Topic 11 Flashcards

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1
Q

What two processes can cause electrons to change energy levels

A
  • Large heat increase

- The presence of an electrical field

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2
Q

What are the four scenarios in which an atom may become unstable

A
  1. The atom having too many neutrons
  2. The atom having too few neutrons
  3. The atom having too much mass
  4. The atom having too much energy
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3
Q

How do unstable nuclei become more stable

A

Unstable nuclei are radioactive, so emit radiation in order to become more stable.
They type of radiation they emit depends on what makes them unstable

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4
Q

What are the constituents of an alpha particle

A

Two protons and two neutrons

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5
Q

What are penetration capabilities of alpha radiation

A

Alpha particles are weakly penetrating and so are stopped by a few centimetres of air or a sheet of paper

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6
Q

What does beta-minus radiation consist of

A

High-energy electrons

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7
Q

What does beta-plus radiation consist of

A

High-energy positrons

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8
Q

What are the penetration capabilities of beta-minus radiation

A

Beta-minus radiation has medium penetrative capabilities and is stopped by a few mm of aluminium or around 1 m of air

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9
Q

What are the penetration capabilities of beta-plus radiation

A

Beta-plus radiation is almost instantaneously annihilated by electrons and so has virtually zero range

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10
Q

What is gamma radiation

A

Gamma radiation is a form of high-energy electromagnetic radiation

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11
Q

What charge do gamma rays have

A

Gamma rays are a form of electromagnetic radiation and so don’t have a charge

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12
Q

Which type of radiation is most ionising

A

Alpha radiation

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13
Q

Which type of radiation is most weakly ionsing

A

Gamma radiation

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14
Q

What type of radiation travels the fastest and at what speed

A

Gamma radiation travels the fastest since it is a type of electromagnetic radiation and so travels at the speed of light

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15
Q

Under what circumstance is alpha radiation emitted

A

When a nucleus has too much mass

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16
Q

Under what circumstance is beta-minus radiation emitted

A

Beta-minus radiation is emitted when a nucleus has too many neutrons

17
Q

Under what circumstance is beta plus radiation emitted

A

Beta-plus radiation is emitted when a nucleus has too many protons

18
Q

Under what circumstance is gama radiation emitted

A

Gamma radiation is emitted when a nucleus has too much energy

19
Q

What are the penetrative capabilities of gamma radiation

A

Gamma radiation is highly penetrative but is absorbed by several inches of lead or several metres of concrete

20
Q

Explain the process of beta-minus decay

A

Beta-minus decay is where a neutron in the nucleus turns into a proton, and releases an electron and an electron antineutrino

21
Q

Explain the process of beta-plus decay

A

Beta-plus decay is where a proton in the nucleus turns into a neutron, and releases a position and an electron neutrino

22
Q

How does the mass of a nucleus compare to the sum of the individual masses of it s constituents

A

The mass of the nucleus is always less the sum of the individual masses of its constituents

23
Q

What is the name given to the difference in the mass of a nucleus and its individual constituents

A

The mass defect

24
Q

Explain why there is a mass defect in nuclei

A

The mass defect is a result of some of the mass being converted into energy used to hold the nucleus together

25
Q

What is the name for the value of the energy required to hold a nucleus together

A

Binding energy

26
Q

How can the mass defect be used to calculte the binding energy of a nucleus

A

By substituting the mass defect into Einstein’s mass energy equation

27
Q

Why isn’t it useful to compare binding energies for different nuclei

A

Different nuclei have different numbers of nucleons

28
Q

What is a more useful measure used to compare the binding energies of different nuclei

A

The binding energy per nucleon

29
Q

State the equation used to calculate the binding energy per nucleon of a nucleus

A

Binding energy per nucleon = Binding energy / Number of Nucleons

30
Q

What is the relationship between the stability of a nucleus and its binding energy per nucleon

A

The larger the binding energy per nucleon, the more stable the nucleus will be

31
Q

What is the most stable nucleus

A

Iron

32
Q

Name two nuclear processes thaat can be used to generate energy

A
  1. Nuclear Fission

2. Nuclear Fusion

33
Q

What are the two types of fission

A
  1. Spontaneous fission

2. Induced fission

34
Q

Explain the basic process of induced fission

A

A large nucleus absorbs a thermal neutron causing it to split into two smaller nuclei, releasing energy and at least one neutron

35
Q

Explain the basic process of nuclear fusion

A

Two smaller nuclei join together to form a larger one, and releases energy in the process

36
Q

Why is nuclear fusion is not currently a feasible method of energy production

A

Nuclear fusion requires very high temperatures in order to overcome the electrostatic force between the nuclei. THis makes it hard to contain and means more energy must be inputted to heat the nuclei then is generated

37
Q

Where does nuclear fusion constantly take place

A

In stars (for example, the sun)