atomic physics

• What is the nucleus of an atom made up of?

  Protons and neutrons
• What charge do electrons have?

  Negatively-charged
• What is the mass of an electron?

  1/2000
• What is the charge of a proton?

  1+
• What is the mass of a neutron?

  1
• What does the Plum Pudding Model propose about atomic structure?

  • Atom is a ball of positive charge
  • Electrons are embedded within it
  • Overall, the atom has a neutral charge
• Who proposed the Plum Pudding Model?

  JJ Thompson
• What happens during the alpha scattering experiment?

  Alpha particles are fired at gold foil and detected on a screen
• What does the deflection of alpha particles in the gold foil experiment indicate?

  There is something else interfering with the particles
• What is background radiation?

  • Naturally-occurring particles isotopes
  • Decay over time
  • Release radioactive particles or waves
• What is the largest natural source of background radiation?

  Radon gas in the atmosphere (51%)
• What percentage of background radiation comes from food and drink?

  12%
• What is the percentage contribution of cosmic rays to background radiation?

  10%
• What is the percentage of background radiation from medical usage?

  12%
• What is the biggest danger when encountering radiation?

  Ionisation
• What is ionisation?

  • Process of gaining a charge
  • Involves losing or gaining electrons
• What are the safety measures for handling radioactive sources?

  • Only authorized persons handle sources
  • Users wear exposure badges
  • Gloves and tongs must be used
  • Never direct sources towards people
  • Store sources in lead-lined boxes when not in use
• What device is used to detect radioactive particles?

  Geiger-Müller (G-M) counter
• What should be done before starting an experiment with radioactive sources?

  Take the background radiation measurement
• What are the types of radiation and their characteristics?

  • Alpha: Strongly ionising, low penetration, stopped by paper
  • Beta: Moderately ionising, moderate penetration, stopped by aluminium
  • Gamma: Weakly ionising, high penetration, stopped by lead
• What is the atomic mass of an alpha particle?

  4
• What is the speed of alpha particles compared to the speed of light?

  0.1 times the speed of light
• What happens during alpha decay?

  An alpha particle is lost from the nucleus
• What occurs during beta decay?

  A neutron splits into a proton and an electron
• What is emitted during gamma decay?

  Energy
• How do charged particles interact with magnetic and electric fields?

  • Charged particles create magnetic fields when moving
  • Beta particles are repelled in the opposite direction to alpha
  • Alpha particles are attracted to negative terminals
  • Beta particles are attracted to positive terminals
  • Gamma rays are unaffected by both fields
• What is half-life in the context of radioactive isotopes?

  The time taken for the number of radioactive nuclei to halve
• How is the count rate of radioactive decay measured?

  In counts per minute (cpm), counts per second, or Becquerels (Bq)
• What is the difference between contamination and irradiation?

  • Irradiation: Exposure to ionising radiation
  • Contamination: Spread of radioactive source
  • Contamination is often more problematic
• What can ionising radiation damage in living tissue?

  Molecules that make up the cells
• What can repeated damage from ionising radiation cause?

  Cells to mutate or die
• Why are alpha particles of little danger unless taken into the body?

  They cannot penetrate the skin
• What is a common source of alpha particles that can be inhaled?

  Radon gas
• What are the safety measures to reduce risk in the laboratory when handling radioactive sources?

  • Keep distance from sources
  • Limit exposure time
  • Use protective clothing
• What are the medical uses of radioactive substances?

  • Radioactive tracers for imaging
  • Radiotherapy for cancer treatment
• What is a radioactive medical tracer?

  A substance injected to detect internal damage
• What is the purpose of a gamma knife in radiotherapy?

  To destroy cancerous cells
• What is nuclear fission?

  The act of splitting a large nucleus
• What is released during nuclear fission?

  Energy and stray neutrons
• What is a nuclear chain reaction?

  • Neutrons released in fission start new fission reactions
  • Continues releasing energy
  • Must be controlled in a reactor