atoms + radiation

• what is an isotope?

  an isotope is an atom with the same number of protons but a different number of neutrons
• what are gamma rays?

  an electromagnetic wave
• what are alpha particles?

  a helium nucleus
• what are beta particles?

  fast-moving electron
• what is the mass number of an element?

  number of protons + number of neutrons
• what is the atomic number of an element?

  the number of protons and the number of electrons
• how do you measure radiation?

  a geiger-muller tube and counter
• what is the half-life of an element?

  the time it takes for the amount of radiation emitted by a source to halve
• what is radiation dose measured in?

  sieverts (Sv)
• where does background radiation come from?

  1. naturally occuring unstable isotopes
  2. radiation from space (cosmic rays)
  3. radiation due to human activity - nuclear explosions or nuclear waste
• what is irradiation?

  exposure to a radioactive source, does not make something radioactive
• what is contamination?

  when unwanted radioactive atoms get onto or into an object or human
• which type of radiation is most harmful inside the body?

  alpha radiation
• why are alpha sources so damaging to the body?

  their damage is very localised and they are highly ionising
• what does radiation do to the body?

  they ionise atoms and molecules which leads to tissue damage
• why are beta and gamma sources most dangerous outside the body?

  they can penetrate the body and reach organs
• what do low doses of radiation do?

  they can create mutant cells which divide uncontrollably (cancer)
• what do higher doses of radiation do?

  they kill cells completely causing radiation sickness
• what type of radiation do medical tracers use?

  gamma sources
• how do medical tracers work?

  specific radioactive isotopes can be injected or swallowed and then followed by an external detector
• what radiation types are used in radiotherapy?

  gamma rays and beta sources
• how is beta radiation used in radiotherapy?

  beta-emitting implants can be put next to or inside tumours to kill the cancer cells
• how are gamma rays used in radiotherapy?

  gamma rays are directed carefully at the right dosage to kill cancer cells without damaging too many normal cells
• what is nuclear fusion?

  two light, smaller nuclei collide at high speed and fuse to create a larger and heavier nucleus
• what is nuclear fission?

  the splitting of a large and unstable atom into two smaller atoms