Name______________________________________________
Date____________________
Chapters 8/9 Review
1. Categorize the following substances as nonpolar, polar, or ionic:
a. CsF
ionic
d. LiCl
ionic
b. N2
nonpolar
e. O3
nonpolar
c. N2O
polar
f. CaH2
ionic
2. Using bond energies, determine the for the following reaction:
CH4(g) + 3 Cl2(g) → CHCl3(g) + 3 HCl(g)
H
= 4 (C–H) + 3 (Cl–Cl) – (C–H) – 3 (C–Cl) – 3 (H–Cl)
= 4 (413 kJ) + 3 (239 kJ) – (413 kJ) – 3 (339 kJ) – 3 (427 kJ)
= –342 kJ
3. The standard enthalpy of formation for NH3(g) is –46 kJ/mol. Use this and the values for the
NN and H–H bond energies to estimate the N–H bond energy.
½ N2 + 3/2 H2 → NH3
H = –46 kJ/mol
–46 kJ = ½ (N≡N) + 3/2 (H–H) – 3 (N–H)
–46 kJ = ½ (941 kJ) + 3/2 (432 kJ) – 3x
–1164.5 kJ = – 3x
x = 388 kJ/mol
4. For the following molecules:
a. ClO2–
b. N3–
a.
draw a Lewis dot structure
calculate formal charges
give the shape and hybridization for the central atom
show resonance structures where appropriate
c. SOCl2 (S is central atom)
d. SO3
e. CBrI3
f. KrF4O
bent, sp3
O–Cl–O
-1 +1 -1
b.
c.
[ N≡N–N ]– ↔ [ N=N=N ]– ↔ [ N–N≡N ]–
0 +1 -2
-1 +1 -1
O -1
O
Cl–S–Cl
↔
0 +1 0
d.
O +1
↔
↔
O=S–O
0 +2 -1
-1
0
O -1
↔
O–S=O
-1 +2 0
I
I –C– I
tetrahedral, sp3, all formal charges = 0
Br
f.
O -1
0 F
F 0
Kr
0 F
+1
F 0
trigonal pyramidal, sp3
Cl–S–Cl
0
O -1
-1 +2 -1
e.
-2 +1 0
all zero
O 0
O–S–O
Cl–S–Cl
linear, sp
square pyramidal, sp3d2
trigonal planar, sp2
5. Consider the hydrogen cyanide molecule, HCN. Draw the Lewis dot structure, then sketch
the molecule showing the orbitalsLabel the type of bond or ) formed by each orbital
overlap.

H–C≡N:

C
H

N

6. Organic compounds vary greatly in the way their C atoms bond to each other. In the
following compounds, they form a single ring. Draw a Lewis structure for each: (a) C3H4;
(b) C3H6; (c) C4H6; (d) C4H4.
H
(a)
(b)
C
H C C
H
H
H H
C
H
H C C
H
H
(c) H
H
H
C C
C C
H
H
(d)
H
C C
C C
H
H
H
H
7. Draw the molecular orbital energy level diagram for F2. Determine the bond order and
predict whether the molecule is paramagnetic or diamagnetic.
2p*
↓↑ ___
2p ___
↓↑ ___
↑
↓↑ ___
↓↑ ___
↑ 2p
2p* ___
2p
2p
2s*
2s ___
↓↑
↓↑ 2s
___
2s
bond order = (8 – 6) / 2 = 1
diamagnetic
8. Using the following information, draw the energy cycle for NaCl and determine its lattice
energy.
ionization energy of Na 496 kJ/mol
bond energy of Cl2 244 kJ/mol
electron affinity of Cl –349 kJ/mol
ΔH of sublimation for Na 108 kJ/mol
ΔHºf (NaCl) –411 kJ/mol
lattice energy = 411 kJ + 108 kJ + 496 kJ + 122 kJ – 349 kJ = –788 kJ
Na+(g) + Cl(g)
Na+(g)
–349 kJ
122 kJ
+ ½ Cl2(g)
Na+(g)
496 kJ
+
Cl–
(g)
Na (g) + ½ Cl2(g)
108 kJ
Na(s) + ½ Cl2(g)
lattice E
411 kJ
(changed sign)
NaCl(s)
This is absolutely NOT
drawn to scale!