Physics: section 7 - radioactivity and particles

Radioactivity
1. At the centre of every atom is a nucleus
  1. The nucleus contains protons and neutrons
  2. Electrons are negatively charged
  3. The number of protons in the nucleus is called the atomic number
  4. The total number of protons and electrons in the nucleus is called the mass number
2. Isotopes are Atoms with different numbers of neutrons
  1. Most elements have a range of isotopes
  2. Isotopes have the same number of protons, but a different number of neutrons
  3. Each element only has 1 or 2 stable isotopes, all the others tend to be unstable and therefore can be radioactive as it decays
3. Radioactive decay is random
  1. The nuclei of unstable isotopes break down at random
  2. Each nucleus decays spontaneously, it completely unaffected by physical conditions such as temperature
  3. When the nucleus decays it spits out one or more types of radiation: Alpha, Beta and Gamma
  4. In this process, the nucleus often changes into a new element
4. Background radiation is everywhere all the time
  1. Some radioactivity comes from the air, food, building materials, soil rocks . . .
  2. Comes from radiation from space (cosmic rays) which are mostly from the sun
  3. Some from all living things
  4. Human activity such as nuclear explosions contribute to the total
The three kinds of radioactivity
Alpha scattering and nuclear equations
Half-life
Uses of nuclear radiatiion
Risks from nuclear radiation
Nuclear fission
Revision questions for section 7
1. 1. List the 3 particles which make up an atom
2. 2. What is the isotonic number of a nucleus ?
3. 3. What is the mass number of a nucleus ?
4. 4. What are isotopes of an element ?
5. 5. Where does background radiation come from ?
6. 6. Give 2 ways you can detect ionising radiation
7. 7. Describe what Alpha, Beta and Gamma radiation are
8. 8. Which is the most ionising type of radiation ?
9. 9. What type of radiation is stopped by paper ?
10. 10. What is the half life of an element ?
11. 11. Describe 3 uses of nuclear radiaition
12. 12. Why is radiation dangerous to living organisms ?
13. 13. Why is radioactive decay hard to get rid of ?
14. 14. What are the products of the nuclear fission of Uranium-235 ?
15. 15. Describe how a chain reaction is set up in a nuclear reactor ?
16. 16. What job do control rods and moderators do in a nuclear reactor ?

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Physics: section 7 - radioactivity and particles

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