Atomic Particle Worksheet
Complete the chart by filling in the missing information. Assume neutral atoms.
Name of element
Carbon-12
Helium-4
Zinc-65
Gold-197
Oxygen-16
Isotope
Symbol
12
C
6
Atomic
Number
Mass
Number
Number of
protons
Number of
Electrons
Number of
Neutrons
6
12
6
6
6
𝟒
𝟐𝑯𝒆
2
4
2
2
2
𝟔𝟓
𝟑𝟎𝒁𝒏
30
65
30
30
35
𝟏𝟗𝟕
𝟕𝟗𝑨𝒖
79
197
79
79
118
8
16
8
8
8
16
O
8
Lead-207
𝟐𝟎𝟕
𝟖𝟐𝑷𝒃
82
207
82
82
125
Iodine-127
𝟏𝟐𝟕
𝟓𝟑𝑰
53
127
53
53
74
Potassium-39
𝟑𝟗
𝟏𝟗𝒁𝒏
19
39
19
19
20
Atomic Mass Problems
1. Calculate the average atomic mass of sulfur if 95.00% of all sulfur atoms have a mass of 31.972 amu,
0.76% has a mass of 32.971amu and 4.22% have a mass of 33.967amu.
(0.9500 x 31.972amu) + (0.0076 x 32.971amu) + (0.0422 x 33.967amu) = 32.06amu
2. There are three isotopes of silicon. They have mass numbers of 28, 29 and 30. The average atomic
mass of silicon is 28.086amu. What does this say about the relative abundances of the three
isotopes?
The isotope with a mass number of 28 is the most abundant isotope because the atomic mass
of is closest to 28.
3.
The atomic mass of bromine is 79.904amu. One isotope of bromine has an atomic mass of
78.92amu and a relative abundance of 50.69%. The other major isotope of bromine has an atomic
mass of 80.92amu. What is the relative abundance of the second isotope?
79.904amu = (0.5069 x 78.92amu) + (x x 80.92amu)
x = 49.31%
Nuclear Decay Reactions
Complete the following nuclear equations and state the type of nuclear decay.
Po  _______  24 He
1.
210
84
2.
8
5
3.
_______ 
4.
14
6
206
82𝑃𝑏 –
B  48 Be  _______
234
91
𝟎
+𝟏𝜷
Pa  e  
0
1
C  _______  e
5. ______ 
81
37
𝟏𝟒
𝟕𝑵
Rb  3681Kr + X-ray photon
O  157 N  ______
6.
15
8
7.
58
28
8.
226
88
9*
1
0
10.
238
92
Ni  e  _______
0
1
Ra 
222
86
– positron emission
𝟐𝟑𝟒
𝟗𝟎𝑻𝒉
0
1
Rn  ______  
𝟎
−𝟏𝜷–
electron capture
𝟎
+𝟏𝜷
– positron emission
58
27
Co – electron capture
𝟏
𝟏𝒑
U  _______  24 He
– beta and gamma decay
– beta decay
𝟒
𝟐𝑯𝒆–
n  _____  10 e
alpha decay
alpha decay
– beta decay
𝟐𝟑𝟒
𝟗𝟎𝑻𝒉
– alpha decay
Complete the following nuclear equations.
9
4
Be  24 He  _____  01n
F  178 O  _____
( 𝟏𝟏𝑯)
H  _____  24 He  01n  energy
( 𝟑𝟏𝑯)
( 𝟏𝟐𝟔𝑪)
20.
18
9
( 𝟐𝟑𝟗
𝟗𝟑𝑵𝒑)
21.
2
1
( −𝟏𝟎𝜷)
22.
27
14
30
Al  ______  14
Si  11H
( 𝟒𝟐𝑯𝒆)
23. ______  2 He 
Ba  ______  10 e
( 𝟏𝟒𝟏
𝟓𝟕𝑳𝒂 )
24.
32
15
16. ______  2 He  8 O  1 p
( 𝟏𝟒𝟕𝑵)
25.
142
61
17. ______ 
( 𝟏𝟖𝟓
𝟕𝟗𝑨𝒖)
26.
14
7
( 𝟒𝟐𝑯𝒆)
27.
13
6
Cf  n ( 𝟐𝟑𝟖
𝟗𝟐𝑼)
28.
239
94
11.
12. ______ 
Cu 
13.
66
29
14.
27
13
15.
141
56
66
30
239
94
Pu  10 e
Zn  ______
4
18.
241
95
17
181
77
1
Ir  24 He
Am  _____  237
93 Np
19. ______  6 C 
12
246
98
Si  10 e  ______
4
210
81
Tl
The alpha decay of iridium-174
𝟏𝟕𝟒
𝟕𝟕𝑰𝒓
2)
 𝟒𝟐𝑯𝒆+
The beta decay of platinum-199
𝟏𝟗𝟗
𝟎
𝟕𝟖𝑷𝒕 −𝟏𝜷
3)
+
𝟏𝟗𝟗
𝟕𝟗𝑨𝒖
Positron emission from sulfur-31
𝟑𝟏
𝟏𝟔𝑺
4)
𝟏𝟕𝟎
𝟕𝟓𝑹𝒆
 +𝟏𝟎𝜷 +
𝟑𝟏
𝟏𝟓𝑷
Krypton-76 undergoes electron capture
𝟕𝟔
𝟑𝟔𝑲𝒓
+
𝟎
−𝟏𝒆

𝟕𝟔
𝟑𝟓𝑩𝒓
( 𝟐𝟏𝟒
𝟖𝟑𝑩𝒊)
P  ______  10 e
( 𝟑𝟐
𝟏𝟔𝑺)
Pm  _____  142
60 Nd
( −𝟏𝟎𝜷)
N  _____  146 C  11 p
( 𝟏𝟎𝒏)
C  01n  ______
( 𝟏𝟒𝟔𝑪)
Pu  24 He  11H  2 01n  ______ ( 𝟐𝟒𝟎
𝟗𝟓𝑨𝒎)
Using your knowledge of nuclear chemistry, write the equations for the following processes:
1)
( 𝟐𝟕
𝟏𝟓𝑷)
Half Life Problems
1) A certain isotope has a half-life of 6.00 hours. How much of a 5.00g sample will be left after 24
hours?
24 hours / 6.00 hours = 4.00 = n
initial= (5.00 g)(1/2)4.00 = (5.00 g)(1/16) = 0.3125 g = 0.313 g
2) A certain isotope has a half-life of 3.25 hours. How much of a 10.0kg sample will be left after 3 days?
3.25 hours / 24 hours = 0.135416667 days
3 days / 0.135416667 days = 22.15384615 = n
final= (10.0 g)(1/2)22.15384615 = 0.000002143 g = 0.00000214 g
3) Carbon-14 has a half-life of 5730 years. How long will it take for a 1.00kg sample to be reduced to
0.25kg of carbon-14?
(0.25 kg) / (1.00 kg) = 0.25 = (1/2)n
n=2
2.0 = TE / 5,730 years
TE = (2.0)(5,730 years) = 11, 460 years = 11,000 years
4) A certain isotope of Uranium has a half-life of 4.3 billion years. How long will it take for a 2.7g sample
to be reduced to 0.0844g?
(0.0844 g) / (2.7 g) = 0.0312592593 = (1/2)n
n = ln(0.0312592593) / ln (1/2) = 4.999572598
4.999572598 = TE / 4.3x109 years
TE = (4.999572598)(4.3x109 years ) = 2.149816217x1010 years = 2.1x1010 years
5) A 0.40g sample of thorium-228 is reduced to 0.05g in 5.7 years. What is the half-life of thorium-228?
(0.05 g) / (0.40 g) = 0.125 = (1/2)n
n = ln(0.125) / ln(1/2) = 3
3 = 5.7 years / T
T = 5.7 years / 3 = 1.9 years = 2 years
6) A sample of radon-222 is found to have decreased from 266g to 8.5g in 19 days. Calculate the halflife of radon-222.
(8.5 g) / (266 g) = 0.0319548872 = (1/2)n
n = ln(0.0319548872) / ln(1/2) = 4.967819594
4.967819594 = 19 days / T
T = 19 days / 4.967819594 = 3.824615536 days = 3.8 days
7) An isotope with a half-life of 8 hours was received exactly 24 hours before it was to be used. At the
time of use, the quantity of the isotope was 16.5g. How much of the isotope was there upon delivery
to the lab?
24 hours / 8 hours = 3 = n
16.5 g =(1/2)3
x
mi = (16.5 g) / (1/8) = 132 g
8) How long will a 12.4g sample of a radioisotope take to decay to 1.55g if its half-life is 1.2 days?
(1.55 g) / (12.4 g) = 0.125 = (1/2)n
n =3
3.00 = TE / 1.2 days
TE = (3.00)(1.2days) = 3.6 days
Induced Transmutation Reactions
Write the following reactions from the given information
1. Alpha particle bombardment of einsteinium-253 (one of the products is a neutron).
𝟐𝟓𝟑
𝟗𝟗𝑬𝒔
2.
𝟐𝟓𝟔
𝟏𝟎𝟏𝑴𝒅
Induced transmutation of uranium-238 into californium-246 by bombardment with carbon-12.
𝟐𝟑𝟖
𝟗𝟐𝑼
3.
+ 𝟒𝟐𝑯𝒆 + 𝟏𝟎𝒏 +
+
𝟏𝟐
𝟔𝑪

𝟐𝟒𝟔
𝟗𝟖𝑪𝒇+
4 𝟏𝟎𝒏
One induced transmutation reaction of uranium-235 with a neutron results in the release of three
neutrons and the production of two new nuclides. One of the nuclides is xenon-138. Write the equation
with both reactants and all three products.
𝟐𝟑𝟓
𝟏
𝟗𝟐𝑼+ 𝟎𝒏
 3 𝟏𝟎𝒏+
𝟏𝟑𝟖
𝟗𝟓
𝟓𝟒𝑿𝒆+ 𝟑𝟖𝑺𝒓
4. Bombardment of uranium-235 with a neutron can generate tellurium-135, 3 neutrons, and one other
product. Write the complete reaction for this transmutation.
𝟐𝟑𝟓
𝟏
𝟗𝟐𝑼+ 𝟎𝒏
3 𝟏𝟎𝒏+
𝟏𝟑𝟓
𝟗𝟖
𝟓𝟐𝑻𝒆+ 𝟒𝟎𝒁𝒓
5. The first radioactive nucleus produced in the laboratory was phosphorus-30. Another product of this
reaction was a neutron. This was accomplished through alpha bombardment. Write the complete
transmutation reaction including original isotope.
𝟒
27
𝟐𝑯𝒆+ 13
Al 
𝟑𝟎
𝟏
𝟏𝟓𝑷+ 𝟎𝒏
6. When sodium-23 combines with hydrogen-2, an alpha particle is produced along with a new nuclide.
Write the complete equation for this fusion reaction.
23
11
Na + 21 H  𝟒𝟐𝑯𝒆 +
𝟐𝟏
𝟏𝟎𝑵𝒆