Radioactivity Flashcards

1
Q

What is the atomic (Proton) number?

A

Number of protons in a nucleus

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2
Q

What is mass (nucleon) number?

A

Number of proton and neutrons in a nucleus

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3
Q

3 types of radiation are…

A

Alpha and beta particles
Gamma radiation

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4
Q

What makes a nucleus unstable?

A

More neutrons than protons

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5
Q

What word describes the way a radioisotope decays?

A

Random

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6
Q

All types of radiation are capable of ….

A

Ionisation

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7
Q

Describe alpha particles..

A

2 proton 2 neutrons
helium nucleus
highly ionising
low penetrating power
stopped by 5cm of air or paper

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8
Q

Describe beta particles …

A

Very fast electron
medium ionising power
medium penetrating power
stopped by mm of aluminium

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9
Q

Describe gamma….

A

very high frequency electromagnetic radiation
low ionising power
high penetrating power
stopped by thick lead or metres of concrete

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10
Q

Why is alpha highly ionising?

A

large mass
2+ charge

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11
Q

What do you use to detect radiation?

A

GM tube and counter
photographic film

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12
Q

Sources of background radiation…

A

cosmic rays
rocks
food
nuclear waste

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13
Q

Unit of activity is …

A

Becquerels (Bq)

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14
Q

Define half life

A

Time taken for half the radioactive nuclei to decay.
Time taken for activity to fall by half

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15
Q

In an experiment to measure activity, how do you deal with background radiation?

A

measure background before and after the experiment, take a average and subtract it from all readings

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16
Q

Uses of radioactivity

A

treating cancer
sterilising medical equipment
medical tracers
industry tracers
dating articles

17
Q

What is the difference between contamination and radiation?

A

Contamination: radioactive material enters the body
Irradiation: radiation passed through

18
Q

Dangers of radiation

A

mutations in living organisms
damage cells and tissues
problems with disposing of radioactive waste

19
Q

What is fission?

A

Neutron splits a heavy, unstable nuclei, producing 2 daughter nuclei and more neutrons, releasing energy

20
Q

What is fusion?

A

Two light nuclei join to make one heaver one and release Kinetic energy. Energy comes from a loss of mass during fusion

21
Q

2 conditions needs for fusion

A

high temps
high pressure

22
Q

What is a chain reaction?

A

Each fission produces more neutrons which go on to split more nuclei and numbers and energy released build up very quickly

23
Q

What are control rods?

A

Used in a nuclear fission reactor to absorb excess neutrons and limit fission

24
Q

What is a moderator?

A

Slows down neutrons so they can be absorbed by the nuclei to split it

25
What is shielding?
Outer layer of thick concrete and lead to ensure radiation in contained in a nuclear reactor
26
Where does fusion happen naturally?
in the stars
27
Why can't fusion happen at low temps and pressures?
Nuclei are positively charged and so would repel due to electrostatic repulsion