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Physics GCSE > Radioactivity > Flashcards

Radioactivity Flashcards

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1
Q

describe the plum pudding model (currant bun)

A

A sphere of positive charge with randomnly embedded negative electrons

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2
Q

nuclear model properties

A
  • A small centrally situated positive nucleus
  • electrons were found in energy levels (“shells”)
  • It also contained neutrons discovered by James Chadwick
  • Electrons occupy energy levels (2,8,8,2)
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3
Q

Describe the results and conclusions of Rutherford’s gold foil scattering experiment

A
  • Most of the alpha particles (approximately 90%) passed straight through the gold foil
    conclusion: the atom has space
  • A few particles (approximately 8%) approached the gold foil and deflected/ deviated at different angles
    conclusion: The atom has charge (alpha is positive and the nucleus of an atom is positive- repulsion)
  • One or two of the alpha particles were reflected when striking the gold foil
    conclusion: The mass of the atom is concentrated in the nucleus- change in momentum
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4
Q

RADioACtivity

A

The spontaneous/ random decay/ disintegration of an unstable nucleus by emitting alpha particles, beta particles and gamma radiation (and also neutrons).

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5
Q

When were neutrons discovered?

A

In 1930

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6
Q

When is an isotope highly reactive?

A

When the number of neutrons greatly exceeds the number of protons.

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7
Q

What makes a nucleus unstable?

A

When the number of protons is different from the number of neutrons. More protons than neutrons or fewer protons than neutrons.

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8
Q

Radioactivity is measured in

A

Becquerel (one decay/ disintegration per second)

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9
Q

How do you detect radioactivity?

A

Using a Geiger Muller tube/ counter and cloud chamber

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10
Q

Alp^2hea particle

A
  • Helium nucleus (positively charged) - 2 protons and 2 neutrons
  • Lowly penetrating (can be stopped by skin or thin sheet of paper)
  • used in smoke alarms/ detectors
  • highly ionising
  • short range (approximately 5 cm)
  • approximately 10% the speed of light
  • alpha particles are charged: any charged particle can be deflected by a magnetic or electric field.
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11
Q

North pole

A

negative

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12
Q

South pole

A

positive

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13
Q

examples of radioactive materials

A

americinium, actinium

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14
Q

What radioactive material has a half life of 6 hours?

A

Technetium

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15
Q

Precautions when handling radioactive materials

A

1, A notice on the door to indicate radioactive use
2, Observe the Alara principle- keep exposure as low as reasonably achievable
3, Use tongs when handling
4, Safely store in lead containers

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16
Q

bET^2a

A
  • a fast moving electrons (e-) can be deflected by an electric or magnetic field
  • Beta particles are more penetrating than alpha but less ionising (charge of -1)
  • stopped by very thin aluminium sheets, have a longer range than alpha
  • approximately 90% the speed of light (2.7 x 10^8)
  • Beta particles are used to measure the thickness of materials eg: paper, metals
  • Beta particles can also be used as radioactive tracers (can be used to detect radioactivity) eg: health and detection of breakages in pipes.
17
Q

GaMMA

A
  • an electromagnetic wave/ radiation
  • zero charge, zero mass
    conclusion: cannot be deflected by an electric or magnetic field
  • most penetrating, least ionising (not charged)
  • may be stopped by thick lead materials
  • It travels at the speed of light (3x10^8 m/s)
  • used in sterilisation of medical equipment
  • can kill micro-organisms to preserve food and increase the shelf life (small dosage)
  • It is used in radiography to kill cancerous cells due to its penetrating power.
18
Q

Half life

A

The average time taken for the start value/ activity/ parent nuclei to decrease to half its’ value.

19
Q

Uses of half lives

A
  • medical purposes:
    technetium- 99. Has a half life of 6 hours (does not expose the body to a significant degree of ionisation)
  • determination of the age of materials- carbon dating
  • smoke detectors: materials must have relatively long half lives
  • radioactive tracers- this can help to detect breakages in pipes and monitor the growth of plants
  • MRI- magnetic resonance imaging
20
Q

BaCkGRouND radiation

A
  • RADON- approximately 50% of all background radiation
  • Building and Rock
  • medical supplies
  • Cosmic radiation
  • Geothermal (energy from hot rocks)
  • fooD and Drinks
  • Nuclear power stations/ Nuclear distasters
21
Q

Age of sample =

A

actual half life x number of half lives

22
Q

Vanderwaal’s forces

A

intermolecular forces

23
Q

irradiation

A

exposing an object to nuclear radiation. The object/ body does not becomes radioatvie to contaminate other objects. eg: X-rays, gamma rays

24
Q

contamination

A

unwanted presence of radioactive materials on other objects. The other objects become radioactive. This creates a hazardous situation which creates a health risk.

25
Q

Nuclear disasters

A

Chernobyl (Ukraine) and Fukushima (Japan)

26
Q

What is radiation does measured in?

A

Sieverts (Sv)

27
Q

Describe the process of nuclear fission

A

The splitting of a large nucleus using neutron bombardment (collision) into two smaller nuclei and further neutrons are released. Kinetic energy is released. It takes place in a nuclear reactor (uranium or plutonium).

28
Q

Nuclear fission definition

A

The splitting of a large nucleus using neutron bombardment (collision) into two smaller nuclei.

29
Q

Nuclear fission definition

A

Nuclear fission is the joining together of two small nuclei to form a large nucleus and kinetic energy is released initially (Tokomak energy- super magnetcs to withstand these high temperatures).

30
Q

nuclear fusion occurs in the formation of what?

A

stars

31
Q

Chain reaction

A

After the first fission reaction, further neutrons are released which can collide/ bombard with other large nucle, sustaining the reaction. This is called a chain reaction.

32
Q

Critical mass (uranium or plutonium)

A

The minimum mass that the nuclear fuel must have in order to cause a chain reaction.

33
Q

What happens in a nuclear reactor?

A

The slow-moving neutron collides with the nuclear fuel.

34
Q

What are the components of a nuclear reactor?

A

concrete/lead shell, coolant, control rod, nuclear fuel, moderator

35
Q

What is the purpose of a concrete/lead shell?

A

to contain the high temperatures and to prevent any stray radiation from escaping

36
Q

What is the purpose of a coolant in a nuclear reactor?

A

It cools down the temperature and acts as a heat exchanger (usually uses water)- transfers thermal energy from reactor to boiler).

37
Q

control rod

A

They can be raised of lowered depending on the temperature. They ABSORB neutrons to regulate the fission reaction made from boron or cadmium.

38
Q

purpose of nuclear fuel (uranium or plutonium) in nuclear reactors

A

They provide the radioactive source for the fission reaction.

39
Q

moderator (water/ graphite)

A

It slows down neutrons to sustain the chain reaction.

Physics GCSE (11 decks)

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