radioactivity

• alpha

  • 2 protons / 2 neutrons
  • charge - 2+
  • mass - 4
  • helium nucleus
  • strongly ionising
  • weakly penetrating
• beta

  • neutron becomes proton
  • emits a high energy electron
  • charge - 1 minus
  • mass - 0
  • moderately ionising
  • moderately penetrating
• gamma

  • a wave
  • charge - 0
  • mass - 0
  • weakly ionising
  • highly penetrating
• half life - time taken for the rate of decay to halve

  • recorded by a geiger muller tube
  • count number - number of decays each second
• alpha radiation - most ionising / most damage to cells

  • cause mutations
  • lead to cancer
• safety precautions with radiation

  • use tongs
  • store in lead lined box
  • overalls / goggles / gloves
• radiation sickness - lots of radiation exposure

  • vomiting
  • tiredness
  • hair loss
• radio therapy - kills cancerous cells
• external radiotherapy

  • exposed to gamma rays outside of body
  • only cancerous site gets a high dose of radiation
• internal radiotherapy

  • inside body
  • radiation source emits beta particles and placed near cancerous cells
• side effects of radiotherapy

  • sickness
  • fatigue
  • damage to other cells
• medical tracer

  • help diagnose medical issues by tracking / locating tumours
  • short half life / decay quickly / minimises time patient is exposed to radiation
• PET scans

  • positron emission tomography
  • radioactive isotope injected into patients bloodstream
  • emits gamma radiation
  • move to the highest metabolic area (most blood / usually a tumour)
  • patient lies in scanner
  • can see where the tracer is concentrated
  • help diagnose medical conditions
• nuclear fission

  • 1 unstable large nucleus splits into 2 smaller nuclei
  • releases energy
  • used in nuclear power stations
  • hard to dispose of radioactive waste
• nuclear fusion

  • 2 smaller nuclei fuse into 1 large nucleus
  • emits a lot of energy as electromagnetic radiation
  • happens in stars
  • no radioactive waste
  • cannot be controlled and used for energy yet
• nuclear reactor

  • boron control rods - absorb neutrons to slow chain reaction
  • very thick concrete walls - stop gamma radiation leaving reactor
• nuclear power - positives

  • reliable and produces a lot of energy
  • doesn't produce CO2
  • uranium is in large supply
• nuclear power - negative

  • very expensive to build
  • only last 30 - 40 years
  • challengedisposing of radioactives of waste
  • risk of catastrophe
• nuclear fission - chain reaction

  • neutron fired at an unstable nucleus
  • splits apart
  • emits a large amount of energy as radiation
  • creates 2 daughter nuclei and 2/3 neutrons
  • neutrons absorbed by other unstable nuclei
  • repeats the process
• nuclear power - generates electricity

  • unstable nuclei splits
  • gamma radiation is emitted
  • radiation used to heat water
  • water turns into steam
  • turns a turbine
  • kinetic energy of the turbine turned into electrical energy by generator