Chemistry, The Central Science, 10th edition
Theodore L. Brown; H. Eugene LeMay, Jr.;
and Bruce E. Bursten
Chapter 9
Molecular Geometry and
Bonding Theories
Troy Wood
University of Buffalo
Buffalo, NY
 2006, Prentice Hall
In a tetrahedral molecule the bond
angles are _________.
1. 90°
2. 109.5°
3. 120°
4. 180°
Correct Answer:
1. 90°
2. 109.5°
3. 120°
4. 180°
As shown in the illustration, in
a perfect tetrahedron the bond
angles are 109.5º.
In which of the following molecules
is the HXH bond angle smallest
(X is non-H atom): CH4, H2O, and
NH3?
1. CH4
3. NH3
2. H2O
4. They are all equal.
Correct Answer:
1. CH4
2. H2O
3. NH3
4. They are all equal
Electron domains for nonbonding electron pairs
exert greater repulsive forces on adjacent
electron domains; thus, the bond angles are
compressed with increasing numbers of
nonbonding electron pair domains.
Using VSEPR, predict the molecular
geometry of NH3.
1. Linear
2. Trigonal planar
3. Trigonal pyramidal
4. Tetrahedral
Correct Answer:
1. Linear
2. Trigonal planar
3. Trigonal pyramidal
4. Tetrahedral
As indicated in the
illustration, the
molecular geometry of
NH3 is trigonal
pyramidal.
Using VSEPR, predict the molecular
geometry of SF4.
1. T-shaped
2. Seesaw-shaped
3. Trigonal bipyramidal
4. Linear
Correct Answer:
1. T-shaped
2. Seesaw-shaped
3. Trigonal bipyramidal
4. Linear
As indicated in the
illustration, the
molecular geometry of
SF4 is seesaw.
Using VSEPR, predict the molecular
geometry of O3.
1. Bent
2. Trigonal planar
3. Trigonal pyramidal
4. Linear
Correct Answer:
1. Bent
2. Trigonal planar
3. Trigonal pyramidal
4. Linear
As indicated in the
illustration, the
molecular geometry of
O3 is bent.
SO2: Polar or nonpolar?
1. Polar
2. Nonpolar
Correct Answer:
1. Polar
2. Nonpolar
Clearly from the bond dipoles the molecule SO2
will exhibit a net overall dipole, thus being a
polar molecule.
CO2: Polar or nonpolar?
1. Polar
2. Nonpolar
Correct Answer:
1. Polar
2. Nonpolar
The bond dipoles in
CO2 cancel one
another such that
the molecule will
exhibit no net overall
dipole. Thus, it is a
nonpolar molecule.
Which kind of hybridization is about
the central atom in PCl5?
1. sp2
2. sp3
3. sp4
4. sp3d
Correct Answer:
1. sp2
2. sp3
3. sp4
4. sp3d
The hybridization for
PCl5 is sp3d, as
shown to the right.
In the molecule HCN, how many
sigma bonds (s ) and how many pi
bonds (p ) are there?
1. One sigma, one pi
2. Two sigma, one pi
3. Two sigma, two pi
4. None of the above
Correct Answer:
1. One sigma, one pi
H
C
N
2. Two sigma, one pi
3. Two sigma, two pi
One sigma
4. None of the above
Total = Two sigma + two pi
One sigma
Two pi
In the molecule C2H4, how many
sigma bonds (s ) and how many pi
bonds (p ) are there?
1. Five sigma, one pi
2. Four sigma, two pi
3. Six sigma, zero pi
4. None of the above
Correct Answer:
1. Five sigma, one pi
2. Four sigma, two pi
3. Six sigma, zero pi
4. None of the above
The sigma and pi bonds
for C2H4 are indicated in
the illustration.
What is the bond order of the He2+ ion?
1. 0
2. +1 2
3. 1 2
4. 1
Correct Answer:
1. 0
2. +1 2
3. 1 2
4. 1
Bond order = 1 2 (# bonding e – # nonbonding e)
Bond order = 1 2 (2 – 1) = 1 2
Is molecular O2 paramagnetic or
diamagnetic?
1. Paramagnetic
2. Diamagnetic
Correct Answer:
1. Paramagnetic
2. Diamagnetic
Molecular O2 is diamagnetic because each
molecule contains two unpaired electrons.