Worksheet: Lewis Structure, Resonance, VSEPR, Molecular Polarity
MULTIPLE CHOICE.
1) What is the number of valence electrons in a molecule of carbon dioxide?
A) 24
B) 16
C) 12
D) 10
1)
2) The total number of valence electrons in a phosphate ion is
A) 29
B) 60
C) 32
D) 26
2)
3) Which of the following Lewis structures does NOT fulfill the octet rule?
. .
. .
A) H : O : C : : O :
B) H : C :: N :
· · · ·
· ·
H
. .
C) H : C : : O :
· ·
H
3)
. .
. .
D) : F : C : : C : F :
· · · ·
· · · ·
H
H
4) How many VSEPR electron groups are on the central atom in the Lewis structure
. .
H : C : : O :
· ·
H
A) 4
B) 2
C) 3
4)
D) 1
5) According to VSEPR theory, predict which of the following triatomic molecules is bent
. .
. .
. .
. .
. .
. .
. .
A) H : O : H
B) : O : : C : : O :
C) : S : : C : : S :
D) : O : : C : : S :
· ·
5)
6) For a molecule AX3 with four VSEPR electron groups on the central atom A, the bond angle
∠X-A-X is closest to
A) 90°
B) 180°
C) 120°
D) 109.5°
6)
7) The molecule AXY with four VSEPR electron groups on the central atom A would look like which
one of the following
7)
A)
B)
C)
D) none of the above
1
. . . .
. .
8) The molecular geometry of the molecule with a Lewis structure as : Cl : N : F :
· · · · · ·
H
8)
A) trigonal pyramidal
B) linear
C) bent
D) trigonal planar
E) tetrahedral
9) Which of the following molecules is nonpolar?
A) HCN
B) H2 O
9)
C) HCl
D) CO 2
PROBLEMS. Show work with proper Significant Figures and Units to receive credit.
10) Write two resonance structures for HCO2 - (central C atom)
11) (a) Name compound Br 2 O7 ; (b) Write formula for sulfur tetrafluoride and dichlorine hexachloride
12) Answer the questions by filling the spaces. 1 pt for each space unless otherwise stated. (H 2 O is used as an
example).
Molecules
H2 O (example)
Sum of all
valence
electrons
8
Lewis structure
(3 pts each)
PF4 +
COCl 2
. .
H : O : H
· ·
Bond polarity
C-O:
Note: nonpolar
O-H: polar
C-F:
△EN ≤ 0.4
Number of
VSEPR groups
4
on central atom
Molecular
bent (angular)
geometry
Bond angle
∠H-O-H =
109.5°
Molecular
polarity
polar
P-F: skip
2