Topic 11 Flashcards
What two processes can cause electrons to change energy levels
- Large heat increase
- The presence of an electrical field
What are the four scenarios in which an atom may become unstable
- The atom having too many neutrons
- The atom having too few neutrons
- The atom having too much mass
- The atom having too much energy
How do unstable nuclei become more stable
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
What are the constituents of an alpha particle
Two protons and two neutrons
What are penetration capabilities of alpha radiation
Alpha particles are weakly penetrating and so are stopped by a few centimetres of air or a sheet of paper
What does beta-minus radiation consist of
High-energy electrons
What does beta-plus radiation consist of
High-energy positrons
What are the penetration capabilities of beta-minus radiation
Beta-minus radiation has medium penetrative capabilities and is stopped by a few mm of aluminium or around 1 m of air
What are the penetration capabilities of beta-plus radiation
Beta-plus radiation is almost instantaneously annihilated by electrons and so has virtually zero range
What is gamma radiation
Gamma radiation is a form of high-energy electromagnetic radiation
What charge do gamma rays have
Gamma rays are a form of electromagnetic radiation and so don’t have a charge
Which type of radiation is most ionising
Alpha radiation
Which type of radiation is most weakly ionsing
Gamma radiation
What type of radiation travels the fastest and at what speed
Gamma radiation travels the fastest since it is a type of electromagnetic radiation and so travels at the speed of light
Under what circumstance is alpha radiation emitted
When a nucleus has too much mass
Under what circumstance is beta-minus radiation emitted
Beta-minus radiation is emitted when a nucleus has too many neutrons
Under what circumstance is beta plus radiation emitted
Beta-plus radiation is emitted when a nucleus has too many protons
Under what circumstance is gama radiation emitted
Gamma radiation is emitted when a nucleus has too much energy
What are the penetrative capabilities of gamma radiation
Gamma radiation is highly penetrative but is absorbed by several inches of lead or several metres of concrete
Explain the process of beta-minus decay
Beta-minus decay is where a neutron in the nucleus turns into a proton, and releases an electron and an electron antineutrino
Explain the process of beta-plus decay
Beta-plus decay is where a proton in the nucleus turns into a neutron, and releases a position and an electron neutrino
How does the mass of a nucleus compare to the sum of the individual masses of it s constituents
The mass of the nucleus is always less the sum of the individual masses of its constituents
What is the name given to the difference in the mass of a nucleus and its individual constituents
The mass defect
Explain why there is a mass defect in nuclei
The mass defect is a result of some of the mass being converted into energy used to hold the nucleus together
What is the name for the value of the energy required to hold a nucleus together
Binding energy
How can the mass defect be used to calculte the binding energy of a nucleus
By substituting the mass defect into Einstein’s mass energy equation
Why isn’t it useful to compare binding energies for different nuclei
Different nuclei have different numbers of nucleons
What is a more useful measure used to compare the binding energies of different nuclei
The binding energy per nucleon
State the equation used to calculate the binding energy per nucleon of a nucleus
Binding energy per nucleon = Binding energy / Number of Nucleons
What is the relationship between the stability of a nucleus and its binding energy per nucleon
The larger the binding energy per nucleon, the more stable the nucleus will be
What is the most stable nucleus
Iron
Name two nuclear processes thaat can be used to generate energy
- Nuclear Fission
2. Nuclear Fusion
What are the two types of fission
- Spontaneous fission
2. Induced fission
Explain the basic process of induced fission
A large nucleus absorbs a thermal neutron causing it to split into two smaller nuclei, releasing energy and at least one neutron
Explain the basic process of nuclear fusion
Two smaller nuclei join together to form a larger one, and releases energy in the process
Why is nuclear fusion is not currently a feasible method of energy production
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
Where does nuclear fusion constantly take place
In stars (for example, the sun)
