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Physics > P4 > Flashcards

P4 Flashcards

1
Q

what are the 3 particles in an atom?

A

protons, neutron and electrons

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2
Q

where are protons, neutrons and electrons found?

A

protons & neutron: in the nucleus
electrons: in the shells

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3
Q

what happens when 2 of the same charged particles experience a force?

A

they repell

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4
Q

what happens when 2 of opposite charged particles experience a force?

A

they attract

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5
Q

what is the relative charge of a proton?

A

positive +1

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6
Q

what is the relative mass of a proton?

A

1

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7
Q

what is the relative charge of a neutron?

A

neutral, 0

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8
Q

what is the relative mass of a neutron?

A

1

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9
Q

what is the relative charge of an electron?

A

negative, -1

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10
Q

what is the relative mass of an electron?

A

1/2000th

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11
Q

what is the charge of an atom? why?

A

they are neutrally charged
-bcus their no. of protons = no. of electrons

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12
Q

what is the overall charge of the nucleus?

A

positive

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13
Q

equation: relative mass of an atom

A

protons+ neutron

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14
Q

what is the atomic number?

A

number of protons

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15
Q

what is the mass number?

A

protons + neutrons

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16
Q

what are isotopes?

A

atoms with the same number of protons but different number neutron

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17
Q

what is ionisation?

A

the process in which an atom becomes an ion

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18
Q

what is excitation?

A

when energy is provided by light and en electron goes to a higher energy level

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19
Q

n.d what is relaxation?

A
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20
Q

what are 2 reasons for ionisation? Check

A
  1. another electron rushes past the atom with lots of energy and collides, with the atom and gives some of its energy within the atom and the electron has enough energy to escape

2, light of enough energy strikes the atom (e.g ultraviolet light)

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21
Q

what did Democritus come up with in 400BC?

A

everything is composed of atoms

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22
Q

what did John Dalton come up with? in what year?

A
  1. all matter is composed of atoms
  2. atoms can’t be subdivided or destroyed
    - 1803
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23
Q

what did JJ Thompson come up with? what year?

A

The Plum Pudding Model
- 1904

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24
Q

what 3 things does the plum pudding model consist of?

A
  1. a positive ‘blob’
  2. negatively charged electrons scattered inside
  3. removing an electron made an ion
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25
Q

give 3 characteristics of Alpha particles

A
  1. positively charged
  2. light weight
  3. fast
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26
Q

what happens to the Fluorescent screen when alpha particles hit it?

A

it glows

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27
Q

Give 3 results of the alpha particles experiment

A
  1. most of the alpha particles passed straight through
  2. some would be deflected/ change direction
  3. a few would bounce back
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28
Q

what did it mean when most of the alpha particles went straight through?

A

means atoms are mostly empty space

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29
Q

What did it mean when some of the alpha particles deflected/ changed direction?

A

it meant the centre of the atoms are positively charged

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30
Q

what did it mean when a few alpha particles bounced straight back?

A

the centre of the atom is very small and dense, with a positive charge

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31
Q

what charge do alpha particles have?

A

positive

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32
Q

what charge does a gold atom have?

A

no charge, it’s neutral

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33
Q

what is the plum pudding model.

A

a ball of positive charge with negative electrons randomly embedded

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34
Q

what are 2 main changes to the atomic model the alpha scattering experiment resulted in?

A

mass: concentrated in the centre
charge: positive charge at the centre

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35
Q

who discovered the 1st chemical element?

A

Marie Curie

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36
Q

What did Marie Curie name the first chemical element?

A

Polonium
- after Poland

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37
Q

When does Radioactivity occur?

A

when the nucleus of an atom is unstable

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38
Q

what are the 4 types of nuclear radiation?
- order they were discovered

A

Alpha
Beta
Gamma
Neutron

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39
Q

what is alpha radiation made from?

A

2 protons and 2 neutrons
- comes out the nucleus very fast –> has lots of energy

40
Q

What is beta radiation?

A

a high speed electron from the nucleus of an atom

41
Q

what is gamma radiation? (5)

A

are waves of electromagnetic radiation from the nucleus
- high energy
- are a family of radiation
- don’t have mass
- not real particles

42
Q

penetrating meaning?

A

able to make a way through or into something.

43
Q

describe the penetrating power of an alpha radiation? what is it stopped by?

A

low penetrating power
- stopped by small/thin stuff (e.g piece of paper)

44
Q

describe the penetrating power of beta radiation? what is it stopped by?

A

medium penetrating power
- stopped by a few mm of aluminium, copper, steel

45
Q

describe the penetrating power of gamma radiation? what is it stopped by?

A

high penetrating power
- blocked by thick lead or concrete

46
Q

what would a strong gamma radiation require for it to penetrate?

A

thicker lead or concrete

47
Q

describe alpha radiation’s range in air?

A

few cm (1-4cm)
- can be measure with ruler
- has large particles so only travel few cm before alpha particles collide with air molecules and give up their energy

48
Q

describe beta radiation’s range in air?

A

range is long (1-2 metres)
- measure with tape metre
- travel few metre before beta particles collide with airmolecules

49
Q

why is alpha radiation and beta radiation range in air lower?

A

because their particles collide with air molecules
and give up their energy

50
Q

describe gamma radiation’s range in air?

A

long range
(10- billions of kilometres)

51
Q

describe the ionising power of alpha radiation

A

has a high ionising power
- because has a charge of +2

52
Q

describe the ionising power of beta radiation

A

medium ionising power
- because has a charge of -1

53
Q

describe the ionising power of gamma radiation

A

has a low ionising power
- because has a neutral charge

54
Q

what does more charge or more energy mean in terms of ionising power?

A

higher ionising power

55
Q

Alpha radiation (3)
(Penetrating/ionising power, range in air rank)

A
  1. least penetrating power
  2. most ionising power
  3. least range in air
56
Q

beta radiation (3)

A
  • 2nd most penetrating power
  • 2nd most ionising power
  • 2nd longest range in the air
57
Q

gamma radiation (3)

A
  1. most penetrating power
  2. least ionising power
  3. greatest range in the air
58
Q

when are alpha, beta, gamma radiation the most hazardous?

A

alpha: in short range
beta: in mid- range
gamma: in long range

59
Q

what is a gamma ray?

A

a type of electromagnetic radiation

60
Q

what is the best absorber of a gamma ray?

A

a thick sheet of lead

61
Q

what is the best absorber of beta radiation?

A

aluminium, copper or steel

62
Q

how many isotopes does iodine have?

63
Q

when is it decayed by alpha decay?

A

when the nuclei is too large (larger than lead)

64
Q

when is it decayed by beta decay?

A

when the nuclei has too many neutrons

65
Q

what happens to the mass number in alpha decay?

A

drops by 4

66
Q

what happens to the atomic number (proton number) in alpha decay?

A

drops by 2

67
Q

what happens to the mass number in beta decay?

A

stays the same

68
Q

what happens to the atomic number in beta decay?

A

increases by 1

69
Q

what is the atomic mass number of the emitted alpha particle?

70
Q

what is the number of protons in an alpha particle?

71
Q

what is the number of neutrons in an alpha particle?

72
Q

what is the atomic mass number emitted beta particle?

73
Q

what is meant by half life?

A

the time taken for half of the unstable nuclei to decay

74
Q

what does an unstable nuclei do to become stable?

A

emits radiation

75
Q

Can you predict radioactive decay? why?

A

No because it is random, spontaneous and unpredictable

76
Q

what is activity measured in?

A

becquerel (Bq)

77
Q

what is activity?

A

the rate at which a source of unstable nuclei decay

78
Q

what is contamination?

A

when an object/body contains a small amount of a radioactive isotope

79
Q

what is irradiation?

A

when an object or body is exposed to nuclear radiation

80
Q

when is it irradiation?

A

when it is alpha, beta, gamma radiation

81
Q

when is it contamination?

A

when it is an isotope or an element

82
Q

how to protect against contamination?

A

control the isotope
- wear gloves
- breathing apparatus

83
Q

how to protect against irradiation? (4)

A

block the radiation
- lead/ concrete shields
-badges to monitor the dose
- limit exposure time
- keep your distance

84
Q

how are alpha particles used for smoke detectors?

A

when smoke gets into the detectors the alpha particles are blocked —> so ionisation can no longer take place —> signal is sent to alarm

85
Q

how are beta particles used to make paper?

A

too much beta particles means the paper is too thin so sends message to computer

86
Q

how are gamma particles used in food production?

A

ionise DNA within bacteria and fungi –> stops them from reproducing (on food)

87
Q

what are 3 hazards of ionising radiation?

A
  1. can damage DNA
  2. kills cells and (3) destroys tissues
88
Q

what does contamination do?

A

transfers the source

89
Q

Irradiation is…

A

is emission from the source

90
Q

which has a higher level of risk contamination or irradiation?

A

contamination

91
Q

which lasts longer contamination or irradiation?

A

contamination
- irradiation is temporary

92
Q

n.d What did Rutherford come up with?

93
Q

n.d what did Bohr come up with in 1919?

94
Q

is beta radiation an electron?

A

It’s not actually an electron , it is a particle that is identical to an electron but comes from the nucleus.

95
Q

where does beta radiation (particle) come from?

A

the nucleus

96
Q

what is neutral radiation?

Physics (8 decks)

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