Name ___________________________
Class __________________
Date ____________
Chapter 39 The Atomic Nucleus and Radioactivity
Exercises
39.1 The Atomic Nucleus
(pages 783–784)
1. Circle the letter of each nucleon.
a. proton
b. neutron
c. electron
d. positron
2. Is the following sentence true or false? The mass of a proton and
false
an electron are nearly the same.
nucleus
3. Most of an atom’s mass is located in its
.
4. Describe the relationship between the number of protons and the
number of electrons in a neutral atom.
They are equal.
5. Circle the letter of the particle that determines the kind of element and
the chemical properties of an atom.
a. proton
b. neutron
c. electron
d. positron
6. Describe the primary role of the neutrons in the nucleus of an atom.
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They act as glue, holding the nucleus together.
7. Circle the letter that best describes the strong force.
a. an attractive magnetic force
b. a repulsive electric force
c. an attractive nuclear force
d. an attractive gravitational force
8. Is the following sentence true or false? The strong force acts across large
false
distances.
9. The two major forces that act on a nucleus are the strong force and
electrical forces .
protons
neutrons
to
to
10. A nucleus needs a certain ratio of
make it stable.
39.2 Radioactive Decay
(pages 785–786)
11. What will a lone neutron decay into?
a proton and an electron (plus an antineutrino)
12. Particles that decay spontaneously and emit particles and energy are
radioactive
said to be
.
13. Explain what is meant by saying that radioactivity is governed by massenergy equivalence.
Particles decay only when their combined products have less mass after decay than
before.
14. All atoms with atomic numbers greater than
one way or another.
83
decay in
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Name ___________________________
Class __________________
Date ____________
Chapter 39 The Atomic Nucleus and Radioactivity
15. Circle the letter of the name given to the charged particles and energy
emitted by an unstable nucleus.
a. radiation
b. Planck emission
c. transmutation
d. transuranium
16. Circle the letter of the type of radiation that has a positive charge.
a. alpha particle
b. gamma ray
c. neutrino
d. beta particle
17. Is the following sentence true or false? Gamma rays have no charge.
true
18. The types of radiation that are deflected by a magnetic field are
alpha particles
and beta particles .
19. Is the following sentence true or false? An alpha particle is identical to a
true
helium nucleus.
electron or beta particle
20. A(n)
is ejected from a nucleus when a
neutron is converted into a proton.
21. Is the following sentence true or false? Gamma rays have zero mass.
true
22. Compare and contrast gamma rays and visible light rays. How are they
similar? How are they different?
Both are massless photons; gamma rays have much greater energies and frequencies
than light rays.
39.3 Radiation Penetrating Power
(pages 786–787)
25. Based on the figure to the right, circle
the letter that correctly ranks the types of
radiation from least penetrating to most
penetrating.
a. alpha particles, gamma rays, beta particles
b. gamma rays, beta particles, alpha particles
c. alpha particles, beta particles, gamma rays
d. gamma rays, alpha particles, beta particles
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23. Is the following sentence true or false? Alpha, beta, and gamma radiation
false
have roughly equal abilities to penetrate matter.
speed
charge
24. Radiation with a large
and a small
will
have the greatest penetrating ability.
Name ___________________________
Class __________________
Date ____________
Chapter 39 The Atomic Nucleus and Radioactivity
26. Is the following sentence true or false? Gamma rays are not stopped
false
unless they directly strike a metal surface.
39.4 Radioactive Isotopes
(pages 788–789)
27. Circle the letter that best describes isotopes of an element.
a. same composition and chemical properties
b. differing composition and identical chemical properties
c. differing composition and differing chemical properties
d. same composition and physical properties
protons
in the
28. The atomic number of an atom is the number of
nucleus.
29. The atomic mass number of an atom is the total number of
nucleons
in the nucleus.
atomic mass
and the 1 is
30. In isotope notation form, the 2 in 12 H is the
atomic
number
the
.
31. Is the following sentence true or false? All isotopes are radioactive. false
39.5 Radioactive Half-Life
(pages 790–791)
32. Is the following sentence true or false? All radioactive nuclei decay at the
false
same constant rate.
33. Define half-life. the time needed for half of a radioactive sample to decay
Use the following graph to answer Questions 34 and 35.
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Rate of Decay of Radium
0.5 kg
0.25 kg
.125 kg
34. The boxes in the graph above represent how much of a sample of
radium has decayed over time. What is the half-life of radium?
1620 years
35. Insert the missing masses on the lines next to the vertical axis of the graph.
rate of decay
of a particular radioisotope is constant and not
36. The
affected by external conditions.
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Chapter 39 The Atomic Nucleus and Radioactivity
39.6 Natural Transmutation of Elements (pages 792–794)
37. What is transmutation?
Transmutation is when one element changes into another.
38. Circle the letter that describes how an atom changes when it undergoes
alpha decay.
a. its atomic number increases by 2
b. its atomic number decreases by 2
c. its mass number increases by 2
d. its mass number increases by 4
39. Circle the letter that describes how an atom changes when it undergoes
beta decay.
a. its mass number increases by 1
b. its atomic number increases by 1
c. its mass number decreases by 1
d. its mass number increases by 4
40. Is the following sentence true or false? Beta emission has almost no effect
true
on the mass of the nucleus.
41. Is the following sentence true or false? Radioactive nuclei always
decay down the periodic table, in the direction of decreased mass.
false
39.7 Artificial Transmutation of Elements
(page 795)
Ernest Rutherford
44. What is significant about all of the elements beyond uranium on the
periodic table?
They have all been made by artificial transmutation.
39.8 Carbon Dating
(pages 796–797)
carbon-12
45. Most of the carbon on Earth exists in the form of
.
46. Is the following sentence true or false? All living things contain both
true
carbon-12 and carbon-14.
47. How is the ratio of carbon-14 to carbon-12 in a living organism related to
the ratio of carbon-14 to carbon-12 in the atmosphere?
They are the same.
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42. Is the following sentence true or false? Transmutation can be forced to
true
occur in laboratory.
43. Who was the first person to transmute an element artificially?
Name ___________________________
Class __________________
Date ____________
Chapter 39 The Atomic Nucleus and Radioactivity
48. How do scientists figure out how long ago a plant or animal died using
carbon dating?
By measuring the C-14 to C-12 ratio in the remains and comparing it the ratio in the
atmosphere
49. Is the following sentence true or false? Archeologists use carbon dating
true
techniques on skeletons.
39.9 Uranium Dating
(page 798)
50. What is uranium dating?
a process of determining the age of very old nonliving objects using radioactive minerals,
such as uranium
51. How is the percentage of lead isotopes in an ancient uranium-bearing
rock related to its age?
as the age of the rock increases so does the percentage of lead isotopes
52. Circle the letter of the age of the oldest rocks on Earth that have been
dated using uranium dating.
a. 1.2 million years
b. 2.2 million years
c. 4.2 billion years
d. 12.2 billion years
39.10 Radioactive Tracers
(pages 798–799)
53. Describe what a tracer is.
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a small amount of radioactive isotope used to analyze biological and mechanical
processes
54. Describe two uses of radioactive tracers.
sample answers: in medicine to study digestion, to test engine wear, to trace leaks in
pipes, to study fertilizer uptake in a plant
39.11 Radiation and You
(pages 800–801)
55. What are three sources of natural background radiation?
cosmic rays, Earth minerals, and radon gas in the air
56. Is the following sentence true or false? Cosmic radiation is more intense
true
at lower elevations than at higher elevations.
57. Our bodies are bombarded most by massless chargeless particles called
neutrinos
.
58. Circle the letter of the most damaging form of radiation.
a. alpha particles
b. gamma rays
c. beta particles
d. positrons
59. Is the following sentence true or false? People who receive high doses
of radiation have shorter life expectancies than those who do not.
true
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