particles and radiation

• an alpha particle:

  • consists of 2 neutrons and 2 protons and is equivalent to a helium nucleus
  • is high ionising but has low penetrating power approximately 1-2cm in the air
• beta:

  • is a high speed electron ejected from a nucleus as a neutron turns into a proton
  • is medium ionising and has medium penetrating power
  • has a range of approximately 15cm in the air
• an alpha particle:

  • consists of 2 neutrons and 2 protons and is equivalent to a helium nucleus
  • is high ionising and has low penetrating power
  • has a range of 1-2cm in the air
• gamma:

  • is electromagnetic radiation from the nucleus
  • is low ionising and has high penetrating power
  • has a range of many kms in the air
• what is ionisation?

  the formation of charged particles from neutral molecules or atoms by adding or removing electrons
• what is excitation?

  transferring energy to atoms or molecules to excite electrons to a higher energy level
• what is activity?

  the rate at which a radioactive source decays (measured in Bq)
• what is count-rate?

  the number of radioactive decays recorded each second
• what is half-life?

  the time taken for half the unstable nuclei in a sample to decay
• what is an isotope?

  an atom of the same element with the same number of protons but a different number of neutrons
• what are radio pharmaceuticals?

  therapeutic drugs that incorporate radioisotopes- used to treat or diagnose disease
• what equipment do you use to measure radioactivity?

  a Geiger-Muller tube