P3 – Radioactive Materials

1. P3 – Radioactive Materials

2. Radioactive Elements • Some elements emit ionising radiation all the time and are called radioactive • Radioactive elements are naturally found in the environment, emitting background radiation

3. The Atom • Electrons, Protons, Neutrons and the Nucleus are all parts of an atom • The Nucleus, made of Protons and Neutrons

4. Isotopes • Every atom of any element has the same number of protons but the number of neutrons may differ • The same element with different numbers of neutrons is called an isotope • These 3 atoms are all isotopes of Hydrogen:

5. The Nucleus is the only thing involved in Radioactive Substances • Radioactive Materials are unchanged by: • Chemical reactions (only electrons involved in these) • Changes of state (Solid, Liquid, Gas) • Crushing

6. 3 Types of Radiation • Alpha: • 2 Protons + 2 Neutrons • Beta: • 1 Electron • Gamma: • High energy wave

7. An unstable nucleus will emit radiation to become more a more stable nucleus

8. Half-Life • Overtime, the Activity of Radioactive Sources Decrease • Half-Life: The time it takes for the number of unstable atoms in a sample to halve. • Carry out simple calculations

9. Ionising Radiation • Ionising Radiation removes electrons from atoms creating Ions (Charged atoms). These can then take part in other chemical reactions

10. When ionising radiation strikes living cells these may be killed or may become cancerous

11. Helpful Ionising Radiation • Ionising Radiation can be used to: • sterilise surgical instruments • sterilise food • treat cancer

13. Electricity • Electricity is a secondary energy source. • This means that we get electricity from the conversion of other sources of energy, such as coal, nuclear, wind or solar energy. • These are called primary sources.

14. Electricity = Convenient • Electricity is convenient because it is easily transmitted over distances and can be used in many ways

15. Making Electricity • Coal is burnt to heat water to make steam • The steam turns the turbine • Turbine turns a generator which produces electricity • Electricity goes to the transformers to produce the correct voltage

16. Efficiency • Light bulbs are only 10% efficient. 90% of the energy provided to them is lost as heat You need to know how to read these diagrams

17. Renewable Energy • Recall two examples: • Solar panels • Wind turbines • Geothermal • Hydroelectricity

18. Power stations which burn carbon fuels (fossil fuels) produce carbon dioxide

19. Nuclear Fuel / Nuclear Fission • Changes in the nucleus creates lots of energy • Nuclear Fission:a neutron splits a large and unstable nucleus (Uranium) into two smaller parts, roughly equal in size, releasing more neutrons

20. Nuclear Energy • The amount of energy contained in nuclear fuel is millions of times the amount of energy contained in a similar mass of chemical fuel such as coal, making nuclear fission a very tempting source of energy.

21. Nuclear Fission creates a chain reaction and these can be dangerous unless they are controlled

22. Controlling Fission • Fission heats the coolant which is used for steam • Control rods absorb neutrons • These can be moved up and down to control the amount of neutrons escaping the fuel rods

23. Radioactive Waste • Is categorised into 3 parts and this relates to it’s disposal methods • high • intermediate • low