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Physics > Unit 4- Atomic Structure > Flashcards

Unit 4- Atomic Structure Flashcards

1
Q

Who discovered the electrons

A

Jj Thompson

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2
Q

What discovered the atom

A

John dalton

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3
Q

Who discovered the plum pudding model

A

Jj Thompson

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4
Q

Who discovered the nuclear model

A

Rutherford

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5
Q

What are alpha particles

A

Helium nuclei (2 neutrons and 2 protons)

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6
Q

What are beta particles

A

Fast moving electron ejected from the nucleus

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7
Q

What are gamma waves

A

Waves of electromagnetic radiation

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8
Q

What is alpha stopped by

A

Paper

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9
Q

How is alpha particles used in homes and how does it work

A

Smoke detectors, ionises air particles causing a current to flow. If there is smoke in the air, it binds to the ions, meaning the current stops and the alarm sounds

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10
Q

Mass and charge of a beta particle

A

No mass
Charge of -1

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11
Q

Penetration and ionising of an alpha particle

A

Doesn’t penetrate far
Strongly ionising

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12
Q

Ionising and penetration of beta particle

A

Moderately ionising
Moderate penetration

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13
Q

What is a beta particle stopped by

A

Sheet of aluminium

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14
Q

What happens when a beta particle is emitted

A

A neutron in the nucleus has turned into a proton

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15
Q

Applications of a beta particle

A

Used to test thicknesses of sheets of metals, as the particles are not immediately absorbed by the material like alpha radiation would do and it doesn’t penetrate as far as gamma rays.

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16
Q

What is gamma rays stopped by

A

Thick sheets of lead

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17
Q

What is the penetration and ionising of gamma rays

A

Penetrate far into materials, weak ionising

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18
Q

What does alpha decay do

A

Atomic number reduces by 2
Mass number reduces by 4
Charge of the nucleus descreases

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19
Q

What is the mass number

A

Big number

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20
Q

What is the atomic number

A

Small number

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21
Q

What does beta decay do

A

Atomic number increases by 1

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22
Q

What is half life

A

Time taken for the number of radioactive nuclei in an isotope to halve

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23
Q

Example of a detector that can be used to detect radiation

A

Geiger- muller tube

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24
Q

Describe mass number in terms of atoms

A

Total number of protons and neutrons in nucleus

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25
Q

What does gamma decay do

A

Mass and atomic number does not change

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26
Q

Risks to radiation

A

High doses can kill cells completely causing vomiting, tiredness and radiation sickness
Lower doses tend to cause minor damage without killing cells. This can increase the mutant cells which divide uncontrollably causing cancer.

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27
Q

What is nuclear fission

A

Nuclear reaction used to release energy from large unstable atoms (uranium, plutonium) by splitting them into smaller atoms

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28
Q

Process of nuclear fission

A
  • neutron is absorbed
  • nucleus splits into smaller nuclei
  • releasing energy and gamma rays
  • and two or three neutrons
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29
Q

How is the energy produced in fission controlled

A

Done using control rods which when lowered or raised inside a nuclear reactor, absorb neutrons

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30
Q

Name sources of background radiation

A

Natural = rocks(granite) cosmic rays(high energy)
Man made = fall out from nuclear weapons testing, nuclear accidents

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31
Q

What is irradiation

A

Exposure to radiation

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32
Q

What is contamination

A

Radioactive particles getting onto objects, comes from touching and handling radioactive substances.

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33
Q

What is nuclear fusion

A

Joining of small nuclei to create a larger heavier nucleus (opposite of fission)

34
Q

Process of nuclear fusion

A
  1. Two light nuclei collide at high speed and join (fuse)
  2. Create a larger heavier nucleus
  3. This could be a hydrogen nuclei fusing to produce a helium nuclei
  4. Fusion releases a lot of energy
35
Q

How is radiation used to treat cancer

A

During radiotherapy, gamma rays are directed carefully to kill the cancer cells without damaging normal cells

36
Q

What is the unit for the activity of a source

A

Becquerels

37
Q

What does a step up transformer do

A

Increases potential difference and decreases current, therefore reducing thermal energy transfer to surroundings increasing efficiency

38
Q

What does a step down transformer do

A

Decreases potential difference so it is at a safer value

39
Q

What is meant by random nature of radioactive decay

A

Can’t predict when a nucleus will decay

40
Q

A negatively charged student touches a tap and receives an electric shock. Why?

A

Potential difference between student and tap.
Which causes electrons to transfer
Which earths the charge

41
Q

How to work out count rate

A

Counts / time in seconds

42
Q

How to work out activity

A

Becquerels x mass

43
Q

One reason why the bananas equivalent dose will help public be more aware of radiations risks

A

People are able to compare a radiation risk to radiation from bananas

44
Q

Explain how resistance of filament lamp changes as potential difference increases

A
  • current increases as p.d increases
    -which causes temp to increase
    -so resistance increases
45
Q

Why does the alarm switch on when the smoke particles enter the plastic casing

A

Smoke stops alpha radiation

46
Q

Why is it safe to use alpha radiation in a house

A

Doesn’t penetrate very far

47
Q

Why would a smoke alarm not work with beta or gamma

A

Beta and gamma will penetrate smoke
So no change in count rate will be detected

48
Q

Explain ideal properties of a radioactive source for medical diagnosis

A

-short half life so less damage to cells
- low ionising power so less damage to cells
-high penetration so can be detected outside the body

49
Q

2 reasons why taking repeat readings could provide more accurate data

A
  • remove anomalies
  • calculate a mean
50
Q

fuels used in nuclear power station

A

Uranium, plutonium

51
Q

Why is it dangerous for live wire to touch metal cable

A

Risk of electric shock

52
Q

What is the potential difference of the live wire

A

230 volts

53
Q

Potential difference of neutral wire

A

Zero

54
Q

Potential difference of earth wire

A

0 volts

55
Q

Why will a person get an electric shock from the live wire

A

The potential difference of the live wire is 230 v and the potential difference of the person is 0v therefore there is a large potential difference so charge will pass through their body causing an electric shock

56
Q

Most appropriate fuse rating for a television/ toaster

A

3A

57
Q

When two insulators rub against each other what happens

A

Electrons pass from one to the other

58
Q

Radius of atom

A

1 x 10 to the minus 10

59
Q

Radius of nucleus

A

1 x 10 -14

60
Q

In an atom where is the energy level highest

A

The further from the nucleus the higher the energy

61
Q

What is the mass number

A

Number of protons + number of neutrons

62
Q

What is the atomic number

A

Number of protons or electrons

63
Q

What was the first subatomic particle to be discovered

A

Electron

64
Q

What is the plum pudding model

A

Ball of positive charge with negative electrons embedded in it

65
Q

Conclusions from alpha scattering experiment

A

-Most of alpha particles went straight through gold foil therefore atoms are mainly empty space
-some particles were deflected therefore centre of atom much have a positive charge

66
Q

What did James Chadwick discover

A

Neutrons

67
Q

What is radioactive decay

A

Some isotopes have unstable nucleus so to become stable they give out radiation

68
Q

What is activity in radioactive decay

A

The rate at which a source of unstable nuclei decay, measured in Becquerel

69
Q

What is count rate

A

Number of decays recorded each second by a detector

70
Q

Alpha range in air

A

5cm (low )

71
Q

Beta range in air

A

15cm (medium)

72
Q

Gamma range in air

A

Several meters (high)

73
Q

How is gamma used to sterilise medical equipment

A

-place object in plastic wrapper to stop bacteria entering
-place object near radioactive isotope which emits gamma
-place lead shield in front to protect workers from radiation

74
Q

Ways to protect against radiation

A

Alpha = gloves
Beta = lead apron
Gamma = lead apron
Use radiation monitor to measure how much radiation has been received

75
Q

Dangers of alpha radiation

A

Strongly ionising but easily stopped by dead cells on skin surface, can be dangerous if inhaled or swallowed

76
Q

Dangers of beta radiation

A

Quiet ionising and can penetrate into the body

77
Q

Dangers of gamma radiation

A

Weak ionising can penetrate into the body but likely to pass back out again

78
Q

What is peer review

A

Scientists review each other’s conclusions from new scientific research. They also check the method used and the accuracy of the results

79
Q

What affects how much background radiation you receive

A

Location and occupation

80
Q

What is the dose of radiation measured in

A

Sieverts

81
Q

Conditions for internal organs traced

A

-Must emit radiation that can pass out of the body and detected
-Tracer must not be strongly ionising to minimise damage to body tissue
-Must have short half life so not present in body for too long
-must not decay into another radioactive isotope

82
Q

What happens to the neutrons after nuclear fission

A

They can then be re absorbed by another nuclear nuclei and trigger fission again this is called a chain reaction

Physics (6 decks)

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