Chem 103
Chem 103 Exam 3 Questions and Answers Top
Graded 2026
Part 1: Molecular Geometry & VSEPR
1. Which molecule has a molecular geometry that is different from its electron-
group geometry?
A)
B)
C)
D)
Answer: B (
)
Reason: It has 4 electron groups (Tetrahedral), but only 3 are bonds and 1 is a lone
pair, making the molecular geometry Trigonal Pyramidal.
2. What are the ideal bond angles in
?
A)
B)
C)
D)
Answer: C (
)
Reason:
has 6 electron groups (1 lone pair, 5 bonds), which is an Octahedral arrangement.
Lone pair repulsion will actually make the angles slightly
.
Chem 103
, Chem 103
3. Identify the molecular geometry of
(the triiodide ion).
Answer: Linear
Reason: The central Iodine has 3 lone pairs and 2 bonds (5 electron groups). The 3
lone pairs occupy the equatorial positions of a trigonal bipyramid, leaving the
atoms in a straight line (
).
Part 2: Polarity & Formal Charge
4. Based on formal charge, which is the most stable Lewis structure for
?
A)
B)
C)
Answer: B (
)
Reason: This structure places the negative formal charge on the Oxygen atom (the
most electronegative element in the molecule).
Chem 103
Chem 103 Exam 3 Questions and Answers Top
Graded 2026
Part 1: Molecular Geometry & VSEPR
1. Which molecule has a molecular geometry that is different from its electron-
group geometry?
A)
B)
C)
D)
Answer: B (
)
Reason: It has 4 electron groups (Tetrahedral), but only 3 are bonds and 1 is a lone
pair, making the molecular geometry Trigonal Pyramidal.
2. What are the ideal bond angles in
?
A)
B)
C)
D)
Answer: C (
)
Reason:
has 6 electron groups (1 lone pair, 5 bonds), which is an Octahedral arrangement.
Lone pair repulsion will actually make the angles slightly
.
Chem 103
, Chem 103
3. Identify the molecular geometry of
(the triiodide ion).
Answer: Linear
Reason: The central Iodine has 3 lone pairs and 2 bonds (5 electron groups). The 3
lone pairs occupy the equatorial positions of a trigonal bipyramid, leaving the
atoms in a straight line (
).
Part 2: Polarity & Formal Charge
4. Based on formal charge, which is the most stable Lewis structure for
?
A)
B)
C)
Answer: B (
)
Reason: This structure places the negative formal charge on the Oxygen atom (the
most electronegative element in the molecule).
Chem 103
