Radioactivity Flashcards
(123 cards)
1
Q
What is the difference between an atom and a molecule?
A
A molecule is two or more atoms bonded together.
2
Q
What is an element?
A
Substance where all atoms have the same atomic number / number of protons.
3
Q
What do the part in the middle of an atom called?
A
Nucleus
4
Q
Name two subatomic particles.
A
Proton / Neutron / Electron
5
Q
What are the negatively charged particles in an atom called?
A
Electrons
6
Q
What are the positively charged particles in an atom called?
A
Protons
7
Q
Where is most of the mass of an atom concentrated?
A
The nucleus
8
Q
Which subatomic particles have a negligible mass?
A
Electrons
9
Q
How did scientists discover that atoms have tiny nuclei?
A
Fires particles at atom / gold sheet
10
Q
Who investigated atoms by firing particles at atoms / a gold sheet?
A
Rutherford
11
Q
What is the name of the model that helps to explain the properties of materials?
A
Kinetic theory / particle or model theory / model
12
Q
Which of the following is approximately the diameter of an atom - a hundredth of a millimetre, a thousandth of a millimetre or a millionth of a millimetre
A
A millionth of a millimetre
13
Q
What charge do electrons have?
A
negative / -1
14
Q
How much mass do electrons have?
A
Negligible / hardly any
15
Q
In Thompson’s model, the atom was positively charged with tiny negative charges in it. What is this model called.
A
Plum pudding model
16
Q
Rutherford investigated the structure of the atom. What did he do?
A
He fired alpha particles at gold foil
17
Q
What happened to most of the alpha particles during Rutherford’s experiment?
A
Went straight through
18
Q
Why did Rutherford conclude that most of the mass was in the centre of the atom?
A
A few particles bounced back
19
Q
What is the relative mass of a proton?
A
1
20
Q
What are isotopes?
A
Atoms of the same element with different masses
21
Q
Which subatomic particle has no charge?
A
Neutron
22
Q
What is another name for nucleon number?
A
Mass number
23
Q
What is the mass number of an atom?
A
Total number of nutreons and protons
24
Q
What is the atomic number of an atom?
A
Number of protons
25
What is another name for atomic number?
Proton number
26
What is the relative mass of a neutron?
1
27
What is the relative charge of a proton?
+1
28
What is different between two isotopes of the same element?
Number of neutrons in the atomic nucleus
29
How are electrons arranged in an atom?
Shells / Orbits / Energy levels
30
What is ionisation?
When an atom gains or loses an electron
31
What charge does an ion have when it had lost an electron?
Positive
32
Name one source of background radiation in everyday life.
Space, Food, Rocks, etc.
33
Name one thing that can detect radiation.
Geiger-Müller tube / photographic film
34
What is ionising radiation?
Radiation that can cause atoms to form ions
35
Is most background radiation natural or from human causes?
Natural
36
What does radon gas come from?
Uranium in some rocks
37
What are cosmic rays?
Charged particles from stars
38
Why is background radiation different in different places?
Different rocks and / or building materials
39
What happens to photographic film when radiation hits it?
Darkens
40
What is the name of a common instrument that detects radiation?
Geiger-Müller tube
41
What is a count rate?
The number of clicks / The number of radiation events detected per second
42
Name two types of ionising radiation that consists of particles.
Alpha, Beta, Positron
43
Which high-frequency electromagnetic waves can be produced by radioactive decay?
Gamma rays
44
What is an alpha particle?
Helium nucleus / 2 protons, 2 neutrons
45
What is a beta particle?
Electron ejected from the nucleus of an atom / high-speed electron
46
What is the relative mass of an alpha particle?
4
47
What is the relative charge of an alpha particle?
+2
48
What is the relative charge on a beta particle?
1
49
What is the relative charge of a positron?
+1
50
Which form of radiation is the most penetrating?
Gamma rays
51
Which form of radiation is the most ionising?
Alpha particles
52
What happens to the nucleus of an atom when it emits an alpha particle?
Becomes more stable / changes to a different element
53
What happens to the nucleus of an atom if it ejects a neutron?
Changes to a different isotope of the same element
54
What happens to the atomic number of a nucleus when an alpha particle is emitted?
It goes down by 2
55
What happens to the mass number of a nucleus when an alpha particle is emitted?
It goes down by 4
56
How is a beta particle formed?
A neutron changes into a proton and an electron
57
What happens to the attomic number of a nucleus when a beta particle is emitted?
It goes up by 1
58
How is a positron formed?
A proton changes into a neutron and a positron
59
What happens to the atomic number of a nucleus when a positron is emitted?
It goes down by 1
60
What is the symbol for an alpha particle?
42He / a
61
What is the symbol for a beta particle?
β^- / -10e
62
What does the ‘activity’ of a radioactive source mean?
The number of decays per second
63
What does half-life mean?
The time it takes for the activity to halve / the number of unstable nuclei to halve
64
What is the unit for measuring the activity of a source?
becquerel (bq)
65
What does one becquerel represent?
1 decay per second
66
Why can we not predict exactly how many nuclei will decay each second?
Decay is a random process
67
How does the activity of a radioactive source change over time?
It gets less
68
Why does the activity of a source get less over time?
After each decay, there are fewer unstable nuclei left to decay
69
What does the half-life tell you about the activity of a sample of radioactive material?
the time until the activity falls by half
70
What does the half-life tell you about the number of unstable nuclei in a sample of radioactive material?
the time until the number of unstable nuclei falls by half
71
Name one disease that can be caused by radiation.
Cancer
72
Name one type of job that may involve being exposed to nuclear radiation
hospital worker/nurse/doctor or scientist or nuclear power station worker
73
What has happened if you are contaminated by radioactive material?
You have got it on your skin or inside your body.
74
Which form of radiation is used to kill microorganisms?
gamma
75
Name two things that are irradiated to kill microorganisms in or on them.
irradiating fruit, sterilising surgical instruments
76
Why are sources of gamma radiation used as tracers?
Gamma rays can pass through other materials easily.
77
Describe one use of a tracer.
finding leaks in water pipes, or diagnosing medical problems
78
Which form of radiation is used to control the thickness of manufactured materials?
beta
79
Which property of beta radiation is important for this use?
medium penetration
80
What happens to the amount of radiation passing through the material if the material is thicker than normal?
it reduces
81
What happens to the pressure on the rollers if the material becomes too thick?
increase pressure on rollers
82
What harm can radiation do to the human body?
cause burns/cancer
83
Describe one safety precaution when using radioactive sources.
any sensible precaution, such as wearing protective clothing, keeping away from it, using as little radiation as possible
84
What can being exposed to radiation do to your skin?
burn
85
What is the name for damage done to the instructions contained within the DNA of a cell?
mutation
86
Why are radioactive sources handled with tongs?
to keep the person further from the source
87
Why are radioactive sources stored in lead-lined boxes?
to stop all alpha and beta radiation, and limit gamma radiation
88
A doctor supervises a patient being treated with radioactivity from a different room. Why?
to keep the doctor away from the radiation
89
Someone is exposed to radiation by breathing in some radioactive gas. Has the person been irradiated or contaminated?
contaminated
90
What does irradiation mean?
being exposed to radiation from an external source
91
Why do workers cleaning up after a nuclear accident wear overalls and breathing masks?
to prevent them becoming contaminated
92
What is a tracer?
a substance that emits gamma rays that can be put into a person to diagnose problems/find water leaks
93
Name one health problem that can be treated with radiation from a radioactive source.
cancer
94
What type of radiation do tracers usually emit?
gamma
95
How is the location of a tracer inside the body detected?
gamma camera/PET scanner
96
How can a tracer be put into the body?
injected/swallowed/inhaled
97
State two medical problems that can be detected using tracers.
internal bleeding, cancers
98
What type of radiation is emitted by tracers used in PET scanners?
positron
99
How does a PET scanner locate a tumour?
from gamma rays produced when a positron meets an electron
100
What is external radiotherapy?
radiation sent into a patient from outside
101
What is internal radiotherapy?
when a radioactive source is put inside the patient
102
What is the process that releases energy in the Sun?
nuclear fusion
103
What is the process that releases energy in nuclear power stations?
nucleur fission
104
In which type of nuclear reaction do small nuclei join up to make large ones?
nucleur fusion
105
In which type of nuclear reaction do unstable nuclei randomly emit small particles or gamma radiation?
nuclear decay/radioactive decay
106
What happens in a fission reaction?
A large nucleus breaks up to form smaller nuclei.
107
What is the fuel used in nuclear power stations?
uranium-235
108
What do fossil fuel power stations emit that nuclear power stations do not?
carbon dioxide
109
What problem is carbon dioxide contributing to?
climate change, increasing the greenhouse effect, global warming
110
Why is an accident in a nuclear power station likely to be more harmful than one in a fossil fuel power station?
Radioactive material can spread a long way and is more dangerous than the products of an accident in a fossil fuel power station.
111
Why do many people oppose nuclear power?
They do not think it is safe.
112
What is a chain reaction?
where one reaction causes another, and that causes another reaction, and so on
113
What are inserted into the core of a nuclear reactor to slow it down?
control rods
114
What needs to be absorbed by a uranium-235 nucleus to make it split up?
neutron
115
What are daughter nuclei?
the nuclei formed when a large nucleus splits up
116
How is uranium-235 put into a reactor?
in fuel rods
117
What is a moderator?
a substance that slows down the neutrons produced by fission reactions
118
Why is a moderator needed?
to increase the chance of the neutrons being absorbed by other uranium-235 nuclei
119
What happens to neutrons that hit a control rod?
they are absorbed
120
What is the series of fission reactions in a reactor called?
chain reaction
121
How is energy from fission reactions used to generate electricity?
turns water to steam, which spins a turbine, which drives a generator
122
What force makes it difficult to force two hydrogen nuclei together?
electrostatic repulsion
123
Why do we not use fusion to generate electricity?
technology not developed/too difficult to produce high temperatures and pressure
