P3.3 Production, uses and risks of ionising radiation from radioactive sources Flashcards
1
Q
What is tritium?
A
A radioactive form of hydrogen
2
Q
What does an atom consist of?
A
Protons, neutrons and electrons
3
Q
What are nucleons?
A
Protons and neutrons
4
Q
What is the atomic number?
A
The number of protons in an atom
5
Q
What is the mass number?
A
The number of protons or neutrons in total
6
Q
What is beta decay?
A
The emission of electrons or positrons when a radioactive material decays
7
Q
What are beta particles?
A
Electrons and positrons
8
Q
What is a positron?
A
The anti-particle of an electron, it has the same mass but opposite charge.
9
Q
What are two types of beta (β) decay?
A
- beta minus decay (β-)
- beta plus decay (β+)
10
Q
What happens during β- decay?
A
- A neutron becomes a proton
- an electron (beta particle) is emitted
11
Q
What can beta minus decay penetrate?
A
Paper
12
Q
What does ionising mean?
A
Capable of turning atoms into ions (charged particles)
13
Q
What happens to an ion that loses an electron?
A
It becomes a positive ion
14
Q
What happens to an ion that gains an electron?
A
It becomes a negative ion
15
Q
What happens to the atomic and mass numbers after β- decay?
A
- the atomic number decreases by one
- the mass number is unaffected
16
Q
What happens during β+ decay?
A
- a proton becomes a neutron
- a positron is emitted
17
Q
What happens to the atomic and mass numbers after β+ decay?
A
- decreases the atomic number by one
- leaves the mass number unaffected
18
Q
What can’t beta particles penetrate?
A
Thin sheets of metal
19
Q
What is the charge of a positron?
A
+1
20
Q
What are the three types of radioactive emission called?
A
- alpha (α)
- beta (β)
- gamma (γ)
21
Q
What are alpha and beta emissions made up of?
A
Particles
22
Q
What are gamma emissions?
A
Waves
23
Q
What is an alpha particle made up of?
A
Two protons and two neutrons
24
Q
What is the most penetrating type of radiation?
A
Gamma
25
What is the most ionising type of radiation?
Alpha
26
What is the least penetrating type of radiation?
Alpha
27
What is the least ionising type of radiation?
Gamma
28
Why are alpha particles the most ionising?
They are very big and so are easily capable of dislodging electrons from any atoms they collide with
29
Why are alpha particles the least penetrating?
Their big size means they have more collisions which means that they lose energy quickly and so have a limited range
30
What happens to the atomic number and mass after alpha decay?
The atomic number decreases by two and the mass number decreases by four
31
What happens during alpha decay?
The nucleus emits an alpha particle
32
What happens during gamma decay?
The nucleus emits a gamma ray
33
What absorbs gamma rays?
A few centimetres of metal
34
Why does an unstable nucleus undergo decay?
To become stable
35
What happens to the atomic and mass number after gamma radiation?
Nothing
36
Why does gamma radiation cause no change in atomic and mass number?
Because it has no mass
37
How does gamma decay make radioactive materials stable?
When gamma rays are emitted the nucleus loses energy
38
What is neutron radiation equal to in terms of penetration?
Gamma radiation
39
What is neutron radiation?
The emission of a neutron during radioactive decay
40
Why aren't neutrons ionising?
They have no charge
41
What must be the same on each side of a nuclear reaction?
The atomic and total mass number
42
What type of nucleus is an alpha particle?
A helium nucleus
43
What is an alpha particle written as in a nuclear reaction?
4
He
2
44
What is an electron written as in a nuclear reaction?
0
e
-1
45
What is a positron written as in a nuclear reaction?
0
e
+1
46
What is a gamma ray written as in a nuclear reaction?
0
γ
0
47
What do all isotopes of an element have in common?
The same number of protons
48
What causes there to be different isotopes within an element?
Different numbers of neutrons
49
What does it mean when an isotope is stable?
It will keep the same number of protons and neutrons indefinitely
50
What happens to unstable isotopes?
They decay
51
What does a stability curve graph show?
How likely it is an isotope will decay and what kind of decay it will undergo
52
Where are lighter elements found on the stability curve graph?
The bottom left corner
53
Where are heavier elements found on the stability curve graph?
Towards the top right
54
What does the straight line N=Z show on a stability curve graph?
Where elements will appear if they have the same number of protons as neutrons
55
What does a line called the N-Z curve show on a stability curve graph?
Stable isotopes
56
What is another name for the N-Z curve?
A stability curve
57
Where does the stability curve stop at?
Z=82
58
Why does the stability curve stop at Z=82?
Above this all isotopes are unstable
59
What kind of decay do isotopes above the N-Z curve undergo?
β- decay
60
Why do isotopes above the N-Z curve undergo β- decay?
They have too many neutrons to be stable
61
Why are isotopes below the N-Z curve likely to undergo β+ decay?
They have too many protons
62
What two types of radiation are isotopes below the N-Z curve likely to undergo?
β+ and α radiation
63
What state are radioactive isotopes in?
Unstable
64
Where are the isotopes of the heaviest elements likely to be found on the N-Z stability graph?
Towards the top right when Z ≥ 82
65
What type of decay do many isotopes of the heaviest elements usually undergo?
Alpha
66
What are protons and neutrons made up of?
Quarks
67
What type of particles are protons and neutrons?
Hadrons
68
What mass does an up quark have?
1/3
69
What mass does a down quark have?
1/3
70
What charge does an up quark have?
+2/3
71
What charge does a down quark have?
-1/3
72
What quarks does a proton consist of?
Two up quarks and one down quark (udu)
73
What quarks does a neutron consist of?
One up quark and two down quarks (dud)
74
How many quarks does one neutron or proton contain?
Three
75
Why can protons change into a neutron and vice versa?
Because quarks can change from one type to another, e.g. down to up or up to down
76
What type of decay does an element undergo when an up quark changes into a down quark?
β+
77
What type of decay does an element undergo when a down quark changes into an up quark?
β-
78
How can radiation cause cancer?
It damages DNA within living cells which can cause mutations which can lead to cancer
79
What does dosage mean in radiation treatment?
The total amount of radiation absorbed by the patient
80
What two factors does the likelihood of getting burns from radiation depend on?
- the amount of exposure
| - the type of source
81
What type of radiation burns look similar to sunburn?
Beta
82
How far do beta burns reach?
The surface of the skin
83
What type of radiation causes the deepest burns?
Gamma
84
Why does gamma radiation cause the deepest burns?
It is the most penetrating
85
How do medical staff minimise their exposure to radioactive sources?
- increasing their distance from the source
- shielding
- containment
- minimising the amount of time spent in its presence
86
How is the amount of radiation medical staff are exposed to monitored?
Using a dosimeter
87
What are two reasons why patients might be exposed to radiation?
Diagnosis and treatment
88
What is radiotherapy used for?
Treating cancers and palliative care
89
What type of radioactive source is used for internal radiotherapy?
A beta emitter
90
What type of radioactive source is used for external radiotherapy?
A gamma source or high frequency X-rays
91
What is palliative care?
A medical intervention that doesn't cure a condition but may reduce pain and other symptoms
92
How can radiotherapy be used in palliative care?
It can shrink tumours
93
What is a tracer?
A substance which is usually used by the body which is made using atoms from radioactive isotopes
94
Why are some tracers used directly instead of being incorporated into larger molecules?
They are already directly absorbed by some parts of the body
95
How does a tracer diagnose cancer?
They are more concentrated in areas where there are diseased tissues or tumours, which show up in a PET scan
96
Why does a tracer need to have a short half-life?
So that other parts of the body are affected as little as possible
97
What locates the tracer?
a PET scanner
98
What tracer does the brain absorb?
Technetium-99
99
What tracer does the thyroid gland absorb?
Iodine-123
100
What tracers do the lungs absorb?
Nitrogen-13 and oxygen-15
101
What tracer do the bones absorb?
Indium-111
102
What happens when a positron collides with an electron?
Total annihilation, two gamma rays are released in opposite directions
103
How does a PET scan detect tracers?
It emits electrons which collide with the positrons emitted from the tracers. This releases two gamma rays which are released in opposite directions and are detected by the PET camera. The computer can then use triangulation to see where the rays came from and so can see where the highest concentration of tracer and therefore diseased cells or tumours are
104
Why do all medical radioactive techniques carry a risk?
They increase the amount of exposure to patients
105
What is the speed of a gamma ray?
The speed of light
