Unit 4:Physics
Science 10
Name: Block:
Book 3: radioactivty
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5.1 : Radioactivity & Nuclear Equations
Isotopes
_______________ are versions of an element with the same
______________________ but _________________________
Because the number of protons is the same for _________________________________,
it is the number of ______________ that determines the ________ of the isotope
Isotopes are commonly named by their ___________ and _____________________
Example: carbon-14 is an isotope
of _____________ with a mass
of _____. So, it has ______
protons and
________________ neutrons.
Standard Atomic Notation
Standard atomic notation (SAN) is how we represent different isotopes in nuclear reactions:
Practice: Write the following isotopes in standard atomic notation.
potassium-39 potassium-41
23892
U
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Subatomic Particles
Nuclear reactions also commonly include subatomic particles (______________________)
which can be shown in SAN.
Practice: Write the following subatomic particles in standard atomic notation.
neutron electron proton
How are Nuclear Reactions Different from Chemical Reactions?
Chemical reactions must obey the _________________________________________
Nuclear reactions ____________________ the law of conservation of mass because atomic
nuclei can _______ or _________ subatomic particles, including _______________ and
_____________, and become other _____________/______________ as a result
Nuclear reactions can also cause the transformation of tiny amounts of mass into __________
(usually heat), according to the famous equation:
energy = _____________________________
or, E = _______
The mass lost in this way is __________________ than a single subatomic particle, so the
total number of protons and neutrons _________________________
Nuclear Equations
The ___________ radioactive isotope that ____________ in a nuclear reaction is called the
_______________________, think of it like the ______________ in a chemical reaction
The ____________ isotope that ____________ from radioactive decay in a nuclear
reaction is called the _______________________, the _________ in a chemical reaction
Like chemical reactions, we can show the radioactive decay in nuclear reactions with nuclear
equations:
13153 I → 13154 Xe + 0−1β
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Rules for Completing Nuclear Reactions
We need to obey the following rules when completing nuclear equations:
1. The sum of the ____________________ cannot change: the total atomic mass in the parent
and daughter isotopes, and decay products must be equal.
2. The sum of the ____________________ cannot change: the total number of protons in the
parent and daughter isotopes, and decay products must be equal.
Alpha Particles
Radiation created when an unstable atom decays and releases a _____________________
is called an ____________________
Alpha particles are made up of _______________ and ________________, so they have a
___________________
Because they have 2 protons and _______ electrons, alpha particles have a ______ charge
We represent alpha particles with the Greek lower case letter alpha (_______) or ______ in
SAN:
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Example: Write an equation for the alpha decay of
uranium-238.
Beta Particles
Radiation created when a _______________ in an unstable atom decays and releases an
____________ is called a ____________________
The neutron is really converted into a ____________ and an ______________
The proton remains inside the _____________ and the electron is ____________
Because they are electrons, beta particles have ____ mass and a ______ charge
We represent beta particles with the Greek lower case letter beta (______) or ______ in
SAN:
Example: Write an equation for the beta decay of
mercury-201.
STEPS:
1. Write the parent isotope in SAN2. Put an arrow after the parent isotope3. Complete the daughter isotope as follows:
decrease the atomic number of theparent isotope by 2 and the decrease theatomic mass by 4. Then, find the newelement that you have created on theperiodic table (based on the atomicnumber), and add the symbol.
4. For the other product, add an alpha particlein SAN
5. Make sure that atomic masses and atomicnumbers are balanced.
STEPS:
1. Write the parent isotope in SAN2. Put an arrow after the parent isotope3. Complete the daughter isotope as follows:
increase the atomic number of theparent isotope by 1. Leave the massnumber unchanged. Then, find the newelement that you have created on theperiodic table (based on the atomicnumber), and add the symbol.
4. For the other product, add a beta particle inSAN
5. Make sure that atomic masses and atomicnumbers are balanced.
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Gamma Rays
Radiation created when an unstable atom releases __________________ as ___________
_____________________ is called _________________________
Atoms that release gamma rays do not give off ____________ or _____________, so the
________________________________________
Because they are a form of light, gamma radiation has an
________________________________________
(far smaller than we can measure in atomic mass)
We represent gamma radiation with the Greek lower case
letter gamma (______) in SAN:
Example: Write an equation for the gamma decay
of potassium-42.
Summary
Alpha Beta Gamma
Symbol
Description
Mass
Charge
Penetration
Look at your Data Page:
STEPS:
1. Write the parent isotope in SAN. Use anasterisk to denote that it is high energy.
2. Put an arrow after the parent isotope3. Complete the daughter isotope as follows:
keep it the same as the parent isotope(but no asterisk).
4. For the other product, add a gammaparticle in SAN
5. Make sure that atomic masses and atomicnumbers are balanced.
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Part 1 – Complete the table below.
Isotope Name Atomic Number Mass Number Number of
Protons Number of Neutrons
carbon-14
carbon-15
14 15
8 16
lithium-7
24 12
14 26
11 13
neon-22
19 40
Part 2 – Write each of the following isotopes in standard atomic notation.
Isotope Standard Atomic Notation Isotope Standard Atomic
Notation
helium-3 carbon-16
potassium-40 radium-226
chlorine-36 iodine-131
sodium-23 cobalt-52
Assignment #5.1: Complete the following worksheet in the space provided below
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Part 3 – Identify the following nuclear decay reactions as either alpha decay (AD), beta decay (BD), gamma decay (GD):
Reaction Decay Type
1. 22589 Ac → 22187 Fr + 42 α
2. 14662 Sm → 14663 Eu + 0−1𝛽𝛽
3. 23191 Pa → 22789 Ac + 42He
4. 6028Ni∗ → 00 𝛾𝛾 + 6028Ni
5. 209 F → _______ + 2010Ne
6. 5826Fe∗ → 5826Fe + _______
7. 2411Na → _______ + 209 F
Part 4 – Complete the following alpha decay reactions.
Reaction
8. 20884 Po → + 4
2 α
9. 21187 Fr → + 207
85 At
10. → 22187 Fr + 42 α
Part 5 – Complete the following beta decay reactions.
Reaction
11. → 5227Co + 0−1𝛽𝛽
12. 146 C → + 0
−1𝛽𝛽
13. 13153 I → 0−1 e +
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Part 6 – Complete the following gamma decay reactions.
Reaction
14. 14964 Gd∗ → + 0
0 γ
15. → 25498 Cf + 00 γ
16. 2412Mg∗ → + 0
0 γ
Part 7 – Complete the following decay reactions.
Reaction
17. 23191 Pa → + 4
2He
18. → 15266 Dy + 00 γ
19. 22688 Ra → + 4
2 α
20. 21684 Po → + 0
−1 𝛽𝛽
21. 4018Ar∗ → + 0
0 γ
22. → 23490 Th + 42He
23. → 0−1 e + 21282 Pb
24. → 0−1 𝛽𝛽 + 20181 Tl
25. 21483 Bi → + 4
2He
26. → 23491 Pa + 00 γ
27. → 2412Mg + 0−1 e
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Half-Life
The amount of time it takes for _______ of the radioactive nuclei in a sample to __________
is called its ____________________
Some isotopes decay at a ______ rate and have ______ half-lives
Example: U-238 = 4.5 billion years!)
Others decay at a _______ rate and have __________ half-lives
Example: Astatine-213 =125 nanoseconds)
Graphing Radioactive Decay
Half-lives Amount
Remaining
0
1
2
3
4
5 0
10
20
30
40
50
60
70
80
90
100
0 1 2 3 4 5
Am
oun
t re
mai
nin
g (%
)
Half-lives
5.2 : Half-life & Radioactive Dating
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Radioactive Dating: carbon-14
Living organisms contain ___________ amounts of carbon-14
When they die, the carbon-14 begins to ________ into _________________ with a
half-life of _________________
By analyzing how much carbon-14 remains in a sample ____________ to how much
carbon-12, you can accurately date the
organism’s ____________
After ______________ years so little
carbon-14 remains that dating becomes
______________
Radioactive Dating: potassium-40 Clock
When __________________ cools it contains a certain amount of radioactive
________________
Over time the potassium-40 _________ into ______________, with a half-life of
__________________________
The formation of these rocks can be
dated by sampling the _________ of
the two isotopes
Other isotope pairs allow us to
accurately date rocks that are
____________ or _______
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Solving Half-Life Problems
Half-life problems involve three variables:
1. _____________________________ of the parent isotope (0, 1, 2, etc.)
2. ___________ elapsed (hours, days, years)
3. __________ of the parent isotope remaining (g, kg, or %)
A half-life problem will identify _____ of the three, you
will need to calculate the third
Make sure that you ALWAYS ____________ for half-
life and time, and at ______ for the amount of the
parent isotope
Practice: If 50 grams of carbon-14 were present in a sample of bone, state how many grams would be
left after 17 190 years?
Half-Life Time Amount
0 0 100%
Half-life Time (years) Mass (g)
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Part 1 – Complete the following tables.
Half-life Percent of
parent isotope
Percent of daughter isotope
0
1
2
3
4
Part 2 – Half-Life Word Problems
1. A rock sample contains 120 g of a radioactive isotope. The radioactive isotope has a half-life of 5years. Complete the following table.
How many years have passed if there is only 7.5 g of the parent isotope left?
2. A 36 g sample of a radioactive isotope decayed to 4.5 g in 36 minutes. How much of the originalparent isotope would remain after the first 12 minutes?
Half-life Fraction of
parent isotope
Fraction of daughter isotope
0
1
2
3
4
Half-life Time (years) Mass (g) 0 0
1 5
2 10
3 15
4 20
5 25
Assignment #5.2: Complete the following worksheet in the space provided below
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3. The half-life of a particular radioactive isotope is 8 hours. What percent of the parent isotope wouldremain after 1 day?
4. A radioactive isotope sample has a half-life of 4 days. If 6 g of the sample remains unchanged after12 days, what was the initial mass of the sample?
5. A rock sample was dated using potassium-40. Measurement indicates that 1/8 of the original parentisotope is left in the rock sample. How old is the rock sample?
6. When a sample of lava solidified, it contained 28 g of uranium-238. If that lava sample was laterfound to contain only 7 g of U-238, how many years had passed since the lava solidified?
7. After 25 years, the number of radioactive cobalt atoms in a sample is reduced to 1/32 of the originalcount. What is the half-life of this isotope?
8. The half-life of Sr-90 is 28 years. If 80 g of Sr-90 is currently in a sample of soil, how much Sr-90will be present in the soil 84 years later?
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Fission:
The ______________ of a ______________________________________ into
____________________, ________________________, and ______________ is
called ______________
The two daughter isotopes of fission reactions are
usually __________, _______________ isotopes,
leading to other decay reactions
Fission equations have a __________________ and
a ____________ which triggers the decay in the
reactants, and ____________________________
in the products
Fusion
The _______________________ of ____________________
making a ___________ _________________ and
____________ is called ___________
The ___________ daughter isotope of fusion reactions is usually a
__________ isotope
Fusion equations have __________________ in the reactants, and a ________ element
plus ____________ in the products
Fusion reactions occur ______________ in the enormous _______ and _____________
inside of _________, beginning with the fusion of hydrogen atoms together to make helium
Completing Fission/Fusion Reactions
1. Total up the __________________ and _______________________ on _______
sides of the equation
2. The _______________ in the atomic numbers _______________ the unknown product,
look it up on the periodic table and write it in SAN
3. The difference in the ____________________ gives you the _____ of the unknown product
4. Rewrite finished equation and ___________ the number of particles emitted if necessary
5.3 : Nuclear Reactions
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Practice:
The Benefits of Using Nuclear Reactions
Fission reactions are used around the world inside of ____________________________,
generating _____________ without combustion or CO2, and radioactive ‘waste’ that is useful
in medicine for creating ____________ of internal organs
Fusion power plants exist but they currently require ________________ to run _________
_______________________
The Costs of Using Nuclear Reactions
Normal operation of fission power plants does not release radioactivity, but when they fail
__________________ can be released into the environment
Fission plants create ‘waste’ daughter isotopes that are also _______________ and must be
safely ____________ to avoid ___________________ the environment
Half-lives of these radioactive waste isotopes are ________________________________,
meaning that we will be dealing with them for many ________________
Fusion reactions result in _________ daughter isotopes (we would combine hydrogen to
make helium) which have _____ environmental effects; fusion technology would greatly
___________ the impact of generating electricity
Complete the following nuclear fission reaction: 10n + 23592 U → _____ + 9442Mo + 3 10n
Complete the following nuclear fusion reaction: 21H + 31H → _____ + 10n
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The Chernobyl Disaster
A catastrophic nuclear accident occurred in _________
in the _______________
A sudden surge of power caused a nuclear power plant to
__________ and burst into flames
____________ amounts of radiation were released
This caused many devastating ___________ and ______-
term effects, including ___________________ and
___________________
Currently, Chernobyl is ___________________, and is
not expected to be habitable for ______________ years.
Summary
Fission Fusion
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Identify each of the following nuclear reactions as either fission (FI), or fusion (FU), and then complete the reaction.
Reaction Reaction Type
1. 10n + 23592 U → __________+ 12 10n + 13654 Xe
2. 31H + 21H → 10n + __________
3. 23592 U + 10n → 14156 Ba + ______ 10n + 9236Ba
4. 10n + __________ → 6 10n + 14355 Cs + 9037Rb
5. 10n + 23592 U → 14354 Xe + 3 10n + __________
6. 21H + 21H → 10n + __________
7. 10n + 23592 U → __________ + 4 10n + 8032Ge
8. 21H + 63 Li → + __________ + 10n
9. __________ + 10n → 14054 Xe + 4 10n + 11346 Pd
10. 10n + 23592 U → 3 10n + __________ + 12753 I
11. 21H + 31H → __________+ 42He
12. 10n + 23592 U → 3 10n + 11549 In + __________
13. __________+ 10n → 13752 Te + 3 10n + 10042 Mo
14. 10n + 3517Cl → __________ + 21H
Assignment #5.3: Complete the following worksheet in the space provided below
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Vocabulary: Referring to your notes and textbook, define each of the following vocabulary terms in a complete sentence:
1. Alpha Particle
2. Beta Particle
3. Daughter Isotope
4. Fission
5. Fusion
6. Gamma Radiation
7. Half-Life
8. Isotope
9. Parent Isotope
Physics (Part 2) Unit Review Package
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Knowledge:
Write the following isotopes in standard atomic notation.
10. cobalt-60 11. barium-133 12. sodium-22
13. zinc-65 14. americium-241 15. hydrogen-3
16. Complete the following table describing the three types of radiation:
Alpha Beta Gamma
Symbol
Description
Mass
Charge
Identify each of the following nuclear reactions as alpha decay (AD), beta decay (BD), gamma decay (GD), fission (FI), or fusion (FU).
17. 20180
Hg → 20181
Tl + 0−1
β ____________
18. 10n + 235
92U → 139
50Tn + 94
42Mo + 3 1
0n
____________
19. 22589
Ac → 22187
Fr + 42α
____________
20. 23191
Pa → 42He + 227
89Ac
____________
21. 2411Na → 0
−1e + 24
12Mg
____________
22. 6028Ni* → 60
28Ni + 0
0γ
____________
23. 10n + 235
92U → 92
36Kr + 3 1
0n + 141
56Ba
____________
24. 21H + 6
3Li → 7
4Be + 1
0n
____________
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25. What are some important differences between chemical reactions and nuclear reactions?
Complete the following nuclear reactions. Be sure to show your work in the space provided.
26. 23892
U + 42He
_____________________________________________________________________
27. 2411Na + 0
−1e
_____________________________________________________________________
28. 10n + 235
92U → + 3 1
0n + 77
34Se
_____________________________________________________________________
29. 4019K + 0
−1β
_____________________________________________________________________
30. 32He + 0
0𝛾
_____________________________________________________________________
31. 42He + 28
12Mg
_____________________________________________________________________
32. 4621Sc + 4
2α
_____________________________________________________________________
33. 10n + 235
92U → 93
40Zr + + 3 1
0n
_____________________________________________________________________
34. 10n + 235
92U → + 3 1
0n + 105
46Pd
_____________________________________________________________________
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35. Describe the disadvantages and advantages of using fission reactions to generate electricity.
36. At right is the decay curve for potassium-40 and itsdaughter isotope argon-40. You analyse a sample ofvolcanic rock and find 10% potassium-40 compared to90% argon-40. How long ago were these rocks formed?Explain your answer.
37. If a rock originally contains 100 g of a radioactiveisotope, how much will be left after 3 half-lives? Show your work.
38. A bone contains 20g of a radioactive isotope that has a half-life of 1000 years. How much will beleft after 2000 years? Show your work.
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39. If a rock has only 20 g of radioactive isotope remaining after 3 half-lives, how much was there tostart with? Show your work.
40. Carbon-14 has a half-life of 5730 years. How much of an original sample weighing 80 g would beleft after 22,920 years? Show your work.
41. You weigh a sample of unknown radioactive material and find that it weighs 50 kg. If the sampleoriginally weighed 200 kg, and is now 2.6 billion years old, identify its half-life and the parentisotope. Show your work.
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