CHM1020 (Shah)
Prince George’s Community College
EXAM 3 (100 points)
1) Which of the following represent the Lewis structure for Ca2 ⁺ ?
A)
Answer: E
B) ) D) E)
2) Which of the following represent the Lewis structure for S2 ⁻ ?
A)
Answer: A
B) C) D) E)
3) Use Lewis theory to determine the chemical formula for the compound formed between Ca and N.
A) CaN B) Ca3N2 C) CaN2 D) Ca2N E) Ca2N3
Answer: B
4) Give the complete electronic configuration for Br-.
A) 1s22s22p63s23p64s24p6
B) 1s22s22p63s23p64s24d104p6
C) 1s22s22p63s23p64s23d104p6
D) 1s22s22p63s23p64s23d104p5
Answer:
5) Determine the electron geometry (eg) and molecular geometry (mg) of PF5.
A) eg=trigonal bipyramidal, mg=trigonal bipyramidal
B) eg=octahedral, mg=octahedral
C) eg=trigonal bipyramidal, mg=tetrahedral
D) eg=tetrahedral, mg=trigonal pyramidal
E) eg=trigonal planar, mg=octahedral
Answer: A
6) Determine the electron geometry (eg) and molecular geometry (mg) of NCl3.
A) eg=tetrahedral, mg=tetrahedral
B) eg=linear, mg=trigonal planar
C) eg=trigonal planar, mg=bent
D) eg=linear, mg=linear
E) eg=tetrahedral, mg=trigonal pyramidal

Answer: E
7) Determine the electron geometry (eg) and molecular geometry (mg) of XeF2.
A) eg=trigonal bipyramidal, mg=bent
B) eg=linear, mg=linear
C) eg=tetrahedral, mg=linear
D) eg=trigonal bipyramidal, mg=linear
E) eg=tetrahedral, mg=bent
Answer: D
8) Determine the electron geometry (eg) and molecular geometry (mg) of XeF4.
A) eg=tetrahedral, mg=tetrahedral
B) eg=linear, eg=linear
C) eg=tetrahedral, mg=bent
D) eg=trigonal bipyramidal, mg=tetrahedral
E) eg=octahedral, mg=square planar
Answer: E
9) A molecule containing a central atom with sp3d hybridization has a(n) __________ electron geometry.
A) tetrahedral B) linear C) octahedral D) trigonal planar
E) trigonal bipyramidal
Answer: E
10) Draw the Lewis structure for OF2. What is the hybridization on the O atom?
A) sp B) sp3 C) sp2 D) sp3d E) sp3d2
11) Draw the Lewis structure for the molecule CH2CHCH3. How many sigma and pi bonds does it contain?
A) 8 sigma, 1 pi B) 9 sigma, 0 pi C) 9 sigma, 1 pi
D) 7 sigma, 2 pi
Answer: A
E) 8 sigma, 2 pi
12) What is the strongest type of intermolecular force present in H2?
A) ion-dipole B) dipole-dipole
Answer: C
C) dispersion D) hydrogen bonding
13) What is the strongest type of intermolecular force present in CHF3?

A) ion-dipole B) dispersion C) hydrogen bonding D) dipole-dipole
Answer: D
14) What is the strongest type of intermolecular force present in NH2CH3?
A) dispersion B) dipole-dipole
Answer: C
C) hydrogen bonding D) ion-dipole
15) Place the following compounds in order of decreasing strength of intermolecular forces.
HF O2 CO2
A) HF > CO2 > O2
C) O2 > CO2 > HF
E) CO2 > O2 > HF
B) HF > O2 > CO2
D) CO2 > HF > O2
Answer: A
16) Identify the compound that does not have hydrogen bonding.
A) (CH3)3N B) H2O C) CH3OH D) HF E) CH3NH2
17)
Answer: A
Which of the following compounds exhibits only dispersion and dipole-dipole intermolecular interactions?
A) H2 B) HI C) CO2 D) CH3NH2
Answer: B
18) Which of the following statements is TRUE?
A) An ionic bond is much stronger than most covalent bonds.
B) An ionic bond is formed through the sharing of electrons.
C) Ionic compounds at room temperature typically conduct electricity.
D) Once dissolved in water, ionic compounds rarely conduct electricity.
E) None of the above are true.
Answer: A
19) Identify the substance that conducts electricity.
A) NaCl dissolved in water B) solid NaCl C) water
E) sugar dissolved in water.
Answer: A
D) solid sugar

20) Place the following elements in order of increasing electronegativity.
K Cs P
A) P < K < Cs
Answer: D
B) K < P < Cs C) Cs < P < K D) Cs < K < P
1.
Explain an appropriate chemical bond in each of the following compounds/molecules. (10)
Na
2
S H
2
O
2
SbCl
3
GaH
3
CS
2
2.
Write EG, MG, bond angle, Polar or Nonpolar, hybridization, number of sigma bonds, and number of pi bonds around central atom in the following molecules or ions.
(20 points) a.
H
2
Se b.
TiCl
4

c.
XeO
4 d.
SCN e.
CH
3
COOH
3.
Draw the Lewis structures and calculate the formal charges for each atom. (10) a.
C
2
H
5
Cl b.
PCl
3

c.
CO d.
SeOCl
2
4.
A. Draw the possible Lewis structure and if they contain resonance forms, write all resonance structures. (5) a.
CO
3
2b.
HCO
2
-
B.
Identify intermolecular forces in the following: (5) a.
CHCl
3 b.
O
2 c.
C
2
H
6

d.
e.
CH
SO
3
2
OH
5.
True or False (10) a.
The ability of an atom to attract electrons to itself in a chemical bond is called electronegativity. b.
In metallic bond, electrons pooled between metal and nonmetal. c.
In C
2
H
4
molecule, there are 5 sigma bonds and only one pi bond. d.
Average bond energy for double bond between carbon and carbon is higher than triple bond between carbon and carbon. e.
Triple bonds are shorter than double bonds.