Honors Chemistry
Atomic Theory and Nuclear
Name______________________________
Atomic Theory
1. Complete the chart below given the following information:
Thompson’s charge to mass ratio = −1.76 x 108 C/g
Millikan’s charge of an electron = −1.6 x 10−19 C/e−
Millikan’s calculated mass of an electron = 9.1 x 10−28g/e−
Number of electrons
Mass of electrons (g)
Charge of electrons ( C )
5.0 x 10-5
5.0 x 1011
3.03 x 10-6
-7.04 x 109
1.00
1
4.6 x 1010
- 1.0
2
Isotopes
2. Distinguish between:
a. atomic number and mass number
b. average atomic mass and mass number
3. An isotope is found to have 7 protons and 7 neutrons. What is its
a. atomic number
b. mass number
c. isotopic symbol
4. Circle the symbols that are isotopes of one another.
24
12
52
6
a.
X b.
X c.
X d.
X
12
6
24
3
e.
24
X
11
f.
23
X
11
5. Write the isotope name (hyphen notation) for each element represented in question 4.
a. ________________________
b. _________________________
c. _________________________
d. __________________________
e. __________________________
f. ___________________________
6. Write the isotopic symbols for atoms with the following:
a. 9 p+ and 10 no ________________ b. 25 p+ and 30 no________________
c. 31 p+ and 39 no ________________ d. 1 p+ and 0 no __________________
7. A certain isotope of cobalt is five times as heavy as carbon-12. Write the name and symbol for
this isotope.
____________________________ ________________
8. In each of the following, information on two elements are provided. Given that information,
indicate if the two elements are isotopes of one another.
a. One element contains 22 protons and 24 neutrons while the other has 22 protons and 25
neutrons.
__________________
b. One element has 29 protons and 34 neutrons while the other has 30 protons and 34
neutrons.
__________________
c. One element has 24 protons and a mass number of 50 while the other element has an
atomic number of 24 and has 28 neutrons.
__________________
d. One element is neutral and has 78 electrons and 117 neutrons while the other neutral
element contains 79 electrons and 117 neutrons.
__________________
3
9. Complete the following chart:
a
Isotopic
Symbol
16
8O
#
neutrons
19
9F
rubidium-87
123
51Sb
nitrogen-15
h
i
#
electrons
oxygen-18
f
g
#
protons
40
20Ca
d
e
Mass
Number
manganese-56
b
c
Atomic
Number
Isotope Name
210
83Bi
27
j
32
15
k
32
l
7
72
13
m
19
n
51
o
Atomic Mass
10. Determine the average atomic mass of the following mixtures of isotopes.
a. 80.%
127
53 I ,
b. 50.%
197
79 Au ,
c. 15%
55
26 Fe ,
17%
126
53 I ,
50.%
85%
3%
198
79 Au
56
26 Fe
128
53 I
13
20
23
4
d. 99% 11 H , 0.8% 21 H , 0.2% 31H
e. 95%
14
7N,
3%
15
7N,
f. 98%
12
6C ,
2%
14
6C
2%
16
7N
g. Uranium has 3 isotopes with the following relative abundances: Uranium-234 (0.0058%),
U-235 (0.71%), and U-238 (99.23%). Calculate the average atomic mass of uranium:
Ions
11. An atom that loses electrons has a net __________ charge and is called a(n) _________________.
12. An atom that gains electrons has a net __________ charge and is called a(n) _________________.
13. When a sulfur-32 atom becomes an ion, it typically does so by gaining 2 electrons. What is the
isotopic symbol?
__________________
14. How many protons does Na+ have? ________ electrons? ________
15. How many electrons does P−3 have? ________ protons? _________
16. How many electrons does an ion have with an atomic number of 34 and a charge of −2? ________
5
17. Complete the following chart:
isotopic
symbol
a
b
atomic
number
mass
number
8
15
neutrons
charge
−2
24
d
25
e
26
g
electrons
63
+
29Cu
c
f
protons
13
22
27
10
13
10
32
40
83
80
126
Moles
18. How many moles of platinum are equivalent to 1.20 x 1024 atoms?
19. Calculate the mass in grams of 9.00 mol of potassium.
20. How many atoms are present in 8.00 mol of chlorine atoms?
21. How many atoms are present in 80.0 mol of zirconium?
+4
cation
or
anion?
6
22. Find the mass of 1625000 atoms of gold.
23. Determine the number of moles in 100. g of copper.
24. Calculate the number of atoms in 10.0 g of aluminum.
25. Determine the number of moles of helium in 10.0 g of helium.
26. Determine the mass in grams of 10.0 mol of bromine.
27. Determine the mass in grams of 5.00 x 1023 mol of oxygen atoms.
28. How many moles of iron are equivalent to 1.11x1025 atoms?
7
29. How many neutrons are in 3.26 mol of carbon-14 atoms?
30. How many electrons are in 0.653 mol of sodium ions?
31. How many protons are in 37 mg of tungsten atoms?
32. How many joules of heat are required to increase the temperature of 2.01 x 1023 atoms of tin from
13.5°C to 19.3°C?
33. How many moles of helium atoms must be present in a sample for the temperature to increase
11.3°C when 142.3 cal of thermal energy are added?
34. How many kJ of heat are required to melt a sample of gold containing 1.05 x 1023 atoms?
8
35. How many calories of heat are required to vaporize a sample of molten aluminum that contains
6.04 x 1022 Al atoms?
36. Krypton has a density of 3.74 g/L at STP. A flask contains 5.58 x 10−3 moles of Krypton atoms at
STP. What would the volume of the flask have to be to hold this sample at a pressure of 700.
mmHg and a temperature of 50.0°C?
37. The density of neon at STP is 0.902 g/L. A balloon contains 5.378 x 1022 Ne atoms at STP. What
would be the volume of the balloon if the pressure was doubled and the temperature was cut in
half?
Nuclear Equations
38. Fill in the blank with the isotopic symbol that will complete and balance the following nuclear
equations:
a. 21 H  21 H 
 11 H  ______
Cu 
b.
63
29
c.
241
95
1
1


Am
d. ______ 
e.
64
30
f.
235
92
Zn


H

U 
2
1
0
1
1
0
237
93
e
n
H
1
0

n
25
13
Al  _______
Np  _______






3
2
He

1
0
n
_______
138
56
Ba
 301 n
 _______
9
39. Write balanced nuclear equations for the following:
a. The alpha decay of neptunium-237
b. The beta decay of bismuth-210
c. The neutron bombardment of tin-120
d. The electron capture of iodine-128
e. The nuclear transmutation of mercury-201 that consists of two alpha decays and 1 beta
decay.
f. The electron capture of antimony-123 followed by the emission of 2 neutrons.
g. Alpha-particle bombardment of plutonium-239 produces a neutron and another isotope.
Write the nuclear equation for this reaction and identify the isotope.
h. When bombarded with a neutron, lithium-6 produces an alpha particle and an isotope of
hydrogen. Write the nuclear equation for this reaction. What isotope of hydrogen is
produced?
i. With what particle would you bombard sulfur-32 with to produce hydrogen-1 and
phosphorus-32? Write the appropriate nuclear equation.
j. With what particle would you bombard bismuth-209 to produce astatine-211 and 2
neutrons? Express this reaction in the form of a nuclear equation.
10
Half Life
40. A radioactive isotope of radon has a half life of 3.8 days. How long will it be before only 1/16 of
the original sample of radon remains?
41. A 1.000-kg block of phosphorus-32, which has a half-life of 14.3 days, is stored for 100.1 days.
At the end of this period, how much phosphorus-32 remains?
42. How much time will be required for a sample of radioactive tritium (t1/2 = 12.5 years) to lose 75 %
of its radioactivity?
43. A sample of air from a basement is collected to test for the presence of radon-222, which has a
half-life of 3.8 days. However, delays prevent the sample from being tested until 7.6 days have
passed. Measurements indicate the presence of 6.5 g of radon-222. How much radon-222 was
present in the sample when it was initially collected?
44. The half-life of carbon-14 is 5720 years. An artifact is found to contain 0.21 g of carbon-14.
Based on the quantity of carbon-12 present, it was determined that the sample, if new, would
contain 3.36g of carbon-14. How old is the sample?
45. A piece of wood is known to be 34,200 years old. At the present time, the wood contains 4.0 g of
carbon-14. How much carbon-14 was in the wood originally?
11
46. Gold-191 has a half-life of 12.4 hours. After one day and 13.2 hours, 10.6 g of gold-191 remains
in a sample. How much gold-191 was originally present in the sample?
47. There are 3.29 g of iodine remaining in a sample originally containing 26.3 g of iodine-126. The
half-life of iodine-126 is 13 days. How old is the sample?
48. A meteorite strikes the earth in western Wyoming. Chemical analysis shows that it contains 44.62
kg of radioactive iron-59 (t1/2 = 44.3 days). Approximately, how much of this isotope will remain
in the meteorite after 220 days?
49. A sample of pure radium-226 (t1/2 = 1620 yrs) is donated to a museum in the year 1990. The
sample weighs 5.0 mg. The museum decides to replace the sample after it has been reduced in
weight to 0.62 mg. In what year will the sample have to be replaced?
Review
50. Complete the table for the atoms indicated:
isotopic
symbol
name
atomic
number
mass
number
19
mercury-201
atomic
mass
electrons
10
protons
neutrons
8
10
12
51. Complete the table below:
Ion A
What is the atomic number?
What is the mass number
Ion B
13
33
How many protons?
How many electrons?
18
How many neutrons?
15
What is the charge?
+3
Write the isotopic symbol.
What kind of ion?
Change in electrons?
gain 2
52. A sample of neon gas is composed of 90.92 % neon-20, 0.257 % neon-21 and 8.82 % neon-22.
Calculate the atomic mass of neon. (show work)
53. How many atoms are in 2.89 moles of krypton?
54. How many grams of barium are in 0.548 moles of barium atoms?
55. How many moles of silicon are in 125.6 g Si?
13
22
56. How many grams of lithium are in a sample containing 2.3 x 10 Li atoms?
57. Write the nuclear equation for the:
a. beta decay of radium-226
b. alpha decay of protactinium-231
c. The electron capture of Uranium – 238
d. The transmutation of curium-247 beginning with a neutron bombardment followed by an
alpha decay.
58. What three conclusions were drawn from Rutherford’s experiment?
59. Cite 3 examples of the concepts learned in this chapter that can be used to dispute Dalton’s
Atomic Theory.
60. What device was Thomson using that led to the discovery of electrons?
14
61. An isotope of mass 42g is allowed to decay over time. After 27.4 days, the isotope had a mass of
5.25 g. What is the half life of this isotope?
62. What mass would the isotope described in the previous question have if it was allowed to sit for a
total of 11 half lives?
63. How many electrons would it take to have a combined mass of 1.77×10−5 g?
64. What is the mass and charge of 1.95 moles of electrons?
Cumulative Review
65. Determine the number of significant figures in each of the following:
a)
6.7090
b) 0.0384
c) 12,000
66. Three segments of a line are measured to be 12.5 mm, 1.1 in and 2.365 cm. What is the length of
the line?
67. Identify each of the following as a physical (P) or Chemical (C) change.
____ a) sodium chloride is dissolved in water
____ b) gasoline is burned in an automobile engine
____ c) water boils
____ d) when sodium iodide and lead sulfate are mixed, a yellow precipitate forms
15
68. Identify each of the following as an element (E), compound (C), Homogeneous mixture (Hom) of
Heterogeneous mixture (Het).
____ a) salt and water
____ d) sand and water
____ b) hydrogen
____ e) water
____ c) sodium chloride
____ f) uranium
69. A 16.3 gram sample of sulfur dioxide gas occupies 56.2 mL at a pressure of 772 mm and a
temperature of 95.6°C. What is the volume of the gas at STP?
70. A student measures the mass of an object as 135.80 g. Calculate the percent error in the
measurement, given that the accepted value for the mass is 137.23 g.
71. Convert 4.5 millimeters to kilometers. Express your answer in scientific notation.
72. Lead has a density of 11.4 g/cm3. How many atoms of lead are in 0.567 ft3 block of lead?
73. A 157 mg sample of helium at 22.5˚C absorbs 13.9 cal of heat energy. What will the temperature
of the helium be after it absorbs the energy?