Chemical Foundations Review Sheet (Chapter 3)
1. Give the chemical symbol for each of the following elements.
a. Sodium ___Na___
g. Copper __Cu___
b. Nickel
___Ni_____
h. Barium __Ba____
c. Potassium ___K___
i. Silver
__Ag____
2. Give the name for each of the following elements.
a. Si
_Silicon_____
f. Cs
___Cesium_____
b. Co
__Cobalt______ g. He
__Helium_____
3. Write the formula for each of the following substances, listing the elements in
the order given.
a. a molecule containing one phosphorus atom and three chlorine atoms
PCl3
b. a molecule containing two boron atoms and six hydrogen atoms
B2H6
c. a compound containing one calcium atom for every two chlorine atoms
CaCl2
d. a molecule containing one carbon atom and four bromine atoms
CBr4
e. a compound containing two iron atoms for every three oxygen atoms
Fe2O3
f. a molecule containing three hydrogen atoms, one phosphorus atom,
and four oxygen atoms.
H3PO4
4. How many protons and neutrons are contained in the nucleus of each of the
following atoms? Assuming each atom is uncharged, how many electrons are
present?
P
N
E
P
N
E
a. 244Pu
94 150 94
d. 133Cs
55 78 55
b. 241Am
95 146 95
e. 193Ir
77 116 77
227
c.
Ac
89 138 89
f. 56Mn
25
31 25
5. Write the atomic symbol ( AZ X) for each of the isotopes described below.
17O
Example: Z = 8, number of neutrons = 9
8
a. the isotope of chlorine in which A = 37
37Cl
b. Z = 27, A = 60
60Co
17
27
57Fe
c. number of protons = 26, number of neutrons = 31
26
131I
d. the isotope of I with a mass number of 131
53
7Li
e. Z = 3, number of neutrons = 4
3
6. Explain the difference between the mass number and average atomic mass.
Mass # is one isotope but AAM is all of the isotopes average
based upon percent abundance.
7. How did the outcome of Rutherford’s gold foil experiment indicate the
existence of a nucleus?
Must be a small dense positive charge because most of the alpha
particles went straight through and missed the positive charge.
8. Complete the following table.
Name
Symbol
Atomic
number
Mass
number
Number
of
Electrons
Number of
Neutrons
11
24
11
13
N0
7
14
7
7
Ba0
56
135
56
79
Sn4+
50
119
46
69
B
5
11
5
6
Cl
17
37
17
20
39 +
K
19
39
18
20
Cr3+
24
52
21
28
Li
3
10
3
7
N3-
7
14
10
7
Se2-
34
79
36
45
Sodium
24
Nitrogen
14
Barium
Tin
Na
135
119
Boron
11
Chlorine
37
Potassium
Chromium
52
Lithium
10
Nitrogen
14
Selenium
79
9. The element potassium consists of two isotopes: 40K, which has a mass of
40.01 amu and 39K which has a mass of 39.01 amu. The average atomic
mass of potassium is 39.31 amu. What is the percent abundance of each
of the isotopes?
40.01 (x) + 39.01 (100 –x) = 39.31
100
x = 70.0%
100-x = 30.0%
40K
39K
10. If element X consists of 32.0% of atoms with a mass of 48.0 amu each,
12.0% of atoms with a mass of 49.0 amu each, and 56.0% of the atoms
with a mass of 50.0 amu each, what is the atomic mass of element X?
32.0(48.0) + 12.0(49.0) + 56.0(50.0) = 49.24 amu
100