Download Chapter 7 Worksheet

Science 10
Chapter 7 Worksheet
Chapter 7 – Atomic theory explains radioactivity.
Be sure to use the website at http://www.bcscience.com/bc10/pgs/links_u2.html and scroll down
to the Chapter 7 section.
Chapter 7.1 – Atomic Theory, Isotopes, and Radioactive Decay
1.
Radioactivity is the release of high-energy
a result of changes in the nuclei of its atoms.
2.
Natural background radiation
is the term for the radiation we come into contact everyday
that is all around us. Generally, since this type of radiation is always around us , it is viewed
as harmless .
3.
List the different types of waves/rays in the electromagnetic spectrum from lowest frequency/energy
to highest frequency/energy.
particles and energy
rays
from substance as
C Radiowaves, microwaves, infrared rays, visible light, ultraviolet rays, x-rays, and
gamma rays.
Visible light
4.
is the one form of radiation that humans can actually see.
Wilhelm Roentgen
discovered
x-rays
where the
x
5.
German physicist,
“unknown.”
stood for
6.
Marie Curie
and her husband Pierre Curie , with the help of the work of the French
physicist, Henri Becquerel , made huge advances in nuclear chemistry with their studies
concerning radioactivity.
7.
of
Isotope
the term given to different atoms of a particular element that have the same number
protons , but different numbers of
neutrons .
8.
The atomic number of an element is the same as the number of protons . The mass number of
an element represents the number of protons and neutrons added together.
9.
Describe how you can find how many neutrons are in a certain isotope of an element if the atomic
number is 52 and the mass number is 134.
C
C
C
C
Since the
The mass
134 = 52
So 134 -
atomic number = the # of protons, there are 52 protons in this isotope.
number equals the number of protons plus the number of neutrons.
+ the number of neutrons
52 = 82 neutrons.
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10. Standard atomic notation represents the chemical symbol
mass number
of a specific isotope.
, the
atomic number
and the
11. Describe the element, atomic number, number of protons, mass number, and number of neutrons for
the following standard atomic notation:
C
C
C
C
The
The
The
The
element is potassium.
atomic number and number of protons is 19.
mass number is 41.
number of neutrons is 41!19 = 22.
12. What do all isotopes of the same element have in common?
C Isotopes of the same element have the same element name, atomic number and
number of protons.
13. How do isotopes of the same element differ?
C Isotopes of the same element have different mass numbers and different number of
neutrons.
14. Complete the following table:
Isotope
Atomic Number
# Protons
Mass Number
# Neutrons
Carbon-13
6
6
13
7
Cobalt-27
27
27
59
32
Sodium-11
11
11
23
12
Arsenic-33
33
33
75
42
Chlorine-17
17
17
37
20
15. Radioactive atoms emit
radiation
because their nuclei are
unstable
.
16. The process in which unstable nuclei lose energy (thus gaining stability) by emitting radiation is
known as radioactive decay
.
17. Isotopes that are capable of radioactive decay are called
18. The three main types of emitted radiation are alpha
gamma
radiation. This was first discovered by
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radioisotopes
.
beta
radiation, and
Ernest Rutherford
.
radiation,
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19. Alpha radiation is a stream of alpha particles that have the same combination of particles as
the nucleus of a helium atom, with a mass number of 4 and an atomic number of 2 .
20. Alpha particles are made up of
2
2
protons and
neutrons.
21. Alpha particles are much larger than other types of radiation making them relatively
not highly penetrating
.
22. The term used to describe the emission of an alpha particle from a nucleus is
slow
and
alpha decay
.
23. Complete the following alpha decay problems:
a.
C
204
82
Pb
b.
C
221
87
Fr
c.
C
196
79
Au
24. A beta particle
is an electron. Electrons have a negligible mass that is approximately 0.0005
the mass of a proton or neutron, therefore electrons are assigned a mass of zero .
25. Beta particles (electrons) have a charge of
-1
.
26. During beta decay a neutron changes into a proton
process the proton stays in the nucleus while the
with a significant amount of energy.
electron
27. Since the only thing emitted during beta decay is an electron, the
unchanged and the atomic number increases by one.
28. A well-known beta decay reaction involves the
cancer of the thyroid gland.
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electron
and an
iodine-131
. During this
shoots out from the nucleus
mass number
remains
isotope used in the treatment of
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29. Complete the following beta decay problems:
a.
C
6
3
Li
b.
C
14
6
C
c.
C
24
12
Mg
30. Gamma radiation consists of high
energy
rays with a short
31. Gamma radiation has almost no mass
and no charge
the atomic number and mass number remain unchanged.
wavelength
.
, therefore during beta decay both
32. Gamma rays are one of the most dangerous forms of electromagnetic radiation; they have
much more energy that either
X-rays
or
UV rays .
33. Due to its insignificant size, gamma radiation
the three major types of radiation.
has the greatest
penetrating power
of
34. In gamma decay reactions equations we use the symbol (*) to represent that a certain nucleus has
extra energy .
35. Complete the following gamma decay problems:
a.
C
60
28
Ni
b.
C
42
19
K*
c.
C
24
11
Na
36. The symbol á is used to represent an
alpha
particle, the symbol â is used to represent
beta
particle and the symbol ã is used to represent a gamma particle.
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37. Alpha particles can be also be represented by a
represented by an electron .
38. In nuclear reaction equations, the
remain unchanged .
helium
total number
nucleus, and beta particles can also be
protons plus neutrons, and the charge number
Chapter 7.2 - Half-life
1. Carbon dating (also known as radiocarbon dating ) is the process of determining the age of
an object by measuring the amount of carbon-14 remaining in that object.
2.
Describe the process of carbon dating. How old can an object be to be used for carbon dating?
C Living objects have a nearly constant ratio between the carbon-12 and the
carbon-14 isotopes.
C Once an organism dies the ratio between the carbon-14 and carbon-12 isotope
decreases, which allows us to determine the age of a dead object.
C Only object that lived within the past 50,000 years can be used for carbon dating.
3.
A half-life is a constant for any radioactive isotope and is equal to the time required for half
the nuclei in a sample to decay. For example, carbon-14 has a half-life of 5730 years,
radon-222 has a half-life of 3.8 days and uranium-238 has a half-life of 4.5 billion years.
4.
If the half-life for an isotope is 35 days, how much of a 10g sample would remain after:
a. 35 days?
C 5g would remain
b. 70 days?
C 2.5g would remain
c. 105 days?
C 1.25g would remain
rate
5.
A decay curve is a curved line on a graph that shows the
decay.
at which radioactive isotopes
6.
Explain how you would determine how much of a 50g sample of iodine-131 would remain if
iodine-131 has a half-life of 8 days and 32 days have passed since the sample was made.
C If 32 days have passed and iodine-131 has a half-life of 8 days, then 2 half-lives
have passed. 32 × 0.5 × 0.5 = 8g.
C If the original sample was 50g: 50g × 0.5 × 0.5 = 12.5g would remain.
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7.
The isotope that undergoes radioactive decay is called the parent isotope
product of radioactive decay is called the daughter isotope .
8.
There are many common isotope pairs that exist. For example, the daughter isotope for carbon-14 is
nitrogen-14
and the parent isotope for lead-207 is uranium -235 .
9.
Explain how we can use potassium-40 and argon-40 as a clock.
and the stable
C Potassium-40 has a half-life of approximately 1.3 billion years and its daughter
isotope is argon-40. When rock is produced from lava there is no argon-40 gas (as
well as any other gases) present in the sample.
C As time passes some of the parent isotopes of potassium-40 are converted to their
corresponding daughter isotopes of argon-40 (and the argon is trapped in the rock
samples). Specifically, every 1.3 billion years half the potassium-40 isotopes are
converted to argon-40 isotopes.
C As the mass of the parent isotope drops, the mass of the daughter isotope
increases. We can use our knowledge of half-lives to determine how old a rock
sample is (in essence the isotopes are acting as a clock).
Chapter 7.3 - Nuclear Reactions
1. The two types of nuclear reactions include
fission
and
fusion
.
2.
Nuclear fission involves the splitting of a larger nucleus into two smaller nuclei, subatomic
particles and energy. The fission of a nucleus is accompanied by a very large release of
energy.
3.
Larger, heavier nuclei tend to be
nuclei split into lighter atoms.
4.
What are the downsides of performing fission reactions using nuclear reactors?
unstable
, and in order to increase stability atoms with heavy
C Nuclear reactors produce wastes that need to be safely stored for very long periods
of time.
C Nuclear reactors themselves also suffer significant deterioration.
C There is also concern that the nuclear material made be used in chemical warfare.
5.
A nuclear reaction is a process in which the nucleus of an atom changes. This change occurs when
the nucleus gains
or releases particles or energy. A small change in mass during
nuclear reactions results in a large change in energy
.
6.
Nuclear reactions are quite remarkable. A fission reaction involving just
one
gram of
uranium-235 releases the same amount of energy as burning two tonnes of coal!
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7.
Scientists have also developed methods in forcing nuclear reactions to occur. The term for this type
of nuclear reaction is an induced nuclear reaction
. During these forced reactions, a
nucleus is bombarded
with alpha particles, beta particles or gamma rays.
8.
Describe the process of the induced uranium-235 nuclear fission reaction that occurs in both
fission-style nuclear weapons and in Canadian nuclear power plants. Be sure to include the
production of the unstable uranium-236 isotope in your explanation, as well as all the reactants and
products of the reaction.
C During the nuclear fission reaction of uranium-235 a uranium-235 atom is bombarded
with a neutron.
C The nucleus of the uranium-235 absorbs the neutron, increasing the mass number by
one and creating the unstable uranium-236 isotope.
C The unstable uranium-236 isotope then undergoes a nuclear fission reaction.
C This reaction involves the splitting of the unstable uranium-236 into smaller nuclei,
neutrons and a lot of energy.
C Specifically, the reaction produces kypton-92, barium-141, 3 neutrons and energy.
9.
Why is the release of neutrons, kypton-92 and barium-141 in the induced uranium-235 reactions
important?
C The release of neutrons in the uranium-235 reaction is important because the
neutrons trigger more fission reactions to occur. Each reaction produces 3 neutrons
which can cause three additional fission reactions and start a large chain reaction of
fission reactions.
C Kypton-92 and barium-141 are unstable products. These products can further decay
into other isotopes releasing more useful energy.
10. The term used to describe the ongoing process in which one reaction initiates another or more
reactions is a chain reaction . These types of reactions can produce increasingly rapid
amounts of energy and may lead to violent
nuclear explosions.
11. Chain reactions can be controlled using
cadmium rods
to absorb neutrons.
12. Explain why chain reactions are a concern in nuclear power plants.
C Chain reactions can be controlled using materials that absorb neutrons. However, a
concern about nuclear power plants is that the nuclear reactions may race out of
control. So precise monitoring and adjusting must be done to ensure the nuclear
reactors remain under control and do not release harmful levels of radiation or
worse, cause an explosion.
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13. Explain what CANDU stands for, how it works and why it is a modern leader in the nuclear
technology of the world.
C CANDU stands for CANadian Deuterium Uranium reactor.
C The reactor is one of the safest nuclear reactors in the world and can be shut down
quickly if problems arise.
C CANDU reactors produce a lot of heat which is used to drive turbines that produce
electricity, further increasing the efficiency of the energy plant.
14. The fuel used in CANDU reactors comes in the form of
pellets. Once used, they are placed deep underground in
bundles of rods
containing uranium
stable
rock formations.
15. Nuclear fusion is the process in which two low mass nuclei join together to form a more
massive
nucleus. This type of reaction occurs on the sun
, as well as on other
stars
.
16. Fusion reactions require a tremendous amount of
occur.
temperature
and
pressure
to
17. Describe the fusion reaction that occurs in the Sun.
C At the core of the sun a deuterium and a tritium combine to form a helium atom a
neutron and a lot of energy.
1
1
C 1 H + 1 H ! 2 He + 1 n + energy
2
0
18. What do fission and fusion reactions have in common?
C Both fission and fusion reactions release large amounts of energy.
C They are also both used in nuclear weapons.
19. How do fission and fusion reactions differ? Be sure to consider the reactions, the products, and
human usage.
C Fission reactions involve a heavy unstable nucleus splitting apart to form 2 smaller
nuclei, while fusion reactions involve combining two lightweight nuclei to form a
heavier nucleus
C Fission reactions often produce daughter products that are also radioactive, while
fission reactions often do not produce radioactive products.
C Fission reactions are common in nuclear power plants, while fusion reactors have still
not be made (due to the high temperature and pressure required for the reactions,
and because the tremendous amount of heat produced is difficult to contain).
C Fusion reactions occur in nuclear weapons, but fission reactions must be conducted as
well to produce the temperature and pressure needed for the fusion reactions to
occur.
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Vocabulary to Know
Write a concise definition of each of these terms found in this chapter.
Alpha decayAlpha particle Beta decay Beta particle CANDU Chain reaction Daughter isotope Decay curve FissionFusionGamma decay Gamma particle Half-life Hazardous wastes Induced nuclear reaction Isotopes Light Mass number Nuclear equation Nuclear reaction Parent isotope Potassium-40 clock Radiation Radioactive decay Radiocarbon dating -
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