1.2 nuclear radiation
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- 1. Dr Pusey What do you think an atom is? Can you draw what it looks like?
- 2. TYPES OF RADIATION In a radioisotope (an isotope that decays) the nucleus is unstable and may spontaneously emit radiation to become more stable There are three different types of radiation: Alpha - Beta - Gamma This subject is covered in much greater detail in year 11 Physics!
- 3. ALPHA RADIATION Represented by the lowercase Greek letter alpha - Consists of 2 protons and 2 neutrons, it is a helium nucleus Positively charged (+2) Usually emitted by heavier elements such as uranium and radium Can be absorbed by a sheet of paper Range in air is only a few centimetres Emitted at a velocity of 5-7% the speed of light
- 4. BETA RADIATION Represented by the lowercase Greek letter beta - Consists of 1 electron Negatively charged (-1) Can be absorbed by 3.5 cm of lead or a sheet of aluminium Range in air is a few metres Emitted with a velocity of 30-90% speed of light
- 5. GAMMA RADIATION Gamma radiation = electromagnetic wave (not a particle) No charge, its a type of energy, not a particle Absorbed by several cm of lead Range in air is almost unlimited Electromagnetic wave, so it travels a the speed of light
- 6. HALF-LIFE Different radioisotopes decay at different rates Radioactive decay is a spontaneous process that cant be controlled Each radioisotope has its own characteristic decay rate (called half-life) The decay rate is unaffected by physical and chemical conditions (e.g. pressure, temperature) Half-life (1/2) = the time it takes for half the atoms in a sample to decay
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