3.2.1: Particles And Radiation Flashcards
(113 cards)
1
Q
Describe the structure of an atom
A
A positively charged nucleus composed of both protons and neutrons surrounded by negatively charged electrons which orbit in shells
2
Q
What is a nucleon?
A
A proton or neutron in a nucleus
3
Q
What is the charge of a proton?
A
1.6 x 10^-19
4
Q
What is the mass of a proton?
A
1.67 x 10^-27
5
Q
What is the charge of a neutron?
A
0
6
Q
What is the mass of a neutron?
A
1.67 x 10^-27
7
Q
What is the charge of an electron?
A
-1.6 x 10^-19
8
Q
What is the mass of an electron?
A
9.11 x 10^-31 kg
9
Q
What are isotopes?
A
Atoms with the same number of protons and different number of neutrons
10
Q
What is the nucleon number (A)?
A
Number of protons and neutrons in the nucleus
11
Q
What is the proton number (Z)?
A
Number of protons
12
Q
What is the relative charge of a proton?
A
+1
13
Q
What is the relative charge of a neutron?
A
0
14
Q
What is the relative charge of an electron?
A
-1
15
Q
What is the relative mass of a proton?
A
1
16
Q
What is the relative mass of a neutron?
A
+1
17
Q
What is the relative mass of an electron?
A
0.0005
18
Q
What is the formula for specific charge?
A
Specific charge = charge/mass
19
Q
What keeps protons and neutrons in a nucleus together?
A
The strong nuclear force
20
Q
Why are some nuclei unstable?
A
They have too many protons, neutrons or both causing the strong nuclear force to not be strong enough
21
Q
What happens to the strong nuclear force at distances less than 0.5fm?
A
The strong nuclear force is repulsive
22
Q
What happens to the strong nuclear force at distances above 0.5fm?
A
The force is attractive
23
Q
What distance is the strong nuclear force most attractive at?
A
1fm
24
Q
What happens at distances above 3fm?
A
The strong nuclear force has negligible effect
25
What does the strong nuclear force do within the atomic nucleus?
Hold protons and neutrons together by counteracting the electrostatic force of repulsion between the protons
26
Why do unstable isotopes undergo nuclear decay?
To emit particles to become more stable
27
What are the main types of nuclear decay?
Alpha - occurs in large nuclei with too many neutrons and protons
Beta minus - occurs in neutron rich nuclei
28
What type of decay is highly ionising but has a range of only a few cm in air?
Alpha
29
What changes occur to the nucleus during alpha decay?
- Proton number decreases by 2
- Nucleon number decreases by 4
30
What are the properties of beta minus particles?
High speed electrons with a range of several m in air
31
What happens during beta minus decay?
One of the neutrons decays into a proton and emits a beta-minus particle and antineutrino
32
What changes occur to the nucleus during beta minus decay?
- Proton number increases by 1
- Nucleon number stays the same
33
What is an antiparticle?
For each particle there is an antiparticle with the same rest energy and mass but all other properties are the opposite of its respective particle.
34
What is the mass of a positron?
Same as electron
35
What is the rest energy of an electron?
0.511 MeV
36
What is the rest energy of a positron?
0.511 MeV
37
What is the rest energy of an electron neutrino?
0
38
What is the rest energy of an electron antineutrino?
0
39
What is the charge of a positron?
1.6 x 10^-19
40
What is the charge of an electron neutrino?
0
41
What is the charge of an electron antineutrino?
0
42
What are photons?
- Packets of EM radiation
- With energy proportional to their frequency or inversely proportional to their wavelength
43
How does electromagnetic radiation travel?
In packets called photons which transfer energy and have no mass
44
What is the formula for energy of a photon?
E = hf
E - energy
H - Planck's constant
F - frequency
45
What is the value of Planck's constant?
6.63 x 10^-34 Js
46
What is annihilation?
- When a particle and its antiparticle collide,
- As a result their masses are converted into energy.
- This energy along with kinetic energy is released in the form of 2 photons moving in opposite directions in order to conserve momentum
47
What can a PET scanner be used for?
3D images of the inside of a body to be taken, making medical diagnoses easier
48
How does a PET scan work?
- Introducing positron-emitting radioisotopes into the patient,
- As positrons are released they annihilate with the electrons in the patient's system.
- This emits gamma photons which can be detected easily
49
What is the equation for photon energy in terms of wavelength?
hc/λ
H - Planck's constant
C - speed of light
λ - wavelength
50
What is pair production?
When a photon is converted into an equal amount of matter and antimatter
51
When can pair production occur?
When the photon has an energy greater than the total rest energy of both particles.
52
What are the four fundamental forces?
Gravity, electromagnetic, strong nuclear, weak nuclear
53
What are exchange particles?
Virtual particles which are responsible for how forces act between two particles
54
What is the exchange particle of weak nuclear force?
The W boson (W+ or W-).
55
What is the exchange particle of electromagnetism?
Virtual photon
56
What is the range of a virtual photon?
Infinite
57
What is the range of W boson in metres?
10^-18
58
What does the strong nuclear force act on?
Hadrons
59
What does the weak nuclear force act on?
All particles
60
What does electromagnetism work on?
Charged particles
61
What does gravity work on?
Particles with mass
62
What is the weak nuclear force responsible for?
- Beta decay,
- Electron capture
- Electron-proton collisions
63
What is the equation for electron capture and electron-proton collision?
p + e- --> n + Ve
64
What is the beta plus decay equation?
proton -> neutron + positron + neutrino
65
What is the beta minus decay equation?
neutron -> proton + electron + antineutrino
66
What are leptons?
They are fundamental particles and are not affected by the strong nuclear force as they cannot be broken down any further
67
What are hadrons?
These can feel the strong nuclear force. They are not fundamental, they are made up of quarks
68
What are the 3 types of hadrons?
Baryons, antibaryons and mesons
69
What are baryons?
Made up of 3 quarks
70
What are antibaryons?
Made up of 3 antiquarks
71
What are mesons?
Made up of a quark and an antiquark
72
How to recognise if a particle is a baryon?
The baryon number is 1
73
How to recognise if a particle is an antibaryon?
The baryon number should be -1
74
What is the only stable baryon?
Proton, all other baryons will decay into a proton
75
What are the two types of lepton numbers?
Electron lepton number and muon lepton number
76
What is a muon?
A particle that decays into an electron
77
What are strange particles?
Particles that are produced through the strong interaction and decay through the weak interaction
78
What is an example of a strange particle?
Kaon which decays into pion
79
What is the exchange particle of the strong nuclear force?
Pion
80
What does strangeness show?
That strange particles are created in pairs as strangeness must be conserved in weak interactions
81
How much can strangeness change by?
0, +1, -1
82
How must we investigate particle physics?
Particle accelerators must be built, however they are expensive, so scientific investigations rely on the collaboration of scientists internationally
83
What are quarks?
Fundamental particles that make up hadrons
84
What are the 3 types of quarks?
Up, down, strange
85
What is the charge of the up quark?
+2/3 e ("e" stands for the charge of an electron)
86
What is the charge of the down quark?
-1/3 e
87
What is the charge of the strange quark?
-1/3 e
88
What is the baryon number of the quarks?
+1/3
89
What is the strangeness of the up quark?
0
90
What is the strangeness of the down quark?
0
91
What is the strangeness of the strange quark?
-1
92
How to find out the quark combination of an antibaryon if you know the quark combination of the baryon?
Change the quarks into their antiquarks, this can also be applied for mesons
93
What is the quark combination for a proton?
uud
94
What is the quark combination for a neutron?
udd
95
What is the quark combination for π°?
uˉu or dˉd
96
What is the quark combination for π+?
uˉd
97
What is the quark combination for π-?
ˉu d
98
What is the strangeness of all pions?
0
99
What is the charge of π°?
0
100
What is the charge of π+?
1
101
What is the charge of π-?
-1
102
What is the quark combination for k°?
Dˉs or sˉd
103
What is the charge of k°?
0
104
What is the strangeness of k°?
+1
105
What is the quark combination for k+?
uˉs
106
What is the charge for k+?
1
107
What is the strangeness of k+?
1
108
What is the quark combination of k-?
ˉu s
109
What is the charge of k-?
-1
110
What is the strangeness of k-?
-1
111
What is the equation for the decay of a neutron into a proton?
Neutron —> proton + electron + antineutrino
112
What properties must always be conserved in particle interactions?
Energy and momentum
Charge
Baryon number
Electron lepton number
Muon lepton number
113
When must strangeness be conserved?
Strong interactions
