Radioactive decay

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  • Created by: Nadia
  • Created on: 22-12-12 14:52
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  • Radioactive Decay
    • Radioactive decay is an event governed by the laws of probability so it is random
    • the half-life: the length of time taken for half of the atoms in the sample to decay
      • constant for a particular event i.e. elementshave known half-lives
      • Half-lives vary between different radioactive elements from seconds to billions of years
    • A sample of isotope's activity can be plotted against time on a graph to measure the half-life.
      • this graph is called a radioactive decay graph
    • the unit for radioactive decay is the becquerel (Bq) which is radioactive decay per second
    • Carbon-14 is a 'naturally occuring radioactive isotope of carbon'.
      • it emits Beta particles and has a half-life of 5370 years
      • Organic objects can be dated (up to 60,000 years old) by measuring the proportion of carbon-14 to carbon-12
    • Alpha particles
      • helium nuclei so therefore have a charge of +2
      • can penetrate only a few cm in air but stopped by thin layer of skin
      • strong positive charge + high ionising power can cause a lot of biological damage once inside you
    • Beta Particles
      • made of electrons so charge of -1
      • can penetrate~15cm of air, several cm of flesh, few cm of aluminium/ perspex
      • can cause radiation burns
    • Gamma Radiation
      • uncharged eltromagnetic rays
      • can penetrate through material very easily and through several cm of lead
      • can cause radiation burns and may be delayed effects that develop e.g. cancer/ cataracts in the eye
    • characteristics of different forms of radiation mean they are useful for different purposes
      • e.g. medical uses like radio-imaging and  radiotherapy

Comments

Miss KHP


This is a great mind map! If you chose not to print it out, that's ok as you can test yourself afterwards by clicking the orange button. Minn maps are a great way to put information together- i.e. link things. Great for AQA especially.

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