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P2 - Physics > Radioactivity > Flashcards

Radioactivity Flashcards

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0
Q

How does a radioactive substance become more stable?

A

It contains unstable nuclei that become more stable by emitting radiation

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1
Q

What is in every atom?

A

Protons & neutrons

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2
Q

What are the three main types of radiation?

A

Alpha
Beta
Gamma

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3
Q

How specific is radioactive decay?

A

Completely random, we can’t predict or influence when it will happen

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4
Q

Where does background radiation come from?

A

It comes from the environment, space or from devices such as X Ray machines

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5
Q

What is radon gas?

A

Product of the day of uranium found in certain areas

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6
Q

What is an isotopes

A

Element where the atoms have the same number of protons but different number of neutrons - same atomic number and different masses.

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7
Q

What did Rutherford do?

A

He carried out alpha radiation scattering experiments to prove that :

an atom has a small positively charged central nucleus where most of the atom is located

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8
Q

What is used to detect radioactivity?

A

A Geiger counter

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9
Q

Why was the plum pudding model rejected?

A

It couldn’t explain why some alpha particles were scattered through large angles

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10
Q

Why was the apparatus in a vacuum chamber?

A

To prevent air molecules from absorbing the alpha particulars

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11
Q

Why was the nuclear model excepted?

A

It could explain why the alpha particles are scattered and why some are scattered through large angles.

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12
Q

What is a radioactive substance?

A

A substance that gives out radiation from the nuclei of their atoms, no matter what is done to them

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13
Q

What is a beta particle?

A

A high speed electron with a negative charge

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14
Q

What is an alpha particle?

A

A helium nucleus
with 2 protons and 2 neutrons
Positive charge

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15
Q

What is alpha decay?

A

the nucleus
loses 2 protons and 2 neutrons
the mass number decreases by 4
atomic number increases by 2

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16
Q

What is beta decay?

A

In beta decay a neutron changed into a proton and an electron which is emitted

The mass number dosent change
The atomic number increases by 1

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17
Q

What is gamma radiation? & gamma decay?

A

Electromagnetic radiation and in gamma decay the nucleus loses energy

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18
Q

What is alpha radiation stopped by?

A

Paper

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19
Q

What is the range of alpha radiation?

A

A few cm

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20
Q

What is alpha radiation deflected by?

A

Magnetic fields

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21
Q

What stops beta radiation?

A

Thin metal

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22
Q

What is the range of beta radiation?

A

About a metre

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23
Q

What is beta radiation deflected by?

A

Electric and magnetic fields in the opposite direction to alpha radiation

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24
Q

What stops gamma radiation? & what is its range?

A

Thick lead

Unlimited range in air

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25
Q

What affect do magnetic and electric fields have on gamma radiation

A

No affect

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26
Q

What is the activity of a radioactive source?

A

The number of nuclei that decay per second

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27
Q

What is ionisation? & what affect does it have on a living fell?

A

The process by which atoms become charged because they lose electrons.

Ionisation in a living cell can damage or kill it.

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28
Q

What is the half life of a radioactive isotope?

A

The average time it takes for the number of unstable nuclei in the isotope to halve

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29
Q

What is count rate? What is it measured by?

A

The number of counts per second or minute and is measured using a Geiger counter

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30
Q

What 2 factors determine the purpose of a radioactive isotope?

A
  • half life

- type of radiation it emits

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31
Q

What emitters are used in smoke alarms?

A

Alpha emitters

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32
Q

How do smoke alarms use certain emitters?

A

They use alpha emitters because the alpha particles ionise the air in a gap in the circuit so the current an cross the gap.
If the smoke particles get in the way, the current across the gap drops and the alarm sounds

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33
Q

What emitters are used in automatic thickness monitoring? what factor should be considered with the isotope?

A
  • have a long half life

- beta emitter usually

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34
Q

what emitters are used for radioactive tracers?

A

Beta or gamma emitters that last long enough to monitor but not too long

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35
Q

What is nuclear fission?

A

The splitting of a nucleus into 2 approximately equal fragments
energy is realised
and then releasing 2 or 3 neutrons

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36
Q

What do you need for radioactive dating of a sample?

A

You need a radioactive isotope that

  • is present in the sample
  • has a half life about the same age as the sample

Eg.
uranium for igneous rocks
Carbon-14 for organic material

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37
Q

What is nuclear FUSION?

A

The process of

  • forcing 2 nuclei close enough together at high speed
  • SO they form a single larger nucleus
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38
Q

What is released when two light nuclei are fused together? What happens to do with the Suns core?

A

energy

nuclear fusion in the Suns core releases energy

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39
Q

What is an advantage of fusion l?

A
  • fuel is readily available because it’s in sea water

- the reaction product which is helium, is a non-radioactive gas

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40
Q

When does nuclear fission occur?

A
  • when a neutron
  • hits a uranium-235 nucleus or
  • plutonium-239 nucleus
  • the nucleus splits
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41
Q

What is a chain reaction?

A

A chain reaction occurs when each fission even cause further fission events

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42
Q

How is a chain reaction in a nuclear reactor controlled?

A
  • In a nucleus reactor control rods absorb neutrons
  • to ensure that on average only one neutron per fission
  • chain reactions slow down because there are fewer neutrons
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43
Q

Why is it difficult to make a nuclear fusion reactor?

A
  • The plasma needs to be at a very high temperature
  • before nuclear fusion can take place
  • this is to ensure that the nuclei have enough energy have enough energy to overcome the force of repulsion
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44
Q

Why is the plasma contained in a magnetic field?

A
  • the plasma is contained by a magnetic field so it DOSENT touch the reactor wall because if it did it would go cold and fusion would stop
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45
Q

What happens when two protons ( hydrogen nuclei) fuse?

A

They form a heavy hydrogen nucleus (deuterium)

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46
Q

What is radiation dose?

A

How much radiation each person gets in a year from a particular source

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47
Q

List sources of background radiation? & highlight the one that is man made?

A
  • cosmic rays
  • food & drink
  • medical
  • air travel
  • ground and buildings
  • natural radioactivity in the air
  • nuclear weapons testing
  • nuclear power
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48
Q

What does the effect on living cells or radiation of radioactive substances depend on?

A
  • the type and amount of radiation received
  • whether the source of the radiation is inside or outside the body
  • how long the living cells are exposed to the radiation
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49
Q

Where is alpha the most dangerous?

A

Inside rather than outside

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50
Q

Where must nuclear waste be stored? & what must be done first?

A
  • In safe and secure conditions for many years

- the unused uranium and plutonium should be removed from it

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51
Q

How can alpha beta and gamma radiation be separated?

A

A magnetic or electric field can be used

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52
Q

Why is alpha beta and gamma radiation dangerous?

A

They ionise substances they pass through - this can damage or kill the cell

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53
Q

What type of radiation is

A uncharged
B charged
C negatively charged

A

A gamma rays
B alpha
C BETA

54
Q

What is beta radiation

A

Beta particles that are high energy elections created in and emitted from unstable nuclei

55
Q

What makes gamma decay different from alpha and beta decay?

A

Gamma decay is an electromagnetic wave whilst in alpha and beta decay a charged particle is emitted from the nucleus

56
Q

What type of particles do neutron-heavy nuclei emit? & neutron-light nuclei emit?

A

Heavy - Negative beta particles

Light - Positive beta particles

57
Q

What do the heaviest elements emit?

A

Alpha particles

58
Q

What does any sufficiently energetic nuclei emit?

A

Gamma rays

59
Q

What is gamma particles charge and why?

A

They have no charge because they are electromagnetic waves

60
Q

How heavy are alpha beta and gamma rays?

A

alpha - very heavy
Beta - x7300 lighter than alpha
Gamma - no mass

61
Q

What is radon gas?

A

Gas created by the radioactive decay of uranium in the earths crust

62
Q

One other substance that can be used as fuel in a nuclear reactor?

A

plutonium (239)

63
Q

Describe how the energy from nuclear fuels generates electricity?

A

1 energy used to heat water
2 produces high pressure steam
3 the steam drives a turbine
4 which then turns a generator

64
Q

What factors could lead to a greater risk of radioactive poisoning?

A
  • working in a nuclear power station
  • having more x rays than normal
  • living in a place of high radon concentration eg Cornwall
  • living at altitude
65
Q

What does the plum pudding model represent?

A

The positively charged matter in the atom evenly spread about (as in a pudding)

Electrons buried inside (like plums within it)

66
Q

What does fission mean?

A

To split

67
Q

What do control rods do?

A

’ soak up ‘ excess neutrons

68
Q

Why does fusion only occur at very high temperatures and pressures?

A

They have to be pushed together with a force large enough to overcome the force of repulsion

69
Q

Which two types of radiation will pass through a sheet of card?

A

Beta

Gamma

70
Q

Which two types of radiation would be deflected by an electric field?

A

Alpha

Beta

71
Q

Which type of radiation has the greatest range in air?

A

Gamma radiation

72
Q

What did scientists think the pudding part of an atom was?

A

Positively charged matter that was evenly spaced out

73
Q

Where does most of the helium gas on earth come from?

A

Alpha decay of radioactive elements of rocks in the earths crust

74
Q

Do gamma particles have charge?

A

No mass

75
Q

What is the difference between alpha&beta decay and gamma decay?

A

In gamma decay an electromagnetic wave is emitted instead of a charged particle

76
Q

How did Rutherford prove the nucleus?

A

From the measurements from alpha scattering experiment

77
Q

Why did Rutherford experiment take place in a vacuum?

A

To prevent air molecules from absorbing alpha particles I

78
Q

How did Rutherford prove the nucleus?

A

From the measurements from alpha scattering experiment

79
Q

Why did Rutherford experiment take place in a vacuum?

A

To prevent air molecules from absorbing alpha particles I

80
Q

What happens in gamma decay?

A

The nucleus loses energy

81
Q

How can you separate radiations of alpha and beta?

A

Using a magnetic field or an electric field

82
Q

What happens when gamma radiation comes in to contact with a field?

A

It’s unaffected

83
Q

What direction is beta deflected by an electric or magnetic field?

A

In the opposite direction to alpha

84
Q

What is ionisation?

A

The process by which atoms become charged because they lose electrons

85
Q

What is the activity of a radioactive source?

A

Number of nuclei that decay per second

86
Q

How does an alarm work?

A

An alpha particle ionises he air in a gap in the circuit so the current can cross the gap

If smoke particles get in the way the current across the gap drops and the alarm sounds

87
Q

What type of radiation is used for radioactive tracing and why?

A

Beta or gamma because they last long enough to monitor

88
Q

When does a fission occur?

A

When fissions cause further fission events

89
Q

What do control rods do in a nuclear reactor?

A

They absorb surplus fission neutrons to ensure that only one neutron goes onto produce further fission

90
Q

Why is the reactor core made of steel?

A

Thick steal to withstand high temperature and pressure

91
Q

Why is water used in a pressurised water reactor?

A

The water acts as a moderator

I slow down the fission neutrons

92
Q

What is waters alternate use in a PWR?

A

Acts as a coolant
It’s molecules gain kinetic energy from the neutrons and fuel rods
It gives up energy via a heat exchanger

93
Q

Sources of background radiation?

A 
Food 
Drink
Cosmic rays
Medical
Air travel
Nuclear power /weapons
94
Q

What radioactive isotope emits naturally through the ground?

A

Radom gas - alpha

95
Q

Why is a very high temperature used in a fusion reactor?

A

To ensure the nuclei have enough energy to overcome the force of repulsion

96
Q

How is the plasma heated in fusion?

A

A very large electric current

97
Q

What colour is a proton?

A

Black

98
Q

What colour is a neutron?

A

White

99
Q

What does nuclear fission release?

A

Energy (electromagnetic radiation as gamma rays)

2 or 3 neutrons at high speed
2 aprox equal fragments of nucleus
These release kinetic energy

100
Q

What causes further fission?

A

Fission neutrons may cause further fission resulting in a chain reaction

101
Q

Why is one fission neutron (aprox) released from each fission of two or three?

A

To ensure energy is released at a steady rate

102
Q

What causes further fission?

A

Fission neutrons may cause further fission resulting in a chain reaction

103
Q

Why is one fission neutron (aprox) released from each fission of two or three?

A

To ensure energy is released at a steady rate

104
Q

How does the energy of fission provide energy?

A

Energy used to heat water
Produces high pressure steam
Steam drives turbine
Which turns a generator

105
Q

How is fission energy made useful?

A

Energy used to heat water
Produced high pressure steam
Steam drives turbine
Turbine turns a generator

106
Q

What does water do in a nuclear reactor?

A

Coolant

Moderator - slows the fission neutrons as they collide with water molecules
Chain reaction stops

107
Q

What is in a nuclear reactor?

A

Control rods
Fuel rods
High pressure water

108
Q

Describe the reactor core in a nuclear reactor?

A

Thick steel to withstand high temp and pressure

Thick concrete walls to absorb radiation that escaped from steel

109
Q

What do the control rods do in a nuclear reactor?

A

Absorb surplus neutrons
Keeps chain reaction Under control

The lower the rods the fewer neutrons chain reaction slows down stops

110
Q

When does fission happen?

A

Occurs when a slow moving neutron hits the nucleus of uranium -235 or plutonium -239

And the nucleus splits
And two or three neutrons released

111
Q

How does fission release energy?

A

Radiation energy

Kinetic energy from the 2/3 neutrons released and fragmented nuclei

112
Q

What is the problem with fusion reactors?

A

Very high temperature needed before the plasma of light nuclei fuse

because two nuclei will repeal as they have the same positive charge

113
Q

Why is a magnetic field needed in a fission reactor?

A

So it dosent touch the reactor walls

If it did it would go cold and the fission would stop

114
Q

Fusion in the sun?

A

Two protons of hydrogen fuse to form heavy hydrogen ( 2-1)
Two heavy hydrogen nuclei collide to form 4-2 (helium)

Energy released at each stage is carried as kinetic energy

115
Q

What is an ion?

A

An atom that had lost or gained electrons

116
Q

Why is it important that the doctor used an isotope with a short half life rather than a long half life?

A

Short half life the level of radiation in the body decreases rapidly
To a safe level

117
Q

Why do towns need to stay connected to national grid even with own electricity supply?

A

Electricity demand may be greater than supply

No case it fails

118
Q

In the nuclear model, what is most of the atom?

A

Empty space

119
Q

Natural sources of radiation?

A

Rocks

Cosmic rays from so we

120
Q

Artificial sources of radiation?

A

Fallout from nuclear weapons tests

Nuclear accidents

121
Q

Definition of radioactive substance?

A

Some substances give out radiation from the nuclei or their atoms all the time

122
Q

Describe the basic structure of an atom?

A

A small centeral nucleus composed of protons and neutrons

Surrounded by electrons

123
Q

Describe the difference in alpha and beta particles when deflected?

A

Alpha deflected LESS

And in the opposite direction to Beta

124
Q

What do most nuclear reactors use?

A

Uranium 235

125
Q

What has to first happen for fission to offer?

A

Uranium or plutonium nucleus must first absorb a neutron

126
Q

What happens to a nucleus undergoing fission?

A

The nucleus splits into two smaller nuclei and two or three neutrons and energy is released

127
Q

How do planets form?

A

Smaller masses may also form and be attracted to a larger made to become planets

128
Q

Why was Rutherford nuclear model quickly accepted?

A

It agreed with the measurements made in experiments
It predicted the existence of the neutron
It explains radioactivity in terms of changes that happen to an unstable nucleus

129
Q

Describe the plum pudding model?

A

Positively charged matter evenly spread out and electrons buried inside

130
Q

What happens during nuclear fission

A

NUCLEI split

131
Q

Where are isotopes produced in a nuclear power station?

A

NUCLEAR REACTOR

132
Q

How does water act as a coolant?

A

Molecules gain kinetic energy from the neutrons and the fuel rods
Water pumped into core
Then it goes into sealed pipes to and from s heatb exchanger

P2 - Physics (5 decks)

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