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Radioactivity Flashcards

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AP® Physics flashcards Physics 101 flashcards
1
Q

What is the difference between an atom and a molecule?

A

A molecule is two or more atoms bonded together.

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2
Q

What is an element?

A

Substance where all atoms have the same atomic number / number of protons.

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3
Q

What do the part in the middle of an atom called?

A

Nucleus

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4
Q

Name two subatomic particles.

A

Proton / Neutron / Electron

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5
Q

What are the negatively charged particles in an atom called?

A

Electrons

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6
Q

What are the positively charged particles in an atom called?

A

Protons

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7
Q

Where is most of the mass of an atom concentrated?

A

The nucleus

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8
Q

Which subatomic particles have a negligible mass?

A

Electrons

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9
Q

How did scientists discover that atoms have tiny nuclei?

A

Fires particles at atom / gold sheet

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10
Q

Who investigated atoms by firing particles at atoms / a gold sheet?

A

Rutherford

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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

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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

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13
Q

What charge do electrons have?

A

negative / -1

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14
Q

How much mass do electrons have?

A

Negligible / hardly any

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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

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16
Q

Rutherford investigated the structure of the atom. What did he do?

A

He fired alpha particles at gold foil

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17
Q

What happened to most of the alpha particles during Rutherford’s experiment?

A

Went straight through

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18
Q

Why did Rutherford conclude that most of the mass was in the centre of the atom?

A

A few particles bounced back

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19
Q

What is the relative mass of a proton?

A

1

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20
Q

What are isotopes?

A

Atoms of the same element with different masses

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21
Q

Which subatomic particle has no charge?

A

Neutron

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22
Q

What is another name for nucleon number?

A

Mass number

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23
Q

What is the mass number of an atom?

A

Total number of nutreons and protons

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24
Q

What is the atomic number of an atom?

A

Number of protons

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25
Q

What is another name for atomic number?

A

Proton number

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26
Q

What is the relative mass of a neutron?

A

1

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27
Q

What is the relative charge of a proton?

A

+1

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28
Q

What is different between two isotopes of the same element?

A

Number of neutrons in the atomic nucleus

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29
Q

How are electrons arranged in an atom?

A

Shells / Orbits / Energy levels

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30
Q

What is ionisation?

A

When an atom gains or loses an electron

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31
Q

What charge does an ion have when it had lost an electron?

A

Positive

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32
Q

Name one source of background radiation in everyday life.

A

Space, Food, Rocks, etc.

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33
Q

Name one thing that can detect radiation.

A

Geiger-Müller tube / photographic film

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34
Q

What is ionising radiation?

A

Radiation that can cause atoms to form ions

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35
Q

Is most background radiation natural or from human causes?

A

Natural

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36
Q

What does radon gas come from?

A

Uranium in some rocks

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37
Q

What are cosmic rays?

A

Charged particles from stars

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38
Q

Why is background radiation different in different places?

A

Different rocks and / or building materials

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39
Q

What happens to photographic film when radiation hits it?

A

Darkens

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40
Q

What is the name of a common instrument that detects radiation?

A

Geiger-Müller tube

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41
Q

What is a count rate?

A

The number of clicks / The number of radiation events detected per second

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42
Q

Name two types of ionising radiation that consists of particles.

A

Alpha, Beta, Positron

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43
Q

Which high-frequency electromagnetic waves can be produced by radioactive decay?

A

Gamma rays

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44
Q

What is an alpha particle?

A

Helium nucleus / 2 protons, 2 neutrons

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45
Q

What is a beta particle?

A

Electron ejected from the nucleus of an atom / high-speed electron

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46
Q

What is the relative mass of an alpha particle?

A

4

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47
Q

What is the relative charge of an alpha particle?

A

+2

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48
Q

What is the relative charge on a beta particle?

A

1

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49
Q

What is the relative charge of a positron?

A

+1

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50
Q

Which form of radiation is the most penetrating?

A

Gamma rays

51
Q

Which form of radiation is the most ionising?

A

Alpha particles

52
Q

What happens to the nucleus of an atom when it emits an alpha particle?

A

Becomes more stable / changes to a different element

53
Q

What happens to the nucleus of an atom if it ejects a neutron?

A

Changes to a different isotope of the same element

54
Q

What happens to the atomic number of a nucleus when an alpha particle is emitted?

A

It goes down by 2

55
Q

What happens to the mass number of a nucleus when an alpha particle is emitted?

A

It goes down by 4

56
Q

How is a beta particle formed?

A

A neutron changes into a proton and an electron

57
Q

What happens to the attomic number of a nucleus when a beta particle is emitted?

A

It goes up by 1

58
Q

How is a positron formed?

A

A proton changes into a neutron and a positron

59
Q

What happens to the atomic number of a nucleus when a positron is emitted?

A

It goes down by 1

60
Q

What is the symbol for an alpha particle?

A

42He / a

61
Q

What is the symbol for a beta particle?

A

β^- / -10e

62
Q

What does the ‘activity’ of a radioactive source mean?

A

The number of decays per second

63
Q

What does half-life mean?

A

The time it takes for the activity to halve / the number of unstable nuclei to halve

64
Q

What is the unit for measuring the activity of a source?

A

becquerel (bq)

65
Q

What does one becquerel represent?

A

1 decay per second

66
Q

Why can we not predict exactly how many nuclei will decay each second?

A

Decay is a random process

67
Q

How does the activity of a radioactive source change over time?

A

It gets less

68
Q

Why does the activity of a source get less over time?

A

After each decay, there are fewer unstable nuclei left to decay

69
Q

What does the half-life tell you about the activity of a sample of radioactive material?

A

the time until the activity falls by half

70
Q

What does the half-life tell you about the number of unstable nuclei in a sample of radioactive material?

A

the time until the number of unstable nuclei falls by half

71
Q

Name one disease that can be caused by radiation.

A

Cancer

72
Q

Name one type of job that may involve being exposed to nuclear radiation

A

hospital worker/nurse/doctor or scientist or nuclear power station worker

73
Q

What has happened if you are contaminated by radioactive material?

A

You have got it on your skin or inside your body.

74
Q

Which form of radiation is used to kill microorganisms?

A

gamma

75
Q

Name two things that are irradiated to kill microorganisms in or on them.

A

irradiating fruit, sterilising surgical instruments

76
Q

Why are sources of gamma radiation used as tracers?

A

Gamma rays can pass through other materials easily.

77
Q

Describe one use of a tracer.

A

finding leaks in water pipes, or diagnosing medical problems

78
Q

Which form of radiation is used to control the thickness of manufactured materials?

A

beta

79
Q

Which property of beta radiation is important for this use?

A

medium penetration

80
Q

What happens to the amount of radiation passing through the material if the material is thicker than normal?

A

it reduces

81
Q

What happens to the pressure on the rollers if the material becomes too thick?

A

increase pressure on rollers

82
Q

What harm can radiation do to the human body?

A

cause burns/cancer

83
Q

Describe one safety precaution when using radioactive sources.

A

any sensible precaution, such as wearing protective clothing, keeping away from it, using as little radiation as possible

84
Q

What can being exposed to radiation do to your skin?

A

burn

85
Q

What is the name for damage done to the instructions contained within the DNA of a cell?

A

mutation

86
Q

Why are radioactive sources handled with tongs?

A

to keep the person further from the source

87
Q

Why are radioactive sources stored in lead-lined boxes?

A

to stop all alpha and beta radiation, and limit gamma radiation

88
Q

A doctor supervises a patient being treated with radioactivity from a different room. Why?

A

to keep the doctor away from the radiation

89
Q

Someone is exposed to radiation by breathing in some radioactive gas. Has the person been irradiated or contaminated?

A

contaminated

90
Q

What does irradiation mean?

A

being exposed to radiation from an external source

91
Q

Why do workers cleaning up after a nuclear accident wear overalls and breathing masks?

A

to prevent them becoming contaminated

92
Q

What is a tracer?

A

a substance that emits gamma rays that can be put into a person to diagnose problems/find water leaks

93
Q

Name one health problem that can be treated with radiation from a radioactive source.

A

cancer

94
Q

What type of radiation do tracers usually emit?

A

gamma

95
Q

How is the location of a tracer inside the body detected?

A

gamma camera/PET scanner

96
Q

How can a tracer be put into the body?

A

injected/swallowed/inhaled

97
Q

State two medical problems that can be detected using tracers.

A

internal bleeding, cancers

98
Q

What type of radiation is emitted by tracers used in PET scanners?

A

positron

99
Q

How does a PET scanner locate a tumour?

A

from gamma rays produced when a positron meets an electron

100
Q

What is external radiotherapy?

A

radiation sent into a patient from outside

101
Q

What is internal radiotherapy?

A

when a radioactive source is put inside the patient

102
Q

What is the process that releases energy in the Sun?

A

nuclear fusion

103
Q

What is the process that releases energy in nuclear power stations?

A

nucleur fission

104
Q

In which type of nuclear reaction do small nuclei join up to make large ones?

A

nucleur fusion

105
Q

In which type of nuclear reaction do unstable nuclei randomly emit small particles or gamma radiation?

A

nuclear decay/radioactive decay

106
Q

What happens in a fission reaction?

A

A large nucleus breaks up to form smaller nuclei.

107
Q

What is the fuel used in nuclear power stations?

A

uranium-235

108
Q

What do fossil fuel power stations emit that nuclear power stations do not?

A

carbon dioxide

109
Q

What problem is carbon dioxide contributing to?

A

climate change, increasing the greenhouse effect, global warming

110
Q

Why is an accident in a nuclear power station likely to be more harmful than one in a fossil fuel power station?

A

Radioactive material can spread a long way and is more dangerous than the products of an accident in a fossil fuel power station.

111
Q

Why do many people oppose nuclear power?

A

They do not think it is safe.

112
Q

What is a chain reaction?

A

where one reaction causes another, and that causes another reaction, and so on

113
Q

What are inserted into the core of a nuclear reactor to slow it down?

A

control rods

114
Q

What needs to be absorbed by a uranium-235 nucleus to make it split up?

A

neutron

115
Q

What are daughter nuclei?

A

the nuclei formed when a large nucleus splits up

116
Q

How is uranium-235 put into a reactor?

A

in fuel rods

117
Q

What is a moderator?

A

a substance that slows down the neutrons produced by fission reactions

118
Q

Why is a moderator needed?

A

to increase the chance of the neutrons being absorbed by other uranium-235 nuclei

119
Q

What happens to neutrons that hit a control rod?

A

they are absorbed

120
Q

What is the series of fission reactions in a reactor called?

A

chain reaction

121
Q

How is energy from fission reactions used to generate electricity?

A

turns water to steam, which spins a turbine, which drives a generator

122
Q

What force makes it difficult to force two hydrogen nuclei together?

A

electrostatic repulsion

123
Q

Why do we not use fusion to generate electricity?

A

technology not developed/too difficult to produce high temperatures and pressure

Physics (6 decks)

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