Atoms and nuclear radiation

• What is radioactive decay?

  The process of unstable nuclei emitting radiation
• Why are some atomic nuclei unstable?

  Due to an imbalance in nuclear forces
• What is an example of an unstable isotope?

  Carbon-14
• How does Carbon-14 differ from Carbon-12?

  Carbon-14 has two extra neutrons
• What happens when unstable nuclei emit radiation?

  They become more stable
• What is the term for the process of emitting radiation?

  Radioactive decay
• Is radioactive decay a predictable process?

  No, it is a random process
• Which statement about isotopes is not true?

  Scientists can predict when a nucleus will decay
• What defines the activity of a radioactive source?

  • The rate at which unstable nuclei decay
  • Measured in Becquerels (Bq)
  • 1 Bq = 1 nucleus decaying per second
• What is the symbol for Becquerels?

  Bq
• How many unstable atoms decay in 2 minutes if the activity is 2000 Bq?

  240,000 unstable nuclei
• What device is used to detect radiation?

  Geiger-Muller tube
• What does a Geiger counter measure?

  The count-rate of radiation detected
• What is count-rate?

  Number of decays recorded each second
• If a Geiger-Muller tube counts 16,000 decays in 1 hour, what is the count rate?

  4.5 decays per second
• What are the types of radiation emitted from unstable nuclei?

  • Alpha particles
  • Beta particles
  • Gamma rays
  • Neutrons

  
• What is the symbol for alpha particles?

  α
• What are alpha particles equivalent to?

  A helium nucleus
• What charge do alpha particles have?

  +2
• What is the symbol for beta particles?

  β
• What are beta particles?

  Fast-moving electrons
• What charge do beta particles have?

  -1
• What is the symbol for gamma rays?

  γ
• What type of radiation are gamma rays?

  Electromagnetic waves
• What is the charge of gamma rays?

  They have no charge
• What is the symbol for a neutron?


  n
• What is the charge of neutrons?

  They have no charge
• What are the properties of alpha, beta, and gamma radiation?

  • Alpha: least penetrating, most ionising
  • Beta: moderate penetrating, moderate ionising
  • Gamma: most penetrating, least ionising

  
• How does alpha radiation penetrate materials?

  It is stopped by paper

  
• How does beta radiation penetrate materials?

  It is stopped by a few millimetres of aluminium

  
• How does gamma radiation penetrate materials?

  It can pass through aluminium

  
• What is the range of alpha radiation in air?

  A few centimetres
• What is the range of beta radiation in air?

  A few tens of centimetres
• What is the range of gamma radiation in air?

  Infinite range
• Why is alpha radiation used in smoke detectors?

  It is absorbed by smoke, triggering the alarm

  
• Why are alpha particles suitable for smoke detectors?

  • Strongest ioniser
  • Weakly penetrating
  • Absorbed by smoke
• Why wouldn't beta or gamma radiation be used in smoke detectors?

  They would pass through smoke without detection
• What are the uses of radiation?

  • Producing electricity through nuclear fission
  • Medical procedures
  • Testing materials
  • Determining age of artefacts
  • Smoke detectors
• What is the misconception about gamma radiation?

  It is the most dangerous due to penetration
• What is the most harmful aspect of radiation?

  Its ionising capability