Paper 1 - Radioactivity And Particles Flashcards

1
Q

What is the definition of Half-Life?

A

The time it takes for the count rate of a radioactive source to fall to half its original count rate

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2
Q

Describe the nature of alpha particles

A
  • Stopped my air or paper
  • Stronger affected by magnetic fields
  • Heaviest particle
  • Heavily charged
  • Least penetrating power
  • Most ionising
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3
Q

What is meant by atomic number?

A

The number of protons in the nucleus

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4
Q

Describe uses of radioactivity in medicine

A
  • Gamma rays used to sterilise medical equipment
  • Gamma rays can be used to target and destroy cancer cells
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5
Q

What happens to a radioactive source over time?

A

Activity (measured in Becquerels) decreases over time

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6
Q

What is meant by mass number?

A

The sum of the number of protons and neutrons in a nucleus

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7
Q

Describe the effects of neutron emission on the atomic and mass numbers of an atom

A
  • Atomic number : no change
  • Mass number : decreases by 1
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8
Q

Describe the structure of an atom in terms of protons, neutrons and electrons

A
  • An atom has a nucleus containing protons and neutrons with an overall positive charge
  • And gas orbital electrons, surrounding the nucleus in shells
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9
Q

What is background radiation?

A
  • Radiation that is all around us at all times at a safe level
  • Measured in Becquerels
  • Includes alpha, beta and gamma radiation
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10
Q

What are the sources of background radiation and are they natural or artificial?

A
  • Cosmic rays - natural
  • Radon gas - natural
  • Food and drink - artificial
  • Nuclear weapon testing - artificial
  • Nuclear power stations - artificial
  • Medical - artificial
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11
Q

Describe the effects of Gramma emission on the atomic and mass numbers of an atom

A
  • Atomic number : no change
  • Mass number : no change
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12
Q

What is meant by isotope?

A
  • Same number of protons
  • Different number of neutrons
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13
Q

What can vary between different radioactive isotopes?

A

Half-Life

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14
Q

What is the difference between contamination and irritation?

A
  • contamination is when a non-radioactive object comes into contact with a radioactive material
  • irradiation is when radiation is present
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15
Q

Describe the effects of Beta emission on the atomic and mass numbers of an atom

A
  • Atomic number : Increases by 1
  • Mass number : no change
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16
Q

What are the issues with disposing of radioactive waste?

A
  • Elements like Plutonium and Uranium have incredibly long half-lives and therefore will emit dangerous levels of radiation for a long term
  • Which has an effect on plant and animal life
17
Q

What are the dangers of ionising radiations?

A
  • Radiation can cause mutation in living organisms
  • Radiation can damage cells and tissues
  • There are problems with the disposal of radioactive waste
18
Q

Describe the nature of Gamma particles

A
  • Most penetrative
  • Least ionising
  • Passes through aluminium but not lead
  • Not a particle so has no charge or mass
  • Pure energy
19
Q

Describe uses of radioactivity in industry

A
  • Can be used in smoke detectors
  • Can be used in thickness detectors
  • Can be used for nuclear weapons
  • Can be used for radioactive tracers
  • Can be used for leak detectors
20
Q

What are alpha, beta and gamma rays?

A

Ionising radiations emitted from unstable nuclei in a random process

21
Q

Describe the effects of Alpha emission on the atomic and mass numbers of an atom

A
  • Atomic number - decreases by 2
  • Mass number : decreases by 4
22
Q

Describe the nature of Beta particles

A
  • More penetrative than alpha, less penetrative than gamma
  • Lighter than alpha
  • Negative charge
  • Stopped by aluminium or thin plastic
23
Q

What can photographic film or a Geiger-Muller detector do?

A

Detect ionising radiations

24
Q

What can nuclear reactions including fission and fusion be?

A

Sources of energy

25
How is a nucleus of Uranium-235 split?
- The process of fission - Neutron collides with Uranium-235 atomic - This releases energy as kinetic energy of the fission products
26
What does the fission of Uranium-235 produce?
- 2 radioactive daughter nuclei - A small number of neutrons
27
How can a chain reaction be set up if the neutrons produced by one fission strike other Uranium-235 nuclei?
In fission, a neutron from a previous decay can lead to more and more decays
28
Describe the role played by the control rods and moderator in the fission process
- Control rods soak up excess neutrons, preventing the chain reactions from getting out of control, otherwise, this could lead to a nuclear disaster - The moderator functions to slow down the neutrons
29
What is nuclear fusion?
The creation of larger nuclei resulting in a loss of mass from smaller nuclei, accompanied by a release of energy
30
What is fusion the energy source for?
Stars
31
Explain why nuclear fusion does not happen at low temperatures and pressures, due to electrostatic repulsion of protons
- At low temperatures/pressures, the positively charged protons will repel from each other - When moving slowly, the particles do not have enough kinetic energy to overcome the electrostatic forces of repulsion so cannot fuse
32
Explain the difference between nuclear fusion and nuclear fission
- Fission is a chain reactions, Fusion is not - Fusion is the joining of nuclei whereas Fission is the splitting of nuclei
33
What is the role of Shielding around a nuclear reactor?
To absorb hazardous radiation (daughter nuclei)
34
What are the products of the fission of uranium nuclei?
- neutrons - daughter nuclei - thermal energy