12. P7 Radioactivity Flashcards

1
Q

Name the three types of radiation given out by unstable isotopes?

A

Alpha Beta Gamma

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2
Q

What will stop alpha radiation?

A

Sheet of paper

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3
Q

What beta radiation can be stopped using?

A

3-5mm of Aluminium

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4
Q

What gamma radiation can be stopped using?

A

5-10 cm of lead

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5
Q

What is alpha radiations range in air?

A

up to 5cm in air

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6
Q

What is beta radiations range in air?

A

up to 1m in air

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7
Q

What is gamma radiations range in air?

A

over 1km in air

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8
Q

What is alpha radiation made up of?

A

2 protons and 2 neutrons

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9
Q

What is beta radiation made up of?

A

fast moving electron

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10
Q

What is gamma radiation made up of?

A

Energy (electromagnetic wave)

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11
Q

Which type of radiation is the most highly ionising?

A

Alpha

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12
Q

Which type of radiation travels at the speed of light?

A

Gamma

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13
Q

Which type of radiation is not affected by a magnetic or electric field and why?

A

Gamma as it does not have charge

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14
Q

The charge of an alpha particle?

A

Positive

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15
Q

The charge of a beta particle?

A

Negative

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16
Q

Name of scientist who discovered the electron and put forward the plum pudding model fo the atom?

A

JJ Thompson

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17
Q

What equipment did Rutherfords assistants use in order to test the plum-pudding model?

A

Thin gold foil, microscope with zinc sulphide screen, alpha source in lead shield with narrow opening, all within a vaccuum.

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18
Q

What observations were made from Rutherford’s experiment?

A

1) Most of the alpha particles passed straight through, 2) Few were deflected at small angles, 3) Very few were repelled at large angles(>90degrees) back in the direction of the source

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19
Q

What were Rutherford’s conclusion from the Alpha-scattering experiment?

A

1) Most of the atom is empty space, 2) Contains a small positively charged point which contains most fo the mass.

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20
Q

Where is all radiation emitted from

A

Nucleus of unstable isotope

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21
Q

Why did Rutherford carry out the alpha scattering experiment all within a vacuum?

A

So the air would not affect the path of the alpha particles. Alpha particles are easily absorbed by air and only have a range of upto 5cm.

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22
Q

Name given to the model of the atom which displaced Thompson’s Plum-pudding model after Rutherfords results?

A

Nuclear Model

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23
Q

Name of the scientist who adapted Rutherfords model to include the electrons orbiting around the nucleus and existing in “shells”?

A

Neils Bohr

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24
Q

Name of scientist who found direct experimental evidence for the existence of the Neutron which was found alongside protons in the nucleus?

A

James Chadwick

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25
Q

What does the atomic number of an element tell us?

A

The number of protons in the nucleus

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26
Q

What does the mass number of an element tell us?

A

The number of protons and neutrons in the nucleus.

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27
Q

What is meant by an isotope?

A

An element with the same number of protons but different number of neutrons.

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28
Q

What happens to the proton number when an unstable isotope emits an alpha particle?

A

Goes down by 2

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29
Q

What happens to the proton number when an unstable isotope emits an beta particle?

A

Goes up by 1

30
Q

What happens to the proton number when an unstable isotope emits an gamma particle?

A

Stays the same

31
Q

What happens inside the nucleus during beta decay?

A

Neutron decays into a proton, emitting an electron.

32
Q

What is meant by radiation being ionising?

A

Can collide/interact with other atoms and remove electrons from their shells, causing the atom to become charged.

33
Q

What can happen if ionisation takes place in living cells?

A

Cells damage (or kill it), which can lead to cell mutation and cancerous growths.

34
Q

What is meant by radioactive contamination?

A

When a radioactive source comes in contact with another object/surface.

35
Q

Which is the most dangerous type of radiation inside the body?

A

Alpha, as all the ionisation takes place inside the body as alpha can not pass through it.

36
Q

What safety precautions should be taken when dealing with radioactive sources?

A

Wear the necessary protective clothing and goggles, handle using tongs(no direct contact), limit time spent handling/in same area of the radioactive source

37
Q

What is the name given to the process where other scientists check the work and findings of another scientist?

A

Peer review

38
Q

Which type of radiation emitting isotope would be used in smoke alarms?

A

Alpha emitting isotope

39
Q

Which type of radiation emitting isotope would be used for industrial tracing like finding leakages in underground water pipes for example?

A

Gamma emitting isotope

40
Q

Which type of radiation emitting isotope is used in production lines for controllign the thickness of aluminuim foil?

A

Beta emitting isotope

41
Q

Explain how radiation can be used to control the thickness of the aluminium foil?

A

If the foil becomes too thin, more beta radiation passes through the foil so the detector detects a greater signal. This is fed back through a computer, which decreases the pressure on the rollers.

42
Q

What is the unit for activity of a radioactive source?

A

Becquerel (Bq)

43
Q

What is meant by the activity of a radioactive source?

A

It is the number of decays per second.

44
Q

What device can you use to measure the amount of radiation given out by a radioactive source in a certain direction?

A

Geiger counter.

45
Q

What monitoring device do all people working with radiation have to wear?

A

Radiation badge

46
Q

What is meant by the half-life of a radioactive source?

A

It is the time taken for the activity(or the number of radioactive particles present) to drop by half.

47
Q

What is meant by the random nature of radioactive decay?

A

That radiation can not be predicted. You can not tell which atom will decay next or increase (or slow)down the rate at which radioactive sources decay.

48
Q

Which type of radiation emitted does not change the type of atom the isotope is?

A

Gamma

49
Q

How many half-lives would it take for the activity of a radioactive source to drop to 25% of its original level?

A

2 half-lives

50
Q

Which type of radiation would be used for a medical tracer, such as checking kidney function? (PHYSICS ONLY)

A

Gamma

51
Q

Which type of radiation would be used during radiotherapy to kill cancerous cells such as brain tunours? (PHYSICS ONLY)

A

Gamma

52
Q

Why is radioactive iodine used to check the kidney function of a patient? (PHYSICS ONLY)

A

HL = 8 days, emits gamma radiation, decays into a stable product

53
Q

What factors do you have to consider for when chossing a radiactive isotope as a medical tracer? (PHYSICS ONLY)

A

The half-life, and the type of radiation emitted by it.

54
Q

Where does 50% of the background radiation come from? (PHYSICS ONLY)

A

air (radon gas that seeps from ground from radioactivity rocks)

55
Q

Where does the background radiation around us come from? (PHYSICS ONLY)

A

radon gas, medical, ground, food and drink, cosmic rays,

56
Q

Explain what is meant by nuclear fission? (PHYSICS ONLY)

A

The splitting of an atoms nucleus into two smaller nuclei, releasing energy and neutrons in the process.

57
Q

What fuel is used in nuclear power stations? (PHYSICS ONLY)

A

Uranium and Plutonium

58
Q

What is required to start the nuclear fission process in Power stations? (PHYSICS ONLY)

A

Absorbption of an neutron by the nucleus.

59
Q

What percentange of U-235 is required for the fuel rod to be fissionable and undergo a successful chain reaction? (PHYSICS ONLY)

A

3%

60
Q

What do the control rods do in a nuclear reactor? (PHYSICS ONLY)

A

The can be lowered to slow down the rate of reaction.

61
Q

What is the role of the moderator in a nuclear reactor? (PHYSICS ONLY)

A

It slows down the fission neutrons released during fission so they can be absorbed by further nuclei.

62
Q

What material is the nuclear reactor core made out of and why? (PHYSICS ONLY)

A

Steel to withstand the high temperatures and pressure

63
Q

What is the metal nuclear reactor enclosed in and why? (PHYSICS ONLY)

A

Thick concrete walls to absorb any radiation which escapes through the reactor walls.

64
Q

What is meant by nuclear fusion? (PHYSICS ONLY)

A

It is when two smaller nuclei join together to form a larger nuclei.

65
Q

What is the majority of fusion taking place in stars? (PHYSICS ONLY)

A

Hydrogen fuses with Hydrogen to form Helium

66
Q

Why is fusion a difficult process to manage outside of stars? (PHYSICS ONLY)

A

High temperatures are required, so the two nuclei are moving fast enough to overcome the repusive force due to both being positively charged.

67
Q

In a nuclear fusion reactor, how is the plasma heated to get to the high temperatures required? (PHYSICS ONLY)

A

Using electric currents.

68
Q

Why does radioactive waste need to be stored securely? (PHYSICS ONLY)

A

It remains radioactive so needs to be carefully stored to prevent contamination into the environment.

69
Q

Why does radioactive waste need to be stored for many years? (PHYSICS ONLY)

A

It remains radioactive for a long time as it has a very long half life.

70
Q

How is high level nuclear waste stored after decommisioning a nuclear power station? (PHYSICS ONLY)

A

Under ground in large water tanks to keep them cool.

71
Q

What are the units which background radiation is measured in? (PHYSICS ONLY)

A

Sv (sieverts)