Physics P6 Radioactive Materials

Radioactivity
1. Atoms consist of a Nucleus + Orbiting Electrons
  1. The nucleus contains protons and neutrons
    1. It takes up most of the mass of the atom
  2. The electrons are tiny
    1. They whizz around the outside of the atom
2. The number of Neutrons in an element ISN'T FIXED
  1. Every atom of a particular element has the same number of protons in its nucleus
    1. eg. Every carbon atom has 6 protons
    2. eg. Every nitrogen atom has 7 protons
  2. Usually each element only has one or two stable isotopes (Carbon-12)
3. Radioactive elements EMIT ionising radiation
  1. Some elements emit ionising radiation all the time
    1. These elements are radioactive
      1. Radioactive atoms are unstable
  2. When an atom decays, it spits out one or more of three types of ionising radiation
Radiation
1. Alpha
  1. Slow and Heavy
  2. Can be blocked by a piece of paper
2. Beta
  1. Lighter and MORE penetrating
  2. Are blocked by a thin layer of aluminium
3. Gamma
  1. Is an electromagnetic wave
  2. Blocked by thick lead
Half - Life
1. Is the time taken for half of the radioactive nuclei now present to decay
2. Initial count: 640 (/2) after ONE half life: 320 (/2) after TWO half lives: 160, etc..
The Atom and Nuclear Fusion
1. Nuclear fission releases a LOT of energy
  1. Splitting a gram of uranium releases over 10,000 times more energy than burning a gram of oil
2. Nuclear fission needs to be carefully controlled
  1. In nuclear reactors, a chain reaction is set up
Nuclear Fission and Nuclear Power
1. Nuclear power stations release energy by splitting atoms
  1. Nuclear fuel (uranium or plutonium) releases large amounts of energy when its nuclei split apart
2. The waste from nuclear power stations is hard to deal with
  1. The main problem with nuclear power is that it produces radioactive waste

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Physics P6 Radioactive Materials

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