Name________________________
Chemistry I-Honors
Atomic Theory and Nuclear Chemistry
Study Guide Solution Set
Date_______________
1. Matching
Match the following scientists (on the left) with his contribution (on the right) to the Modern Atomic Theory:
F
Democritus
H
Robert Millikan
E
Ernest Rutherford
B
J.J. Thomson
A. English physicist who was awarded the Nobel Prize for the discovery of the
neutron
B. Known for two contributions. Discovered the electron and formulated a
hypothesis for the atom which described a spherical positive charge
embedded with negative charges (electrons) which his contemporaries
called the plum pudding model for its weak scientific basis
C. Greek-Sicilian who originated the Cosmogenic Theory of the four classical
elements: Earth, Fire, Wind, and Water
D. English chemist who formulated the Five Main Points of Atomic Theory
G
Aristotle
E. New Zealander who discovered the proton through his gold foil experiment
A
James Chadwick
D
John Dalton
C
Empedocles
F. Greek philosopher who gave us the word atom from the Greek word
“atomos” meaning indivisible
G. Postulated the theory of the Continuity of Matter which described the
infinite divisibility of atoms
H. American scientist who discovered the charge of an electron through his oil
drop experiment.
2. Know the parts of the atom (protons, neutrons, & electrons)
A. Which are in the nucleus?
Protons and Neutrons
B. Which does not contribute to the mass of an atom?
electrons
C. What is the charge on each subatomic particle?
Proton (+), neutron (0), electron (-)
D. If an atom loses 3 electrons, what is its charge and name (cation or anion)?
E. How are isotopes of the same element different?
Mass and the number of neutrons
F. What fundamental particle did Rutherford use in his experiment?
3. Fill in the blanks below.
Isotope Name
# p+
# no
# e-
Iodine – 126
53
73
52
Selenium-79
34
45
36
Chromium – 53
24
29
24
Potassium – 40 (ion, 1+)
19
21
18
Tellurium – 130 (ion, 2-)
52
78
54
3+ , cation
Nuclear Symbol
𝟏𝟐𝟔
I
𝟓𝟑
𝟕𝟗
Se
𝟑𝟒
𝟓𝟑
Cr
𝟐𝟒
𝟒𝟎 +
K
𝟏𝟗
𝟏𝟑𝟎 2Te
𝟓𝟐
Alpha particle (α)
Atomic #
Mass #
53
126
34
79
24
53
19
40
52
130
-24.
104.07
A gaseous element has two isotopes: G-102 and G-108. The percent abundance of G-108 is
34.550%. What is the average atomic weight of element G?
(108)(0.34550) = 37.314
+ (102)(0.65450) = 66.759
___________________________
average at. wt. = 104.07
5.
80.13
Another element - Z - has three isotopes: Z-78, Z-81, and Z-82. The percent abundance of the
three isotopes are: Z-78 34.050%, Z-81 50.720%, and Z-82 15.230%. What is the average
atomic weight of element Z?
AAM =
6.
27.77%
78(0.34050) + 81(0.50720) + 82(0.15230) = 80.13
A certain element is known to contain two stable isotopes M-203 and M-205. If the
atomic mass of M-203 is 203.1022 amu and the atomic mass of M-205 is 205.1123 amu,
while the average atomic mass for this element is known to be 203.6604 amu, what is the
percent abundance of the heavier isotope?
203.6604 = 203.1022(1-x) + 205.1123(x)
x = 0.227697
% abundance = 27.77% (heavier isotope)
7.
3.91-mg
A radioactive isotope has a half life of 100 minutes. If there were 500 mg of the substance
originally, how much would be left after 700 minutes?
700mins / 100mins = 7 half-lives
500mg  250mg  125mg  62.5mg  31.25mg  15.625mg  7.8125mg  3.906mg
1
2
3
4
5
6
7
8. 1.72 x 104 years
A bone is found containing 35 mg of C-14. If it originally should have contained 280
mg and the half life of C-14 is 5730 years, how old is the bone?
280mg  140mg  70mg  35mg
3 half-lives pass
so, 3*5730 = 17200
9.
4 half-lives
How many half lives have occurred if there is 65 mg of a sample that originally
contained 1040 mg?
1040mg  520mg  260mg  130mg  65mg
4 half-lives
-310. Write what is produced as the following undergo alpha decay.
A.
211
Po  4He + 207Pb
B.
238
U  4He + 234Th
C.
241
Am  4He + 237Np
D.
239
Pu  4He + 235U
E.
60
Co  4He + 56Mn
11. Write the products as the following undergo beta decay.
A.
238
C.
56
Np 
-1β
B. 43 K  -1β + 43Ca
+ 238Pu
Fe  -1β + 56Co
D. 14 C  -1β + 14N
12. Fill in the missing piece of the following decay equations.
A.
156Nd

B.
13C
 4He +
C.
210
Pb 
D.
253
Es + 4He 
256Md
+
E.
239
Pu +
He 
230Am
+ 2 1n + 1H
0
-1 
0
4
-1 
+
+
156
9
Pm
Be
210Bi
1
n
13. Uranium- 238 combines with carbon-12 to make curium-246 and one other particle. Write the equation
for this process:
238U
+
12C

246Cm
+
4He
14. In the first steps of its radioactive decay series, thorium- 232 decays to radium-228. In the second step
the radium-228 then decays to actinium-228. Write the two equations for this decay series.
A.
232Th
B.
228Ra

228Ra
+
 228Ac +
4He
-1β
15. Challenge Problem:
A radioactive decay series begins with 237Np and ends with the formation of stable 209Bi. How
many alpha emissions (decays) and how many beta emissions (decays) are involved in the
sequence from one isotope to the other.
# alpha emissions:
7
# beta emissions:
4
-416. Consider the three fundamental particles below. Rank these particles in increasing order based on their
degree of penetrability. Draw a diagram indicating the individual degree of penetrability of these particles.
Be sure to include what materials can impede or retard these particles.
beta
alpha
gamma
Rank: alpha < beta < gamma
17. We have studied four types of nuclear reactions. List these four nuclear reactions and give an example of
each. You may use actual nuclear equations or you may describe each individually.
Type of Nuc. Rxn
fusion
fission
decay (spontaneous)
transmutation
Example
Explanation
27
12
39
Al +
C  K
13
6
19
238
4
144
98
U + He 
I + Nb
92
53
2
41
238
138
100

Sn +
Nb
92
50
42
14
4
17
1
N + He  O + H
8
7
2
1
multiple nuclei form a single product
one nucleus is broken into multiple (2 in this case) nuclei
by force (an alpha particle is used to break it up)
one nucleus is broken into multiple (2 in this case) nuclei
on its own. No force is needed.
one nucleus is transformed into another nucleus by
bombarding a particle into it. A particle may or may not be
emitted.
18.
C
Which of the following has 20 protons and 18 electrons?
2+
2+2
+1
2A) S ;
B) Ar ;
C) Ca ;
D) K ;
E) S
19.
D
An alpha particle is essentially:
A) an electron; B) a neutron; C) a proton;
D) a helium nucleus.
20.
B
Francium-212 undergoes beta radiation. The half-life of Fr-212 is 19.3 minutes. How many hours
does it take for a 9.000-gram sample of Fr-212 to decay until only 0.750 grams remains behind?
A) 57.9 hours
B) 1.15 hours
C) 32.0 hours
D) 2.34 hours
21.
C
Using the information from the question above, what is the resulting nucleus from this half-life?
A) Rn – 212;
B) Rn – 208;
C) Ra – 212;
D) Ra – 208;
E) At – 208.