the highest order Cn (or principal) axis
for the molecule.
The rotation axes for the examples are shown in Figure 4.9. Some molecules feature
72 Chapter 3 |
Simple Bonding Theory
3.13 a. Compare the structures of the azide ion, N3 - , and the
ozone molecule, O3.
b. How would you expect the structure of the ozonide ion,
O3 - , to differ from that of ozone?
3.14 Consider the series OCl2, O(CH3)2,
Simple Bonding Theory
We now turn from the use of quantum mechanics and its description of the atom to an elementary description of molecules. Although most of our discussion of chemical bonding
uses the molecular orbital approach, less rigo