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PHYSICS IGCSE > radioactivity > Flashcards

radioactivity Flashcards

1
Q

what is in the nucleus of an atom

A

protons and neutrons

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2
Q

the mass number is the

A

biggest number

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3
Q

atomic number is

A

the number which tells you how many protons there are

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4
Q

if an atom loses electrons it becomes

A

ionised

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5
Q

the number of protons determines

A

which element an atom is

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6
Q

is the atomic number always the same for an atom

A

yes

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7
Q

the mass number tells you

A

the number of protons and neutrons in the atom

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8
Q

an isotope is

A

an element with the same number of protons but different number of neutrons

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9
Q

can an element have more than 1 isotope

A

yes

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10
Q

some atomic nuclei can be unstable and

A

radioactive

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11
Q

why are some nuclei unstable and radioactive

A

because of an imbalance of protons or neutrons in the nucleus

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12
Q

how can unstable nuclei become more stable

A

by emiting radiation

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13
Q

name of the process of radioactivity to make a nuclei more stable

A

radioactive decay

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14
Q

radiation can be in the form of what (2)

A

high-energy particle or wave

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15
Q

When an unstable nucleus decays, it emits

A

radiation

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16
Q

The different types of radiation that can be emitted are:

A

Alpha (α) particles

Beta (β-) particles

Gamma (γ) radiation

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17
Q

are these changes spontaneous and random

A

yes

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18
Q

symbol for alpha

A

α

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19
Q

An alpha particle is the same as a

A

helium nucleus

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20
Q

why is an alpha particle is the same as a helium nucleus

A

because it consists of two neutrons and two protons

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21
Q

symbol for beta

A

β−

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22
Q

Beta particles are

A

high-energy electrons

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23
Q

when are beta particles produced

A

during beta minus decay, when a proton in the nucleus is converted into a neutron

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24
Q

symbol for gamma

A

γ

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25
Q

gamma rays are

A

electromagnetic waves

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26
Q

gamma rays have the ___ energy of the different types of electromagnetic waves

A

highest

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27
Q

Alpha (α), beta (β) and gamma (γ) radiation can be identified by their: (3)

A

Nature (what type of particle or radiation they are)

Ionising ability (how easily they ionise other atoms)

Penetrating power (how far can they travel before they are stopped completely)

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28
Q

alpha is stopped by

A

paper

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29
Q

ionising ability of alpha

A

high

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30
Q

beta particles are what

A

high energy electrons

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31
Q

beta is stopped by

A

aluminium foil or 10cm of air

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32
Q

ionising ability of beta is

A

moderate

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33
Q

gamma is what

A

an electromagnetic wave

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34
Q

gamma is stopped by

A

nothing

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35
Q

ionising ability of gamma

A

low

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36
Q

PRACTICAL- investigating penetrating power for different types of ionisation

A
  • need a geiger-muller tube connected to a geiger counter
  • without any sources present, measure background radiation over a period of one minute
  • place a radioactive source a fixed distance away from the tube and take the reading of the count rate for 1 minute
  • take some paper, alumunium and lead
  • one at a time, place the absorbers between the source and the tube and take another reading of count rate for 1 minute
  • repeat with other radioactive sources and depending on what they pass through, check if its gamma or beta or alpha
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37
Q

alpha particles have a mass number of _ and an atomic number of _

A

4
2

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38
Q

beta minus particles have a mass number of _ and an atomic number of _

A

0
-1

39
Q

gamma has a mass and atomic number of

A

0

40
Q

in alpha decay, what do you do

A

-4 and -2

41
Q

in beta decay what do you do

A

add 1 to the bottom

42
Q

how is ionising radiation detected

A
  • geiger muller tube and photographic film
43
Q

Photographic films detect radiation by becoming ____ when it absorbs radiation

A

darker

44
Q

what is backround radiation

A

The radiation that exists around us all the time

45
Q

the natural backround radiation we have comes from (2)

A

space and earth

46
Q

sources of backround radiation

A

radon gas (50%)
rocks and building materials (15%)
medical x-rays (13%)
food (11%)

47
Q

2 types of backround radiation

A

Natural sources

Artificial (man-made) sources

48
Q

radon gas comes from

A

Airborne radon gas comes from rocks in the ground, as well as building materials e.g. stone and brick

49
Q

how is radon gas detected

A

Radon gas is tasteless, colourless and odourless so it can only be detected using a Geiger counter

50
Q

cosmic rays come from

A

space (sun)

51
Q

biological material and carbon 14

A

All organic matter contains a tiny amount of carbon-14

52
Q

Radioactive material in food and drink

A

Naturally occurring radioactive elements can get into food and water since they are in contact with rocks and soil containing these elements

53
Q

natural sources of backround radiation (4)

A

randon gas from rocks and buildings

cosmic rays from space

carbon 14 in biological material

radioactive material in food and drinks

54
Q

Artificial Sources of Background Radiation (4)

A

nuclear medicine

nuclear waste

Nuclear fallout from nuclear weapons

Nuclear accidents

55
Q

are natural backround waste usually a cause for concern

A

NO

56
Q

nuclear waste in backround radiation

A

itself does not contribute much to background radiation, it can be dangerous for the people handling it

57
Q

Nuclear medicine in backround radiation

A

In medical settings, nuclear radiation is utilised all the time

58
Q

Nuclear fallout from nuclear weapons - backround radiation

A

Fallout is the residue radioactive material that is thrown into the air after a nuclear explosion, such as the bomb that exploded at Hiroshima

59
Q

nuclear accidents backround radiation

A

Nuclear accidents, such as the incident at Chornobyl, contribute a large dose of radiation to the environment

While these accidents are now extremely rare, they can be catastrophic and render areas devastated for centuries

60
Q

the activity of a radioactive source ____ over a period of time and is measured in ____

A

decreases

bequerels

61
Q

The activity of a radioactive source decreases with time because

A

each decay event reduces the overall number of radioactive particles in the source

62
Q

Activity is measured in

A

becquerels

63
Q

Radioactive decay is a ___ process

A

random

64
Q

half life is

A

the time taken for half of the radioactive nuclei in a sample to decay

65
Q

half life for a given isotope is the same or different depending on size ?

A

same

66
Q

does the line in a half life graph touch the x axis

A

no it gets closer but never touches it

67
Q

alpha radiation is used in

A

smoke detectors

68
Q

how do alpha particles work in a smoke detector

A

when there is no smoke, the alpha ionises the air forming charged particles which complete the circuit

when there is fire, smoke is produced which breaks the circuit as alpha particles are absorbed and air is no longer ionised, this causes the alarm to ring

69
Q

use of beta radiation

A

to monitor the thickness of sheets of material

its measured using a geiger- muller counter

70
Q

use of gamma radiation

A

destroys microorganisms on food and extends the usable lifetime of food

71
Q

second use of gamma (medical)

A

to sterilise medical equipment

72
Q

in beta radiation when monitoring the thickness of materials, what happens if its too thick

A

the reading becomes very low

73
Q

in beta radiation when monitoring the thickness of materials, what happens if its too thin

A

the reading is very high

74
Q

why do count rates change in a geigger muller counter ( beta)

A

thicker materials (lead) absorb more radiation while thinner ones absorb less

75
Q

what slows gamma down

A

lead

76
Q

what is contamination

A

the accidental or unwanted transfer of a radioactive substance onto or into a material

77
Q

A substance is only radioactive if it contains

A

a source of ionising radiation

78
Q

contamination happens when

A

a radioactive isotope gets onto a material where it should not be, and as a result the small amounts of the isotope in the contaminated areas will emit radiation and the material becomes radioactive

79
Q

what is irridation

A

The process of exposing a material to ionising radiation

80
Q

does irradiating a substance make it radioactive

A

NO

81
Q

what can irradiating a substance cause

A

cells to be killed

82
Q

contamination is usually an

A

accident

83
Q

irradiation is usually

A

on purpose

84
Q

example of irradiation

A

sterilisation of food or medical equipment

85
Q

when is medical equipment irradiated

A

before being used in order to kill any micro-organisms on it before surgery

86
Q

when is food irradiated

A

d to kill any micro-organisms within it to make it last longer

87
Q

radiation can cause harm in two ways, what are they

A

irradiation and contamination

88
Q

how is ionising radiation harmful to living things

A
  • kills and ionises living cells ( tissue cells)
  • mutations of cells
89
Q

tissue damage through radiation usually happens by

A

high energy EM radiation (like gamma rays)

90
Q

what happens in mutation of cells by radiation

A
  • atoms in the DNA are ionised
  • DNA can mutate while repairing
  • if they replicate then it means that they form a tumour
91
Q

precautions that can be taken to reduce radiation waste (3)

A
  • increase distance from source (which reduces intensity and chance of contamination)
  • reduce time spent near the source (decreases amount of radiation recieved)
  • shielding (reduces amount of radiation which reaches the user)
92
Q

by-products of nuclear power production often have __ half lives

Meaning …

A

LONG

they could remain a risk for thousands of years

93
Q

what precaution is taken to get rid of by products of nuclear power production and why

A

storing them underground as it reduces the risk because not even gamma can pass through large amounts of earth and rock

PHYSICS IGCSE (19 decks)

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