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Physics Paper 1 > Radioactivity > Flashcards

Radioactivity Flashcards

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1
Q

radiation is a________ or e________ when…..

A

absorbed, emitted when electrons jump between energy levels

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2
Q

what is another word for energy levels

A

shells

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3
Q

what is an energy level

A

fixed distances from the nucleus where electrons orbit

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4
Q

how do electrons jump between energy levels

A

move up energy levels when they absorb energy and they fall to lower energy levels when they emit energy

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5
Q

how are gamma rays emitted

A

when energy is emitted from the nuclei of unstable atoms, where protons and neutrons change energy levels

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6
Q

what are the 5 types of ionising radiation

A

Alpha
Beta +
Beta -
gamma
neutron

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7
Q

what is true about all types of ionising radiation

A

random

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8
Q

what is the structure of an alpha particle

A

helium nucleus (2 protons, 2 neutrons)

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9
Q

what is the structure of beta-particles

A

electron

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10
Q

what is the structure of beta+ particles

A

positron

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11
Q

what is the structure of neutron radiation

A

neutron

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12
Q

what is the ionising and penetrating power of neutron radiation

A

not directly ionising, high penetrating power

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13
Q

what is the ionising and penetrating power of alpha radiation

A

heavily ionising, very low penetrating power

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14
Q

what is the ionising and penetrating power of beta radiation

A

weakly ionising, low penetrating power

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15
Q

what is the ionising and penetrating power of gamma radiation

A

not directly ionising, very high penetrating power

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16
Q

what is needed to stop alpha particles

A

papers

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17
Q

what is needed to stop beta radiation

A

aluminium

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18
Q

what is needed to stop gamma radiation

A

lead

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19
Q

what is background radiation

A

the radiation that is always present and which we are always exposed to

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20
Q

what are 6 sources of background radiation

A

radon gas
ground and buildings
medical
nuclear power
cosmic rays
food and drink

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21
Q

what is radon gas

A

a radioactive gas that is produced when uranium in rocks decays, it is emitted as alpha particles

22
Q

what are 2 methods used to measure radioactivity?

A

photographic film and Geiger muller tube

23
Q

how does a Geiger muller tube work

A

it consists of a tube filled with argon gas, when the radiation enters this tube argon atoms will be ionised and the electrons released will travel through a thin wire to a ratemeter

24
Q

what is the unit for radioactivity

A

becquerel

25
Q

what is a dosimeter and how do they work

A

a device that is used to measure how much radiation someone is exposed to. it consists of a photographic film that darkens when exposed to radiation.

26
Q

why is there an open window on a dosimeter

A

acts as a control so you that the film is working

27
Q

what happens in Beta - decay

A

a neutron in the nucleus of an unstable atom decays to become a proton and an electron, the proton will stay in the nucleus but the electron will be emitted

28
Q

what happens in Beta * decay

A

a proton in the nucleus decays to become a neutron and a positron, the neutron stays in the nucleus but the positron is emitted

29
Q

what is the overall change after beta-decay to an atom

A

mass number does not change but the atomic number increases

30
Q

what is the overall change after beta+decay to an atom

A

mass number does not change but the atomic number decreases

31
Q

what is the overall change to an atom after alpha decay

A

atomic mass decayed by 4, the atomic number reduced by 2

32
Q

what is the overall change to an atom after gamma decay

A

no change

33
Q

what is the overall change to an atom after neutron decay

A

mass reduced by 1

34
Q

what is meant by the activity of a radioactive source

A

the number of atoms that decay every second

35
Q

what is radioactivity measured in

A

becquerel

36
Q

what is half life

A

the time it takes for half the unstable atoms to decay

37
Q

what are some uses of gamma radiation and what an explanation

A

kills cancer cells - beams of gamma rays can be directed at cancer cells to kill them
sterilise equipment
diagnose cancer -can be used in a tracer solution so that it can be taken up by cells that are growing abnormally, and can be detected with a gamma camera
preserve food - food can be irradiated to kill microbes

38
Q

what is the use of alpha articles and how

A

used in smoke alarms - alp0ha particles will ionise and air and form a current but when smoke enters it interrupts the current and makes it fall which will cause a sire to activate

39
Q

what is the use of beta radiation

A

used to control the thickness of the paper

40
Q

why is ionising radiation dangerous to humans

A

the energy transferred by ionising radiation can remove electrons from atoms to very reactive form ions, which can cause mutations in the DNA which can lead to cancer

41
Q

what are 3 precautions people take when dealing with radiation

A
  1. limited time of exposure
  2. wearing protective clothing
  3. increase the distance to radioactive souyrce
42
Q

what is irradiation

A

is ionising radiation from an external radioactive source travelling to the body, it is not breathed in, eaten or drunk

43
Q

what are the 2 types of contamination

A

external and internal

44
Q

what is internal contamination

A

when a radioactive source enters the body

45
Q

what is external contamination

A

occurs when radioactive materials come into contact with a person’s hair, skin or clothing

46
Q

what are 4uses of radiation in medicine

A

medical tracers
PET scanners
treating tumours internally
treating tumours externally

47
Q

what is a medical tracer

A

medical tracers are substances that are used in the biological processing of the body and contain a radioactive substance

48
Q

what is a PET scanner and how do they work

A

PET scanners are used to produce 3D colour images of the internal workings of a patient
1. the tracer is a radioactive material that emits positrons
2. when these positions come into contact with electrons in the body, the 2 particles annihilate each other forming gamma rays
3. these gamma rats are detected by the scanner and processed to form an image

49
Q

how is radiation used to treat tumours internally

A

cancer tumours can be treated internally by using a radioactive source inside the patient. the patient will be injected with a radioactive isotope so that it will be taken up by the cancer cells. the ionising radiation produced will kill the cancer cells

50
Q

how is radiation used to treat tumours externally

A

several beams of gamma rays are fired from different positions towards the cancer cells, while will damaged the cells

Physics Paper 1 (10 decks)

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