Radiation

• Isotopes - element with the same number of protons but a different number of neutrons

  -same atomic number

  -different mas number
• Some are unstable = decay and give out radiation

  ionising radiation - radiation that can knock electrons off atoms

  how ionising it is depends how readily it can do that
• Alpha radiation - alpha particle emitted from nucleus of a radioactive nuclei.

  -most from 2 protons and 2 neutrons

  -cant travel too far in air

  -least penetrating ( stopped by skin and paper)

  -highly ionising -> size

  • more dangerous in body - highly ionising , lots of damage
  • less dangerous outside body -> cannot penetrate the skin
• Beta radiation - fast moving electron

  • can be stopped by aluminium
  • emitted by atom when a neuron splits into a proton and an electron
  • less dangerous inside body - some radiation able to escape
  • more dangerous outside -> penetrate the skin
• Gamma wave - wave of radiation

  • most penetrating
  • stopped by thick lead and concrete
  • least dangerous inside body, most will pass out and is least ionising
  • more dangerous outside -> penetrate the skin
• chart :

  
• Half life - time taken for number of radioactive nuclei in an isotope to half

  -never know when nuclei will decay = random

  Radioactivity decay measured in Becquerels

  1Bq = one decay per second
• Half life graphs always have this shape

  
• Irradiation - material are near radioactive sources

  • source places inside a lead-lined box to avoid this

  people who work with radioactive sources always stay behind a lead barrier, be in a different room, use a remote - controlled arm
• Contamination - unwanted radioactive atoms get onto an object , possible for radioactive particle to get inside the body

  -wear protective clothes