Radioactivity and particles Flashcards
(89 cards)
1
Q
What is the relative mass of a proton
A
1
2
Q
What is the relative mass of a neutron
A
1
3
Q
What is the relative mass of an electron
A
Negligible
4
Q
What is the relative charge of a proton
A
+1
5
Q
What is the relative charge of a neutron
A
0
6
Q
What is the relative charge of a electron
A
-1
7
Q
What is the mass number
A
The number of neutrons + protons in the nucleus of the atom
8
Q
What is the atomic number
A
The number of protons (equal to number of electrons)
9
Q
Where are the protons and neutrons in an atom
A
In the nucleus
10
Q
Where are the electrons in a atom
A
The shells of the atom orbiting the nucleus
11
Q
Define an ion
A
A charged atom. The atom is charged by gaining or losing electrons
12
Q
Define an isotope
A
A atom of the same element with the same number of protons but a different number of neutrons
13
Q
Define ionising radiation
A
Radiation that can ionise another atom (make it lose or gain an electron)
14
Q
What are alpha particles, beta particles and gamma rays
A
Ionising radiation that are emitted from an unstable nucleus in a random process
15
Q
What is the nature of alpha particles
A
2 protons and 2 neutrons, helium nucleus
16
Q
What is the relative charge of alpha particles
A
+2
17
Q
What is the range in air of alpha radiation
A
10cm
18
Q
What is the penetrating power of alpha radiation
A
Low
19
Q
What are the absorbers of alpha radiation
A
A thin piece of paper, human dead skin cells
20
Q
What is the ionising power of alpha particles
A
High
21
Q
Do alpha particles have deflection by electric and magnetic field
A
Yes because they have a charge
22
Q
What is the nature of beta particles
A
Fast moving electron from the nucleus
23
Q
What is the relative charge of beta particles
A
-1
24
Q
What is the range in air of beta particles
A
1metre
25
What is the penetrating power of beta particles
Medium
26
What is an absorber of beta particles
Aluminium-a few mm
27
What is the ionising power of beta particles
Medium
28
Do beta particles have deflection by electric and magnetic field
Yes because they have a charge
29
What is the nature of a gamma ray
Electromagnetic wave
30
What is the relative charge of a gamma ray
0
31
What is the range in air of gamma rays
Infinite
32
What is the penetrating power of gamma rays
High
33
What is an absorber of gamma rays
Thick lead, thick concrete
34
What is the ionising power of gamma rays
Low
35
Do gamma rays have deflection by electric and magnetic field
No because it doesn’t have a charge
36
Why does alpha have the lowest penetrating power
Alpha has a relative charge of 2+ which is higher than beta or gamma. This means alpha has the highest ionising power meaning it is more likely to ionise. by having the highest mass it is more likely to be absorbed hence it has the lowest penetrating power
37
Why does beta have this nature
A neutron decays into a proton and electron. The electron is then forced out of the nucleus
38
What is the nuclear notation of an alpha particle
4 alpha
2
39
What is an example of a nucleus decaying and emitting alpha radiation
233 U -> 4 a + 229 X
92 2 90
40
Does the nuclear notation of alpha change
No it is always fixed
41
What is the nuclear notation of beta radiation
0 B
-1
42
Does the nuclear notation of beta change
No it is always fixed
43
What is an example of a nucleus decaying and emitting beta radiation
90 Sr -> 0 B + 90 X
38 -1 39
44
What is the nucleus notation of a gamma ray
0 gamma
0
45
What happens when a nucleus decays and emits a gamma wave
There is no change to the mass or atomic number
46
Why does the mass and atomic number remain the same when gamma radiation is emitted
Gamma rays are a type of electromagnetic radiation meaning gamma only transfers energy out of the decayed nucleus
47
What is one way ionising radiation can be detected
Using a Geiger Muller tube and counter. The tube detects the radiation and the counter records how many times the tube has detected radiation
48
What is a second way ionising radiation can be detected
By using photographic plates. When the radiation reacts with the plates the plate will change colour. If there is metal in the way it will not change colour as the radiation is absorbed
49
What are five sources of background radiation
Radon gas, buildings and the ground, artificial sources, cosmic rays, food and drink
50
How does radon gas emit background radiation
Radon gas is emitted out of the ground accounting for 50% of background radiation
51
How do buildings and the ground contribute to background radiation
Some rocks can be radioactive
52
How do food and drinks contribute to background radiation
Some food such as Brazil nuts, bananas and shellfish emit radiation
53
How do cosmic rays contribute to background radiation
Cosmic rays are streams of radiation from space gamma rays which are emitted from a star
54
How do artificial sources contribute to background radiation
Human use means new technologies have been created. Nuclear power and weapons testing and medical- diagnosing and cancer treatments
55
What happens to the activity of a radioactive source over time
It decreases
56
What is the activity of a radioactive source measured in
Becquerel
57
Define half life
Half life is the average time taken from half of the unstable nuclei to decay
58
How do you use a graph to estimate the half life of a sample
Half the amount of radiation counted per minute then draw a line across and down to the time taken
59
Why is the half life different for different nuclei
Different isotopes have a different number of neutrons which affects their nuclear stability and half lifes
60
A isotope initially consists of 1200 unstable nuclei. If it has a half life of two minutes how long until only 150 nuclei remain
After 2 minutes 600 nuclei will be stable
0=1200
2=600
4=300
6=150
6 minutes
61
How do smoke detectors use radiation
-alpha particles are used as they have a high ionising power but a low penetration and range meaning they are less dangerous and can be absorbed by smoke
-when alpha radiation is detected nothing happens but if smoke is presents smoke absorbs the alpha and none reaches the detector so alarm sounds
62
Why is it important that alpha radiation has a long half life ion a smoke alarm
It makes the smoke detector more reliable so it last for a long time
63
How is beta radiation used in the ,manufacture of aluminium foil
It controls the foils thickness. If it is too thick it absorbs more beta particles meaning the detector receives less beta particles and then send a signal to the rollers to apply more pressure. If the foil is too thin it absorbs to many particles so the signal is sent and the force is decreased in the rollers
64
Why is a beta source used in the production of aluminium foil
As aluminium absorbs beta. Alpha will always be absorbed. Gamma rays has a higher penetrating power and is not absorbed by aluminium
65
How do radioactive tracers use gamma radiation to find leaks
A gamma emitting radioactive isotope is added to water in the pipe. Where there is a leak, contaminated water seeps into the ground causing a build up of gamma emissions
66
Why is gamma radiation use in radioactive tracers
They have a high penetrating power and infinite range in air so they can go through pipes but alpha and beta can’t meaning they aren’t traceable
67
How do medical tracers work
Radioactive material is injected into the body. It is irradiated though the body and with a gamma camera problems can be found
68
Why is it important to use a radioactive isotope with a short half life when using medical tracers
So it can decay quickly to reduce the risk
69
Why is gamma or beta radiation used in medical tracers
Both can travel through skin and tissues but alpha can’t so it wont be detected on a gamma camera
70
How do gamma medical treatments work
Radioactive cobalt projects high energy beams sending an intense dose of radiation from different directions
71
Why is a holey helmet used during gamma treatments
To make sure the rays only go to the target area and no where else
72
Define contamination
Occurs when the radioactive source is on or inside the object
73
Define irradiation
Occurs when an object us exposed to a source of radiation outside the object
74
What are the dangers of ionising radiation
Radiation can burn skin or cause cancer
75
What is nuclear fission reactions a source of
Energy released as kinetic energy of the daughter nuclei r and neutrons. These then collide transferring their kinetic energy to a thermal store
76
Describe nuclear fission
If a nucleus is very large and unstable then it can undergo fission. This is where a slow moving neutron is absorbed by the larger nucleus eg uranium 235 creating uranium 236, then the nucleus splits into two daughter nuclei and two or three neutrons
77
How is a chain reaction cause by nuclear fission
The neutrons are the product of the decay. Each neutron emitted can go on to be absorbed by uranium and cause more fission
78
Define a chain reaction
The products from one reaction go to become the reactants of the next reaction
79
What is a runaway reaction
Where more and more product is created causing more and more reactions per second. It also produces more and more energy envy second which can be very dangerous
80
What is the role of the control rods in a nuclear power station
They go between the fuel rods controlling the reaction by absorbing neutrons. They are made from boron
81
What’s is the role of the moderator in a nuclear power station
Slows down the neutrons which keeps the reaction happening. Uses graphite of water
82
Why is water used in moderators
It is a safety feature so if the water gets too hot and boils it turns into steam
83
What is the role of shielding in a nuclear power station
Thick concrete is used to completely incase the reactor. This means it absorbs alpha and beta radiation and reduces gamma rays to a safe level
84
What is the difference between nuclear fission and fusion
In nuclear fission a large nucleus splits into smaller nuclei and neutrons. In nuclear fusion two small nuclei fuse together to make a bigger nucleus
85
Describe the process of fusion
The sun is made up of plasma meaning all the atoms have been ionised. It is so hot, meaning the nuclei have lots of energy to move quickly, and under very high pressure, meaning the nuclei are close together, in the sun that the nuclei collide with each other and combine
86
Where does fusion occur
In stars such as the sun
87
What equipment is needed to measure the penetration powers of different radiation
-3 radioactive sources emitting alpha beta and gamma
-absorbing materials:paper, 1-2cm thick aluminium, thick lead
-metre ruler
-long handled tongs and gloves
-Geiger muller tube and counter
-stop clock
88
What is the method to measure the penetrating powers of different radioactive sources
-measure the background count of radiation using the GM tube and counter for 30 seconds
-place a radioactive source 5cm away from the GM tube
-record the counts detected from the source with no absorbing materials for 30 seconds
-place a piece of paper between the GM tube and material and record for 30 seconds
-repeat with two other absorbing materials
-relearn with two other radiation sources
89
What are the safety procedures when using radioactive sources
-stand at least 2 metres away if still growing
-dont come in room if pregnant
-put warning signs up on door
-dont touch materials use long handled tongs
-dont point sources as anyone
-remove sources when finished
