CHEM 1014
Exam III
John III. Gelder
November 18, 1999
Name ________________________
TA's Name ________________________
Lab Section _______
INSTRUCTIONS:
1. This examination consists of a total of 7 different pages.
The last page includes a periodic table and some useful
information. All work should be done in this booklet.
2. PRINT your name, TA's name and your lab section
number now in the space at the top of this sheet. DO
NOT SEPARATE THESE PAGES.
3. Answer all questions that you can and whenever called
for show your work clearly. Your method of solving
problems should pattern the approach used in
lecture/discussion. You do not have to show your work
for the multiple choice (if any) or short answer
questions.
4. Point values are shown next to the problem number.
5. Budget your time for each of the questions. Some
problems may have a low point value yet be very
challenging. If you do not recognize the solution to a
question quickly, skip it, and return to the question after
completing the easier problems.
6. Look through the exam before beginning; plan your
work; then begin.
7. R e l a x and do well.
SCORES
Page 2
Page 3
Page 4
Page 5
Page 6
TOTAL
_____
(29)
_____
(20)
_____
(25)
_____
(16)
_____
(10)
______
(100)
CHEM 1014 EXAM III
(5)
PAGE 2
1. Complete the following table
Substance
# valence electrons
K
1
S
6
Ag
1
N3–
8
Na+
8
(10) 2. Predict the formula of the compound formed between the following pairs of elements.
a)
Mg and O2
MgO
b)
Al and sulfur
Al 2 S 3
c)
potassium and bicarbonate
KHCO 3
d)
barium and sulfate
BaSO 4
e)
C and Cl2
CCl 4
(14) 3. Complete the following table;
Name of the compound
Formula of the compound
Sodium nitrite
NaNO 3
Barium hydroxide
Ba(OH)2
ammonia
NH 3
Lithium iodide
LiI
Zinc phosphate
Zn 3 (PO 4 ) 2
Sodium carbonate
Na2CO3
Magnesium sulfate
MgSO4
CHEM 1014 EXAM III
PAGE 3
(20) 4. Answer each of the following
a)
Provide a brief description of what is meant by the term cation.
A cation is an ion with a positive charge, it has fewer electrons than protons.
b)
Provide a brief description of what is meant by the term anion.
An anion is an ion with a negative charge, it has more electrons than protons.
c)
What kinds of compounds contain cations and anions?
Ionic compounds
d)
What is the name of the bond between cation(s) and anion(s)?
Ionic bonds
e)
What is the nature of the bond (attraction) in these compounds? (That is, what holds the ions
together to make the bond?)
Electrostatic attractions…attractions due to the opposite charges on the ions.
f)
An ion that we have not discussed in great detail is NH4+. Draw a Lewis structure of this
polyatomic ion.
g)
Write a formula for the compound of this ion combined with each of the ions Cl-, CO32-, PO43-.
NH 4 C l
(NH 4 ) 2 CO 3
(NH 4 ) 3 PO 4
h)
NH4+ is called the ammonium ion. Provide the name for each compound in g).
ammonium chloride
NH 4 C l
(NH 4 ) 2 CO 3 ammonium carbonate
(NH 4 ) 3 PO 4 ammonium phosphate
CHEM 1014 EXAM III
PAGE 4
(15) 5. Draw the Lewis structure for each of the following compounds/elements. (Show all bonding and
nonbonding electrons.)
a)
CHCl3
b)
OF2
c)
N2
d)
ONCl
e)
N 2H 4
(10) 6. What is the molecular geometry/shape of the following compounds. (Note: In the case of N2H4 provide
the molecular geometry around each nitrogen.)
Substance
Molecular geometry/shape
H 2S
bent
OF2
bent
CHCl3
tetrahedral
N 2H 4
pyramidal
H2CO
(Trigonal) planar
CHEM 1014 EXAM III
PAGE 5
(12) 7. Draw and name six structural isomers for the compound C7H16. (Be sure to clearly show all bonds
between carbon and hydrogen.)
n-heptane
2-methylhexane
3-methylhexane
3,3-dimethylpentane
2,2-dimethylpentane
CHEM 1014 EXAM III
PAGE 6
2,3-dimethylpentane
(4)
8. Are there any structural isomers of the compound C10H22 with a parent chain five carbons long? If so
draw an example and name the compound. If there are no structural isomers with a parent chain of five
carbons, briefly explain why.
2,2,3,3,4-pentamethylpentane
or
2-methyl-3,3-diethylpentane
CHEM 1014 EXAM III
(6)
PAGE 7
9. Name or draw the Lewis structure for the following organic compounds
3-methyl-4,4-diethylheptane
2,3,4-trimethylhexane
2,5-dimethylheptane
(4) 10. The equation for the formation of magnesium chloride is,
Mg(s) + Cl2(g) --> MgCl2(s)
We see the formula Cl2 appears on both sides of the equation. Using a diagram(s) or words explain the
difference in the bonding in the two substances containing chlorine.
In the reactants chlorine is in the elemental form with a covalent bond between the two
chlorine atoms.
In the product MgCl2 is an ionic compound. Although Cl2 is in the formula since the
compound is ionic MgCl2 contains ions…Mg2+ ion and 2 Cl- ions, there are no Cl2
molecules.
CHEM 1014 EXAM III
Periodic Table of the Elements
IA
1
VIIIA
1
2
H
He
1.008
3
2
PAGE 8
IIA
IIIA IVA VA VIA VIIA 4.00
4
Li Be
6.94 9.01
11
12
3
Na Mg
22.99 24.30
19
20
4
5
6
7
5
6
7
8
9
10
B
C
N
O
F
Ne
10.81 12.01 14.01 16.00 19.00 20.18
13
14
15
16
17
18
VIII
IIIB IVB VB VIB VIIB
21
22
K Ca Sc Ti
23
24
25
26
27
IB
28
Al
Si
P
S
Cl Ar
31
32
33
34
35
IIB 26.98 28.09 30.97 32.06 35.45 39.95
29
30
36
V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
39.10 40.08 44.96 47.88 50.94 52.00 54.94 55.85 58.93 58.69 63.55 65.38 69.72 72.59 74.92 78.96 79.90 83.80
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
Rb Sr
Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te
I
Xe
85.47 87.62 88.91 91.22 92.91 95.94 (98) 101.1 102.9 106.4 107.9 112.4 114.8 118.7 121.8 127.6 126.9 131.3
55
56
57
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
Cs Ba La Hf Ta W Re Os Ir
Pt Au Hg Tl Pb Bi Po At Rn
132.9 137.3 138.9 178.5 180.9 183.8 186.2 190.2 192.2 195.1 197.0 200.6 204.4 207.2 209.0 (209) (210) (222)
87
88
89 104 105 106 107 108 109
Fr Ra Ac Rf Db Sg Bh Hs Mt
(223) 226.0 227.0 (261) (262) (263) (262) (265) (266)
58
Lanthanides
59
60
61
62
63
64
65
66
67
68
69
70
71
Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
140.1 140.9 144.2 (145) 150.4 152.0 157.2 158.9 162.5 164.9 167.3 168.9 173.0 175.0
90
91
92
93
94
95
96
97
98
99 100 101 102 103
Actinides
Th Pa
U
Np Pu Am Cm Bk Cf Es Fm Md No Lr
232.0 231.0 238.0 237.0 (244) (243) (247) (247) (251) (252) (257) (258) (259) (260)
Useful Information