Atoms and nuclear radiation

• what causes an atom to be radiation

  • an unstable nuclei
• what is activity

  • the rate at which an unstable nuclei from a source decays
• what is activity measured in

  bequerels
• how to detect radiation

  • geiger counter connected to a geiger miller tube
• what are the types of radiation

  • gamma
  • alpha
  • beta
  • neutron
• what is alpha particles

  • same as a helium nucleus
  • 2 neutrons and 2 protons
  • Range in air - a few cm - not very penetrating
  • stopped by paper
  • highly ionising
• what is beta particle

  • electron
  • can penetrate around 10 cm in air
  • stopped by a few mm of aluminium
  • somewhat ionising
• what is gamma radiation

  • electromagnetic wave
  • not ionising
  • can penetrate far through the air
  • must be stopped by thick led
• what are the uses of radiation?

  • nuclear fission energy production
  • medical procedures
  • smoke detectors
• how do smoke detectors work?

  • contain alpha particles which can only ionise through the air within the detector
  • this creates a current
  • the alpha emitter is blocked when smoke enters the detector and the alarm is triggered by a microchip
• what happens in alpha decay?

  • alpha particle and daughter nucleus is produced from an unstable nucleus
  • MASS NUMBER DECREASES BY 4
  • ATOMIC NUMBER DECREASES BY 2
• what happens during beta decay?

  • neutron turns into a proton and an electron
  • the electron is emitted
• what happens during gamma decay?

  • gamma ray is emmitted from an unstable nucleus
  • nucleus gets weaker but structure stays the same
• Why can a nucleus decay not be predicted?

  • it is a random process and there is an equal chance of it decaying
  • the rate of decay is UNAFFECTED by surroundings.
• how can the random nature of decay be observed?

  • place a geiger miller counter near the source. it will show that the counts are irregular and provide evidence for the unpredictability for the decay.
• what is half life

  The time it takes for the number of nuclei of a sample of radioactive isotopes to decrease by half
• what is contamination

  • the unwanted presence of materials containing radioactive atoms on other materials
  • ie you get radiation on your jumper
• what is irradiation

  • the process of exposing an object to beta, gamma or alpha radiation
  • can kill living cells
• what are the uses of irradiation

  • sterilising surgical equipment
  • food can be irradiated to kill any micro-organisms within it - makes it last longer without it going mouldy
• does irradiation make an object radioactive?

  • NO
  • ONLY CONTAMINATION makes an object radioactive
• how can irradiation be prevented

  • use shielding ie lead clothing
• how can contamination be prevented

  • handle sources safely
  • wear airtight clothing
• why is radiation dangerous

  • can mutate cells and cause cancer
• why was Marie Curies discoveries on radioactivity PEER REVIEWED?

  • other scientests learned from her findings
  • her work was checked for accuracy
• how has our knowlage of radioactivity developed overtime?

  • we now know the dangers of it
  • before, people thought it was good for you.