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Physics Paper 1 > Topic 4: Atomic Structure > Flashcards

Topic 4: Atomic Structure Flashcards

1
Q

4.1

A

Atoms and Isotopes

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2
Q

Give an approximation for the radius of an atom.

A

1 x 10(-10) metres

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3
Q

Give two ways that an atom’s electron arrangement can be changed.

A
  1. Absorbing electromagnetic radiation
  2. Emitting electromagnetic radiation
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4
Q

4.2

A

Atoms and Nuclear Radiation

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5
Q

Why do unstable nuclei give out radiation?

A
  • Unstable nuclei undergo decay to become more stable
  • As they release radiation their stability increases
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6
Q

What is count-rate?

A

The number of radioactive decays per second for a radioactive source.

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7
Q

Given an example of a detector that may be used to measure count-rate.

A

Geiger-Muller tube

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8
Q

What is the range of an alpha particle through air?

A

A few centimetres (normally in the range of 2-10 cm)

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9
Q

What will stop beta radiation from passing through a point?

A
  • A thin sheet of aluminium
  • Several metres of air
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10
Q

What will stop gamma radiation from passing through a point?

A
  • Several centimetres of lead
  • A few metres of concrete
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11
Q

Which type of radiation is most ionising?

A

Alpha radiation

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12
Q

Which type of radiation is least ionising?

A

Gamma radiation

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13
Q

Describe the nature of radioactive decay.

A
  • Random
  • Which nuclei decays and when is determined only by chance
  • It is impossible to predict which nuclei will decay and when
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14
Q

Define the half-life of a radioactive isotope.

A
  • The time it takes for the number of unstable nuclei in a substance to halve
  • The time it takes for the count rate from a sample to fall to half its initial level
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15
Q

What is radioactive contamination?

A

The presence of unwanted radioactive nuclei on other materials.

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16
Q

What is irridation?

A
  • The process of exposing a material to nuclear radiation
  • The material does not become radioactive
17
Q

Why is it important for the results of studies on the effects of radiation to be published and shared with other scientists?

A
  • To allow the findings to be independently checked
  • This is known as peer review
18
Q

4.3

A

Hazards and Uses of Radioactive Emissions and Background Radiation (Physics Only)

19
Q

Give 4 sources of background radiation.

A
  1. Rocks
  2. Cosmic rays from space
  3. Nuclear weapon testing
  4. Nuclear accidents
20
Q

How should background radiation be dealt with in calculations?

A

The background count should be subtracted from any readings before calculations (half life etc.) are attempted.

21
Q

Why might the radiation dosage that different people experience differ?

A
  • Some occupations involve working with radiation
  • Background radiation differs with location due to things such as the locality of nuclear power stations or radiation related testing
22
Q

Why are isotopes with long half-lives particularly harmful?

A
  • They remain radioactive for much longer periods of time
  • They must be stored in specific ways to avoid humans and the environment from being exposed to radiation for too long
23
Q

State two uses of nuclear radiation in the field of medicine.

A
  1. Examining of internal organs
  2. Controlling and destroying unwanted tissue
24
Q

Explain the process of radiotherapy.

A
  • Gamma emitters direct gamma rays at the cancerous cells
  • The cancerous cells absorb the radiation and are killed
25
Q

How are medical tracers chosen?

A
  • They should have a short half life and decay into a stable isotope which can be excreted.
  • They should only release gamma radiation since it is weakly ionising and can easily pass through body tissue without damaging it.
26
Q

4.4

A

Nuclear Fission and Fusion (Physics Only)

27
Q

What is nuclei fission?

A

The splitting of large, unstable nuclei to form smaller more stable nuclei (+ the emission of spare neutrons).

28
Q

What usually needs to happen to induce fission?

A
  • The unstable nuclei must absorb a neutron
  • Spontaneous fission (where no neutron absorption occurs) is rare
29
Q

What are the three main components of the core a nuclear reactor?

A
  1. Fuel rods
  2. Control rods
  3. Moderator
30
Q

What is nuclear fusion?

A

The joining of two light nuclei to produce a heavier nuclei and release energy.

31
Q

Which releases more energy, nuclear fission or nuclear fusion?

A

Nuclear fusion

32
Q

Explain the difficulty of generating energy through nuclear fusion.

A

Fusion requires very high temperatures which in itself requires large quantities of energy and also requires casing which can withstand them.

33
Q

Explain why nuclear fusion is currently not a viable way to produce energy on Earth.

A

With current equipment/techniques, the energy is required is greater than the energy produced, resulting in a net energy loss.

Physics Paper 1 (4 decks)

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