Topic 7 - Types of Radiation

• What do all forms of the same element have in common?

  The number of protons.
• What is the name given to the number of protons in an atom?

  Atomic Number
• What is an atom's mass number?

  The total number of protons and neutrons in the atom.
• What is an isotope of an atom?

  An atom of an element that has a different number of neutrons (so a different mass number), but the same number of protons.
• Why are some atomic nuclei unstable?

  • There is an imbalance between the numbers of protons and neutrons.
  • They contain too much energy.
• Why do unstable nuclei give out radiation?

  • Unstable nuclei undergo decay to become more stable.
  • As they release radiation their stability increases.
• What is the name of the process in which an unstable nucleus gives out radiation to become more stable?

  Radioactive decay.
• State four types of nuclear radiation.

  1. Alpha particles
  2. Beta particles
  3. Gamma rays
  4. Neutrons
• What are the constituents of an alpha particle?

  • Two protons and two neutrons
  • It is the same as a helium nucleus
• What is the range of an alpha particle through air?

  A few centimetres (normally in the range of 2-10 cm).
• What will stop beta radiation from passing through a point?

  • A thin sheet of aluminium
  • Several metres of air
• What will stop gamma radiation from passing through a point?

  • Several centimetres of lead
  • A few metres of concrete
• Which type of radiation is most ionising?

  Alpha radiation
• Which type of radiation is least ionising?

  Gamma radiation.
• Which type of radiation is least penetrating?

  Alpha radiation.
• Which type of radiation is most penetrating?

  Gamma radiation.
• State any changes to mass or charge that occur due to the emission of a gamma ray.

  Both mass and charge remain unchanged.
• State any changes to mass or charge that occur due to the emissions of a gamma ray.

  Both mass remains unchanged, charge increases by 1.
• State any changes to mass or charge that occur due to the emission of a gamma ray.

  Mass decreases by 4 and charge decreases by 2.
• Describe the nature of radioactive decay.

  • Random
  • Which nuclei decays and when is determined only by chance
  • It is impossible to predict which nuclei will decay and when
• State two techniques that can be used when carrying out experimental work, to combat the random nature of decay.

  1. Take repeat-readings
  2. Carry out the experiment out over a long period of time
• Why is radioactive waste such a problem?

  • It remains radioactive for thousands of years.
  • It can cause harm to living cells so must be stored appropriately.
• Give 4 sources of background radiation.

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