Atomic structure Flashcards
Explain what happens in the process of nuclear fusion.
Two lighter more unstable nuclei fuse together to form a heavier more stable nucleus. Some mass is converted to energy.
State two advantages of fuel for fusion over fuel for fission.
- Fusion uses fuel that can be more easily extracted
- Fusion uses fuel that is available in a large amount and is more renewable
Explain how the distance at which an electron orbits the nucleus may be changed.
Absorbing EM radiation. Electron moves to a higher energy level further away from the nucleus.
Give 3 examples of man-made background radiation.
- X rays
- nuclear weapons (testing)
- nuclear fallout
Explain advantage of a short half life.
Activity decreases quickly so risk of harm decreases quickly - more safe in some instances
Explain the risk of alpha radiation INSIDE the body.
Alpha is highly ionising. Increases risk of cancer as can ionise living cells and cause cell damage. Until material is removed.
Explain how smoke detectors work.
Smoke absorbs alpha radiation so signal goes off as circuit detects change.
Explain why beta and gamma can’t be used as smoke detectors.
More penetrating (than alpha) so will pass through smoke and no change will be detected.
Explain how energy released by a chain reaction is affected by moving control rods.
Moved up and down to control the number of neutrons absorbed. Lowering increases number of neutrons absorbed (by rods) so energy released decreases.
Explain the process of fission.
- Large unstable nucleus usually has to absorb a neutron as spontaneous fission is rare
- Splits forming two smaller more stable nuclei
- Releases 2/3 neutrons which can induce more fission -> chain reaction
- Releases excess energy emitted by gamma rays
What can excess energy in fission be used for?
Heat water to make steam to turn turbines and generators (for electricity for National Grid)
Give 3 natural sources of background radiation.
- Cosmic rays
- Rocks
- (Natural) gas
How is fission used to produce electricity.
A small mass of unstable uranium absorbs a neutron and releases a lot of energy continuously. This is very reliable. The energy from this process of fission is used to heat water so it’s steam turns a turbine which powers a generator to produce electricity.
Define artificial background radiation and give three examples
Deliberate radiation ie X rays, nuclear power, nuclear fall out and weapon testing
Define natural background radiation
Not deliberate radiation
Explain how gamma reacts to a magnetic field.
Count rate stays the same, gamma does not have a charge so is not affected by a magnetic field
Why are radioactive objects stored in lead lined boxes?
Lead absorbs radiation so less is emitted - safety - less risk of irradiation/contamination
Suggest three reasons why a person may receive a higher average dose of background radiation.
- Living at (high) altitudes
- Many regular X rays (than average)
- Working at a nuclear power station
Explain the ideal properties of a radioactive source for use in medical diagnosis
- Short half life so less damage to cells
- Gamma radiation emitter
- Low ionising power so less damage to cells
- Highly penetrating so can be detected outside the body
Explain how risk of internal contamination is different from external by alpha radiation
- Alpha weakly penetrating so absorbed by skin (and only a few cm in air) so externally less risk
- Internally higher risk as alpha is highly ionising so is absorbed by tissues causing greater harm/damage to cells
Compare the structure of any two isotopes
- Same number of protons and electrons
- Different number of neutrons
Explain why alpha particles deflect at an angle.
Nucleus has a positive charge and alpha particles are positively charged and like charges repel
What is the order of discovery for the atom?
Electron
Nucleus
Proton
Neutron
