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GCSE Physics ⚛️ > Topic 6 ☢️☄️ > Flashcards

Topic 6 ☢️☄️ Flashcards

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1
Q

What is the overall charge of an atom?

A

Neutral

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2
Q

What is the overall charge of a nucleus of an atom?

A

Positive

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3
Q

What is the relative mass of a proton?

A

1

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4
Q

What is the relative charge of a proton?

A

+1

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5
Q

What is the relative mass of a neutron?

A

1

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6
Q

What is the relative charge of a neutron?

A

0

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7
Q

What is the relative mass of an electron?

A

0.0005 or 1/1850

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8
Q

What is the relative charge of an electron?

A

-1

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9
Q

What is an isotope?

A

Atoms with the same number of protons but different numbers of neutrons.

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10
Q

What can alpha radiation be used for?

A

CT scans and Radiotherapy

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11
Q

What are alpha particles made of?

A

2 neutrons and 2 protons (same as a helium nucleus)

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12
Q

What are alpha particles used for?

A

Smoke alarms

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13
Q

How does a smoke alarm work regarding alpha particles?

A
  • Radioactive substance emits alpha radiation
  • Alpha particles ionise the air in the detector and cause a current to flow between
  • Smoke interferes with radiation so the air is no longer ionised and no current can flow
  • Thus reduction in current flow triggers the alarm
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14
Q

Are Beta particles ionising?

A

Highly ionising

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15
Q

When are Beta particles emitted?

A

Emitted when a neutron turns into a proton in the nucleus.

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16
Q

What can Beta particles be used for?

A

Thickness detectors

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17
Q

How do thickness detectors work? And what type of radiation is involved?

A
  • Beta particles passed through paper.
  • Machine stopped if paper is too thick.
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18
Q

What is nuclear fission?

A

Splitting of a large and unstable nuclei.

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19
Q

How many and what particles are released during nuclear fission?

A

Two or three neutrons

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20
Q

Unstable nuclei must absorb what?

A

A slow-moving neutron

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21
Q

Where are uncontrolled chain reactions used?

A

Nuclear weapons

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22
Q

What does nuclear fission produce?

A

Two smaller nuclei and releases energy.

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23
Q

What is nuclear fusion?

A

Joining of two light nuclei into a larger nucleus.

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24
Q

What atmosphere does nuclear fusion require?

A

Very high temperatures and pressures

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25
Q

In B- (Beta minus) decay what is released?

A

Neutron turns into a proton and an electron is released.

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26
Q

In B- (Beta minus) decay what changes in the decay equation? Hint: atomic mass/number.

A

Atomic (Proton) number increases
Mass number stays constant

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27
Q

What happens and is released in B+ (positron) decay?

A

Proton turns into a neutron and releases a positron.

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28
Q

I’m B+ (positron) decay what changes in the decay equation? Hint: atomic mass/number

A

Atomic (proton) number decreases
Mass sumner stays constant

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29
Q

What is count rate measured with in nuclear decay?

A

A Geiger-Muller tube/meter

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30
Q

What is nuclear decay measured in?

A

Becquerels (Bq)

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31
Q

Nuclear decay is RANDOM. What does this mean?

A

Which nuclei and when it will decay is unpredictable.

32
Q

Give an approximation for the radius of an atom?

A

1x10 to the -10 metres

33
Q

Approximately what proportion of the total radius of an atom is the radius of the nucleus?

A

1 / 10,000

34
Q

Give two ways that an atom’s electron arrangement can be changed.

A
  1. Absorbing electromagnetic radiation
  2. Emitting electromagnetic radiation
35
Q

Explain how an atom’s electron arrangement changes when it absorbs EM radiation.

A
  • Electrons move to higher energy levels
  • They move away from the nucleus
36
Q

Explain how an atom’s electron arrangement changes when it emits EM radiation.

A
  • Electrons move to a lower energy level
  • They move towards the nucleus
37
Q

What is the name given to the number of protons in an atom?

A

Atomic number

38
Q

What is an atom’s mass number?

A

The total number of protons and neutrons in the atom.

39
Q

How do atoms turn into positive ions?

A
  • They lose one or more of their outer electrons
  • Electrons are negative,y charged, so the resultant charge of the atom is positive
40
Q

State the four types of nuclear radiation.

A
  1. Alpha particles
  2. Beta particles
  3. Positrons
  4. Gamma rays
41
Q

What is meant by background radiation?

A
  • Radiation that is always present
  • It is in very small amounts and so is not harmful
42
Q

Give 4 sources of background radiation.

A
  1. Rocks
  2. Cosmic rays from space
  3. Nuclear weapon testing
  4. Nuclear accidents
43
Q

What is the range of an alpha particle through air?

A

A few centimetres (2-10cm)

44
Q

What will block beta radiation?

A

A thin sheet of aluminium

45
Q

What will block gamma radiation?

A

Several centimetres of lead
A few metres of concrete

46
Q

Which type of radiation is most ionising?

A

Alpha radiation

47
Q

Which type of radiation is least ionising?

A

Gamma radiation

48
Q

How does gamma émission affect mass/charge of an atom?

A

Both mass and charge remain unchanged

49
Q

Describe the plum-pudding model of the atom.

A

A sphere of positive charge, with the negatively charged electrons distributed evenly through it.

50
Q

Prior to the discovery of the electron what was believed about the atom?

A

The atom was believed to be indivisible

51
Q

What name is given to the currently accepted model of the atom?

A

The Bohr model.

52
Q

Describe Rutherford’s experiment?

A
  • Alpha particles (charge +2) were fired at a think sheet of gold foil
  • Most particles went straight through
  • Some particles were deflected by small angles (<90°)
  • Some particles were deflected by large angles (>90°)
53
Q

What are the conclusions of Rutherford’s experiment?

A
  • Most of the atom is empty space
    -The nucleus has a positive charge
  • Most of the mass is concentrated in the nucleus
54
Q

What is the process called when a neutron changes into a proton and an electron?

A

Beta minus decay

55
Q

When alpha decay occurs, what happens to the atomic number and the mass number of the atom?

A
  • Atomic number decreases by 2
  • Mass number decreases by 4
  • A new element is made since the atomic number has changed
56
Q

What effect does beta minus decay have on the mass number an atomic number of an atom?

A
  • The mass number stays the same as the total number of neutrons and protons hasn’t changed
  • The atomic number increases since there is one more proton
57
Q

Define the half-life of a radioactive isotope.

A
  • The time it takes for the number of unstable nuclei in a substance to halve.
  • The time it takes for the count rate from a sample to fall to half its initial level.
58
Q

Give example uses of radioactivity.

A
  • Household fire alarms
  • Irradiating food
  • Sterilisation of equipment
  • Tracing and gauging thicknesses of materials
  • Diagnosis and treatment of cancer
59
Q

State TWO uses of nuclear radiation in the field of medicine.

A
  1. Examining of internal organs
  2. Radiotherapy in the treatment of cancer
60
Q

Why is ionising radiation dangerous?

A
  • It can damage tissue and kill cells
  • It can cause cell mutations
61
Q

What is a consequence of cell mutation?

A

Cancer

62
Q

What precautions should people take when using ionising radiation?

A
  • Avoid handling the source directly (use tongs)
  • Wear radiation protective clothing
  • Keep the radiation in lead containers to reduce the amount of radiation that can escape
  • Keep exposure time to a minimum
63
Q

Does a long half live or a short half life make a source more dangerous?

A

If it has a long half life then it would remain highly radioactive for longer therefore making it more dangerous.

64
Q

What is irradiation?

A
  • The process of exposing a material to nuclear radiation
  • The material does not become radioactive
65
Q

Advantages of nuclear power for generating electricity.

A
  • Do not produce carbon dioxide
  • Readily available
  • Less nuclear fuel to produce same amount of energy as burning fossil fuels
  • Does not contribute to global warming
66
Q

Disadvantages of nuclear power.

A
  • Unpopular - public perceive it as dangerous
  • Security risks - useful to terrorists
  • Expensive to commission and decommission
  • Radioactive waste is difficult to dispose of
  • Risk of nuclear accidents
67
Q

What usually needs to have to induce fission?

A
  • The unstable nuclei must absorb a neutron
  • Spontaneous fission is rare
68
Q

Name a common fissile nuclei.

A

Uranium - 235

69
Q

What are the three main components of the core of a nuclear reactor?

A
  1. Fuel rods
  2. Control rods
  3. Moderator
70
Q

How is the chain reaction in a fission reactor kept under control?

A
  • Control roads are positioned in between the fuel roads
  • The rate of fission is controlled by moving these roads up and down
  • The lower the rods are inserted, the slower the rate of fission
71
Q

What is the role of the moderator in a nuclear reactor?

A

To slow down the neutrons so they are travelling at speeds which allow them to be absorbed by fissile nuclei and cause fission.

72
Q

How is electricity produced in a nuclear power station?

A
  • The reactions release thermal energy
  • The thermal energy is used to boil water and then produce steam
  • This steam is then used to turn a turbine which starts the generator
73
Q

Name two isotopes of hydrogen which are commonly used in nuclear fission.

A

Deuterium and Tritium

74
Q

Which releases more energy, nuclear fission or nuclear fusion?

A

Nuclear fusion.

75
Q

Explain the difficulties of generating energy through nuclear fusion.

A

Fusion requires very high temperatures which in itself,requires large quantities of energy. Currently, the production of fusion results in a net loss of energy.

76
Q

Give an example of where fusion occurs?

A

In the sun - stars use fusion as their energy source

GCSE Physics ⚛️ (15 decks)

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