07 Radioactivity And Particles Flashcards

(68 cards)

1
Q

Proton relative charge, relative mass and location

A

Relative charge = +1
Relative mass = 1
Location = nucleus

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2
Q

Neutron relative charge, relative mass and location

A

Relative charge = 0
Relative mass = 1
Location = nucleus

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3
Q

Electron relative charge, relative mass and location

A

Relative charge = -1
Relative mass = 1/1835
Location = shells around nucleus

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4
Q

Atomic number

A

Small number
- number of protons

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5
Q

Mass number

A

Large number
- protons + neutrons

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6
Q

Number of neutrons =

A

Mass number - atomic number

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7
Q

Isotope

A

Elements with same number of protons but different number of neutrons
- so it has different mass number

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8
Q

What happens when a nucleus is unstable

A
  • it tries to become more stable by ejecting mass (beta/alpha) or energy (gamma)
  • the atoms are radioactive
  • process of ejecting is called decay
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9
Q

Decay is

A

Random

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10
Q

Alpha radiation

A

Helium nucleus emitted from nucleus
- 2 protons 2 neutrons

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11
Q

Beta radiation

A

Electron emitted from nucleus

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12
Q

Gamma radiation

A

High energy electromagnetic wave

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13
Q

Alpha ionising and penetration

A
  • very ionising
  • low penetration (stopped by paper)
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14
Q

Beta ionising and penetration

A
  • moderate ionisation
  • moderate penetration (stopped by aluminium)
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15
Q

Gamma ionising and penetration

A
  • not very ionising
  • very penetrating (stopped by lead)
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16
Q

Practical: investigate penetration powers of different types of radiation using radioactive sources

A
  • measure background count for 2 mins using Geiger-Muller (GM) tube and stopwatch —> with no radioactive sources present
  • set up source 2cm away from GM tube
  • record counts detected from source with no absorbing materials for 5 mins
  • place paper between ionising radiation source and GM tube and record counts detected for 2 mins
  • repeat with aluminium and lead and record counts
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17
Q

Why do you measure count for at least two minutes

A

To collect avg value since decay of unstable atoms is RANDOM

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18
Q

Alpha effect on mass/atomic number

A

4
2

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19
Q

Beta effect on mass/atomic number

A

0
-1

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20
Q

Gamma effect on mass/atomic number

A

0
0

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21
Q

Neutron effect on mass/atomic number

A

1
0

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22
Q

How does GM tube detect ionising radiation

A
  • detects when gas in chamber is ionised by radiation
  • every beep is one incidence on radiant (could be gamma/beta/alpha)
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23
Q

How does photographic film detect ionising radiation

A

When radiation comes into contact with photographic film it DARKENS
- shows presence of radiation

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24
Q

Origins of background radiation

A

Food and drink
Nuclear power
Medical
Radon gas
Cosmic rays

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25
Food and drink origin
Food and drink: radioactive isotopes decay over time
26
Nuclear power origin
Nuclear power: from power stations/bombs
27
Medical origin
Medical: x-rays/gamma ray scans/sterilisation/ cancer treatments
28
Radon gas
Radon gas: produced by rocks contains small amounts of uranium
29
Cosmic rays origin
Cosmic rays: radiation from space which is produced in stars
30
Activity of a sample of radioactive isotopes is measured of
How many radioactive decays happen over a period of time
31
What is activity of radioactive isotopes measured in
Becquerels (Bq)
32
Activist of a radioactive source ___ over time
Decreases
33
Half life
Time taken for half of undecayed nuclei to decay
34
Half life =
Time taken for activity to half its original value
35
Large samples of SAME radioactive substance have
Same half life
36
How to find number of undecayed nuclei in sample
State start number Go forward half life (divide by 2) and days stated Repeat until target time passed
37
Age os isotope
Total number in current sample Go back half life (x2 sample size) Repeat until all of sample is radioactive isotope
38
Smoke detector using radioactivity
- source gives off alpha particles which ionises air particles - air particles carry current across gas - when theres smoke the smoke absorbs ions created by source - alarm sounds when current falls/drops
39
Use of radioactivity in irradiating food/sterilising equipment
- ionising radiation kills small cells like bacteria In food gamma rays are used to kill bacteria —> last longer and is safe to eat In medicine gamma rays kills bacteria on plastic equipment —> sterile and safe to use
40
Use of radioactivity in gauging thickness
- beta radiation fired through paper/plastic sheets - amount of radiation passed through is sent to computer Too much radiation —> paper too thin —> computer tells rollers to move apart
41
Uses of radioactivity in tracing
Radioactive sources (gamma) added to water supplies to detect leaks Where water is leaking —> more water —> more radiation - detected above ground to find leaks without digging
42
Uses of radioactivity in treatment/diagnosis of cancer
- consume/inject gamma emitter —> passes through body and an external detector than pictures where the tracer has collected in body - reveals tumours - gamma is detected since it can pass through skin and tissues - ionising radiation used on tumour kills cancel cells from outside or inside body
43
Ions in DNA can cause
Mutations -> result in cell damage or death
44
Precaution to reduce risk of harm when using radioactive sources
- source shielded when not in use (lead-lined box) - protective clothing to prevent body contamination - limiting exposure time with materials - use tongs to increase distance - monitor exposure using detector badges
45
Irradiation
When someone is exposed to alpha/beta/gamma from nearby source - once they move away irradiation stops
46
Contamination
Someone gets particles of radioactive source on them or inside their body - they continue to be posed to radiation until material has all decayed or it is removed
47
Nuclear waste but be stored in
Sealed containers capable of containing radioactivity for long periods of time - since they have very long half lives
48
Danger of radiation
Mutations in living organisms Damage cell and tissue
49
Heavy nuclei (e.g. Uranium 235) can be fissioned
- large nucleus absorbs a neutron making it unstable - nucleus splits (fission) - energy released as KE of fission products
50
51
Products of fission of U-235
- 2 radioactive daughter nuclei and smaller nuclei that are not always identical to each other - small number or neutrons Combines atomic mass of daughters and neutrons equal parent
52
Chain reaction
Extra neutrons at end can induce fission in other atoms
53
When a coil of wire is toasted in magnetic field it
Induces a voltage - energy produced from fission is used to make electricity
54
Neutrons are released in
Chain reaction
55
Slower neutrons needed for
Fission
56
Graphite core around reactor in moderator for fission process
Neutrons in moderator are slowed down - increases rate of fission
57
Control rods in fission process
Control rods absorb neutrons Control rods can be moved in and out of reaction —> more or fewer neutrons available - increases or decreases rate of fission
58
Reactor vessels made of
Steel
59
Why is reactor vessels surrounded by concrete in nuclear reaction
Shielding of 5 metres prevents radiation escaping, even neutrons
60
Fusion
Process of small nuclei forced together to form heavier nucleus
61
Fusion is energy source for
Stars
62
Fusion cannot happen at
Lower temp and pressures
63
Fusion is difficult to make a
Practical fusion power station
64
Fusion explained
- 2 smaller particles join to form a larger one - More massive particles are less massive than sum of small parts - mass becomes energy which is released in fusion
65
Conditions for fusion and why
VERY high pressure/temp/KE - needed to overcome electrostatic repulsion between nuclei
66
Fission reactions used in
Nuclear power stations and submarines
67
Fusion reactions release energy
Inside stars - unable to generate on earth
68
Radioactive decay
Processes where unstable nucleus loses energy by emitting ionising particles and radiation