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Physics IGCSE(Marc) > Radioactivity > Flashcards

Radioactivity Flashcards

1
Q

ion

A

element that has gained/lost electrons

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2
Q

isotope

A

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

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3
Q

Mass number

A

protons + neutrons

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4
Q

Atomic number

A

proton number

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5
Q

When does an atom become stable

A

when it doesn’t emit ionising radiation anymore

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6
Q

Ionising radiation

A

radiation with the ability to knock electrons off other atoms, damaging them

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7
Q

Alpa particle

A

2 protons + 2 neutrons (helium nucleus)
charge: +2
mass: 4
slow
most ionising
least penetrating (few cm of air, paper, skin)

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8
Q

Beta particle

A

electron
charge: -1
mass: 1/1800
fast (10% of speed of light)
medium ionising
medium penetrating (aluminium, bone)

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9
Q

Gamma wave

A

Electromagnetic wave

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10
Q

Gamma wave

A

Electromagnetic wave
charge: 0
mass: 0
very fast (speed of light)
least ionising
Most penetrating (Thick lead)

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11
Q

Describe how to measure radioactivity of a rock

A
  • use a GM tube + counter (if not given)
  • measure background radiation
  • measure radiation from the rock
  • subtract background
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12
Q

Describe an experiment to prove a rock emits beta radiation

A
  • use a GM tube + counter (if not given)
  • measure background radiation
  • measure radiation from the rock
  • place PAPER between rock and tube
  • reading stays the same
  • place aluminium between
  • radioactivity drops to background
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13
Q

Sources of Background radiation

A

Cosmic rays from sun
Potassium in food + drink
Radon gas in air
Radioactive rocks in buildings/mountains

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14
Q

Alpha emission

A

mass number -4
atomic number -2
U 238,92 –> α 4,2 + Th 234,90

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15
Q

Gamma emission

A

mass number stays the same
atomic number stays the same
U 238,92 –> γ 0,0 + U 238,92

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16
Q

Beta emission

A

mass number stays the same
atomic number +1
U 238,92 –> β 0,-1 + Np 238,93

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17
Q

Beta production

A

During beta emission, a neutron splits into a proton (stays in the nucleus) and an electron (leaves)

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18
Q

Activity

A

is the amount of raidation given off by an element over a period of time. Measured in Bequerells (Bq)

It is random (unpredictable)

19
Q

Half life

A

The time it takes for half of the radioactive nuclei/isotope to decay

20
Q

Uses of radioactivity

A

Radiocarbon dating
Radioactive tracers
Radiotherapy
Serilization

21
Q

Radiocarbon dating

A

One in a billion carbon atoms is Carbon - 14
Once a plant or animal dies, this carbon 14 is not replaced and it decays over time.
Carbon 14 has a half life of 5700 years.
By measuring amount of carbon -14 in a dead organism we can determine when it died.

22
Q

Radioactive tracing

A

Radioactive isotopes (technetium 99) with short half-life can be injected to humans.
Once in blood stream, emits gamma which penetrates the body and can be detected outside.
Isotope follows circulatory system, we can see any problems with heart, arteries or veins.
Same in digestive system

23
Q

Radiotherapy

A

High intensity gamma rays to treat cancer.
Placing radioactive isotope near can kill cancer cells.
But can also kill healthy cells nearby

24
Q

Sterilization

A

Gamma can be used to sterilize food and medical equipment.
Gamma penetrate food or equipment and kill bacteria on both sides.

25
Q

Dangers of radioactivity when exposed to the body

A
  • ionising radiation damages cells / tissues
  • repeated damage can lead to mutations
  • these mutations can be cancerous
26
Q

Safety precautions

A
  • minimise exposure time
  • handle sources with tongs
  • store sources in lead containers when not using
27
Q

Contamination

A

when radioactive isotope is put into an object and emits radiation from INSIDE

28
Q

Irradiation

A

when you expose an object radiation from OUTSIDE

29
Q

3 Nuclear Reactions

A

Nuclear Fission
Nuclear Fussion
Radioactive Decay

30
Q

Describe the process of nuclear fission

A
  • a slow neutron is absorved by a nucleus
  • the nucleus becomes unstable
  • the nucleus splits (fissions) into 2 daughter nuclei
  • 2 or 3 neutrons are emitted
31
Q

Explain fow one fission leads to a chain reaction

A
  • When a nucleus splits it releases neutrons
  • These neutrons are absorved by other nuclei
  • These also fission and the process repeats
32
Q

Describe the use of CONTROL RODS

A

Absorbs neutrons and take them out of the fission process

33
Q

Explain the use of CONTROL RODS

A

Controls rate of reaction (amount of energy released)

34
Q

Describe the use of GRAPHITE MODERATOR

A

Absorb the kinetic energy of the neutrons and slow them down

35
Q

Explain the use of GRAPHITE MODERATOR

A

So neutrons are slow enough to be absorbed by the nucleus (doesn’t bounce)

36
Q

Describe the use of FUEL RODS

A

To produce energy

37
Q

Describe the use of THICK CONCRETE SHIELD

A

Absorb neutrons and other radiations

38
Q

Explain the use of THICK CONCRETE SHIELD

A

Radiation could lead to ionisation and cell mutation/cancer

39
Q

Describe the use of GAS

A

Absorn heat energy and transfer the energy into the turbine

40
Q

How do we control nuclear fission

A
  • WHen control rods are fully inserted, chain reaction almost stops + heat production is low.
  • When control rods are withdrawn, rate of fission increases and more heat energy is produced
41
Q

Describe Nuclear Fusion

A
  • 2 small nuceli collide
  • join to create a larger nucleus
42
Q

Nuclear fusion equation

A

H 2,1 + H 3,1 –> He 4,2 + n 1,0

43
Q

State and explain the conditions needed for a nuclear fusion reaction

A

HIGH TEMPERATURE:
- Nuclei have a high kinetic energy
- to overcome the electrostatic repulsion
- between the positively charged nuclei
HIGH PRESSURE:
- lead to high density
- lead to high rate of collisions

Physics IGCSE(Marc) (6 decks)

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