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GCSE Physics Paper 1 (Motion )+ (Radioactivity) + (Astronomy) > TOPIC 6 Radioactivity (Extra apart from School made) > Flashcards

TOPIC 6 Radioactivity (Extra apart from School made) Flashcards

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1
Q

What is the structure of an atom?

A

Positively charged nucleus with protons and neutrons
Surrounded by orbits of negatively charged electrons
OVERALL NEUTRAL CHARGE

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2
Q

Where is most of the mass in an atom found?

A

In the nucleus

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3
Q

How big is the nucleus of an atom compared to the size of the atom?

A

100,000 times smaller.

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4
Q

What is an isotope?

A

An atom of the some element with different mass (nucleon) number but the same atomic (proton) number.

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5
Q

How is an isotope different to an element, in terms of its subatomic particles?

A

An isotope will have more or less neutrons than the element.

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6
Q

What are the charges of: protons, neutrons and electrons?

A

Proton: +1
Neutron: 0
Electron: -1

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7
Q

What makes electrons move between shells?

A

Losing or gaining the right amount of energy (electro magnetic)
Gaining energy- move AWAY from nucleus
Losing energy- moving TOWARDS the nucleus

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8
Q

How do atoms form positive ions?

A

Losing a certain amount of outer shell electrons.

eg: +2 charge has lost 2 electrons

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9
Q

What is background radiation?

A

Ionising radiation, at a low, safe level from space and naturally radioactive substances in the environment.

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10
Q

What produces background radiation around us? (Mention Main source)

A 
Radon gas (Main)
Cosmic rays
Food and drink
Buildings
Naturally in soil, seas etc
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11
Q

How can radiation be detected (2 methods)?

A

Geiger-Müller Tube

Radiation dosimeter

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12
Q

How does a Geiger-Müller Tube work?

A

Contains a counting circuit and space full of particles
Radioactive substance enters and bumps into a particle, releasing an electron
The electron is attracted to the positive counting circuit , creating a measurable current

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13
Q

What 3 types of radiation do unstable nuclei emit?

A

Alpha
Beta (+/-)
Gamma

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14
Q

Can we predict when unstable nuclei will decay?

A

No, it is a random process

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15
Q

What type of radiation are alpha, beta and gamma radiation?

A

Ionising radiation

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16
Q

What is the charge on an alpha particle?

A

+2

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17
Q

What is the mass on an alpha particle?

What type of atom is an alpha particle the same as?

A

4 mass units

Helium atom (mass=4, proton number= 2)

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18
Q

How ionising is an alpha particle?

A

Highly ionising

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19
Q

During Alpha Decay, how does:

  • the mass number change
  • the atomic number
A

Mass number- decrease by 4

Atomic number- decrease by 2

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20
Q

What is the charge on a beta particle?

A

-1

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21
Q

What is the mass of a beta particle?

A

1
—
1850 mass units

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22
Q

What happens during beta minus decay?

A

A neutron changes to a proton and a high speed electron is ejected from the nucleus
0 e
-1

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23
Q

What happens to the atom during beta minus decay (subatomic particles)?

A

Atomic number increases by 1

Mass umber doesn’t change

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24
Q

What happens during beta plus decay?

A

Proton becomes a neutron and a positron (positive charge)

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25
Q

What happens during beta plus decay (subatomic particles)?

A

Decreases the atomic number by 1

Leaves mass number unaffected

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26
Q

What happens during gamma decay (subatomic particles)?

A

Both atomic and mass number remain unaffected.

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27
Q

What is activity?

A

How many decays happen per second (rate of decay)

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28
Q

What is activity measured in?

A

Becquerels

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29
Q

What is 1 Bq mean?

A

1 nuclear decay per second

30
Q

What is the half time?

What is the acronym to remember this?

A

The time for activity of a sample to half

TASH

31
Q

Which has a higher activity:

Substance with a shorter half life
Substance with a longer half life

A

Shorter half life- quickest to half it’s life

32
Q

How is radioactivity used for the diagnosis and treatment of cancer?

A
  • Tracers using a beta emitter during INTERNAL RADIOTHERAPY like iodine-131 placed inside body/close to tumour
  • EXTERNAL RADIOTHERAPY - beams of gamma rays directed at tumour from outside of body
  • Lower strengths beams from around tumour to harm tissue around it as little as possible
33
Q

How is radioactivity used to irritate food?

A
  • Gamma Rays kill bacteria
  • Allows food to be stored for longer/safe to eat

-Surgical Equipment is also irradiated using heat from gamma rays (sterilise)

34
Q

How do smoke detectors use radioactivity?

A

H

35
Q

How is radioactivity used to monitor the thickness of paper?

A
  • Paper is made by squeezing wood pulp between rollers
  • Squeeze harder for thinner paper
  • Beta particle detector is used- if it penetrates the paper, count rate is higher and rollers apply less pressure
36
Q

How is radioactivity used to detect leaking pipes?

A
  • Gamma source is added to water in pipes underground
  • When leaking, the water flows into the surrounding Earth
  • Geiger-Müller Tube follows pipe’s path and detect where pipe is leaking (higher radiation)
37
Q

What is contamination?

A

When someone gets particles of radioactive material on their akin/inside their body.
This can also happen to water or soil

38
Q

What is irradiation?

A

When someone is exposed to alpha, beta or gamma radiation from nearby sources. The irradiation stops when they move away.

39
Q

How are radioactive sources handled by people working with them?

A

With tongs, to increase the distance from the body

40
Q

How are radioactive sources stored, where people work?

A

eg: Hospital- Always stored in boxes lined with lead

41
Q

How are people dealing with radioactive substances monitored?

A

By wearing a dosimeter badge- measures levels of radiation

42
Q

How are cancer patients protected from harm by radiation?

A

The lowest possible dose is used

The patient is exposed for the minimum amount of time

43
Q

What is a tracer? (medicine)

A

Usually a substance that is used by the body (eg: glucose) attached to a radioactive substance.

44
Q

Why are tracers used?

A

Different parts of the body absorb different types of tracers.
This helps to diagnose problems in different areas of the body.

45
Q

Give an example of a tracer and it’s use.

A

Any from:

Technetium-99 - attached to drug that collects in the brain

Iodine-123 - absorbed by thyroid gland

Krypton-81m - inhales to investigate lung function

Iodine-125 - made into a compound excreted by the kidneys

Indium-111 - attached to whit blood cells to locate infection

46
Q

What are gamma cameras used for?

A

Used to detect highest area of radiation

eg: internal bleeding, tumour

47
Q

How are positrons used in medicine (hint: tracers)?

A

1) Tracer is injected into patient
2) Tracer emits POSITRONS.
3) When each positron interacts with an electron, both are destroyed
4) This causes 2 gamma rays to be emitted in opposite directions
5) These gamma rays are detected by a PET scanner, which moves around the patient + detects the rays produced

48
Q

How does a PET scan show active areas of an organ?

A

Active areas of the organ take up more tracer and appear BRIGHTER.

49
Q

How does internal radiotherapy work?

A
  • Beta emitter like iodine-131 placed in body/very close to tumour
  • Doesn’t always require surgery-p but the patient must be alone while the source is in place
50
Q

How does external radiotherapy work?

A
  • Beams of gamma rays, X-Rays or protons directed at tumour from outside the body
  • Several loser strength beams may be directed from different angles too
  • Tissue absorbs less, tumour absorbs more
51
Q

Why do levels of radioactivity decrease over time?

A

More unstable nuclei decay = the activity of a radioactive source will also decay

52
Q

Why are the nuclei formed after a fission reactions slightly lighter than the nucleus from before?

A

The nuclei have broken up in smaller nuclei and lost some mass as energy.

53
Q

List 3 PROS of nuclear power stations/energy

A

Any 3 from:

  • Store a lot more energy by kg than any other fuel
  • Don’t need air to release energy
  • Don’t produce CO2
  • Estimated to last longer than other fuels
  • Designed for safety
54
Q

List 3 CONS of nuclear power stations/energy.

A

Any 3 from:

  • Produce waste that will remain radioactive for millions of years
  • Waste is expensive to treat
  • Parts of power stations come radioactive as it is used- expensive to decommission
  • Accidents - risk to people
  • Many people believe nuclear power stations are bad
55
Q

What is nuclear fission?

A

The process of splitting a nucleus
Releases large amounts of energy
Used in nuclear power stations

56
Q

Which two isotopes are usually used in nuclear reactors as fuel?

A

Uranium-235 or plutonium-239

Both have relatively large nuclei- easy to split when hit by neutrons

57
Q

What are the stages of nuclear fission?

A
  • Isotope hit by a neutron
  • Splits into 2 smaller daughter nuclei (radioactive)
  • Three more neutrons are released
  • Energy is released- kinetic and thermal
  • This process continues - CHAIN REACTION
58
Q

What is nuclear fusion?

A

A nuclear reaction, in which lighter nuclei are combined together to form heavier product nuclei, with the release of enormous amounts of energy

59
Q

What happens during nuclear fusion?

A

Isotopes (eg: of Hydrogen) fuse together and release energy and a neutron

60
Q

Where do stars use nuclear fusion?

A

In their core

61
Q

Which isotopes do stars use for nuclear fusion?

A

Hydrogen isotopes (eg: Tritium, Deuterium)

62
Q

What does the temperature need to be like for nuclear fission to occur?

A
  • Really high temperatures (millions of degrees)
  • If not, particles will collide and rebound - ELECTROSTATIC REPULSION (protons in nucleus repel)
  • If high enough, the particles have enough kinetic energy to overcome their repulsion and fuse
63
Q

What should the density be like for nuclear fusion to occur?

A

High density

-At the core, gravitational fields are higher, making collisions more likely to happen

64
Q

How does a chain reaction occur (nuclear fission)?

A

1) A slow- moving neutron is fired at an unstable, large nuclei- often uranium-235. The neutron is absorbed by the nucleus. This makes the atoms more unstable, leading it to split up again.
2) When U-235 splits, it forms two lighter elements and energy is released.
3) These daughter nuclei can be lots of different products but all of them are radioactive.
4) Each times uranium atom splits up, it also spits out 2 or 3 neutrons, which hit more uranium nuclei and so on….. causing a chain reaction.

65
Q

What’s special about the neutrons in a chain reaction?

A

They contain a lot of energy

66
Q

At what speed must neutrons be at to cause a chain reaction?

What are these neutrons called

A

Slow speed

Thermal neutrons

67
Q

How are the speed of neutrons in a reactors controlled?

A

Uranium fuel rods are placed in a moderator (eg:graphite) to slow down the fast-moving neutrons

68
Q

What do control rods do in a reactor?

A

Limit the rate of fission by absorbing excess neutrons.

They are placed in between the fuel rods and raised and lowered to control the chain reaction, crating a steady state of nuclear fission.

69
Q

What would happen if the chain reaction ina nuclear reactor was left unchecked?

A

Large amounts of energy would be released in a wry short a,punt of time.
Many new fissions will follow each fission- runaway reaction- explosion.

70
Q

How does a nuclear reactor function (different parts/stages)?

A

1) They are powered by NUCLEAR REACTORS- create controlled chain reactions.

2) Energy released by fission is transferred to the thermal energy store of the MODERATOR, then the thermal energy store of the COOLANT, then to the thermal energy store of the cold water passing through the BOILER.
Water boils- energy is transferred to kinetic energy of the steam

3) Energy is transferred to the kinetic energy store of the TURBINE and to the kinetic energy store of the generator.
The energy is transferred away from the GENERATOR electrically.

GCSE Physics Paper 1 (Motion )+ (Radioactivity) + (Astronomy) (7 decks)

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