Nuclear Physics Words

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Across
  1. 1. The splitting of uranium-238 into to smaller atoms and a few neutrons
  2. 7. The substance in a nuclear reactor which slows down neutrons and makes them more likely to hit other uranium nuclei.
  3. 8. When a neutron from one fission reaction goes on to hit another uranium nucleus and cause it to split (and so on)
  4. 10. A piece of apparatus for detecting ionising radiation
  5. 13. The very tiny middle part of the atom which contains protons and neutrons (except for hydrogen which just has 1 proton)
  6. 15. A nucleus with electrons orbiting, with no overall charge
  7. 16. A positively charged particle
  8. 17. An uncharged particle (about the same mass as a proton)
  9. 18. The number of protons AND neutrons added together in an atom. The top number when you write an element in symbol form
Down
  1. 2. What is given off by radioactive atoms, and which causes ionisation (the knocking out of electrons from other matter)
  2. 3. Rods which are lowered into a nuclear reactor to slow the reaction down
  3. 4. The time it takes for the activity to fall to half of its original value (and therefore also the number of radioactive atoms to halve)
  4. 5. A radioactive isotope which is used to follow the path of the flow of a liquid or gas
  5. 6. Different forms of the same element, which have the same number of protons but different numbers of neutrons
  6. 9. The number of protons in an atom, and its position in the Periodic Table. The bottom number when you write an element in symbol form
  7. 11. Unstable
  8. 12. A negatively charged particle
  9. 14. A particle in the nucleus (i.e. a proton or a neutron)
  10. 19. The amount of ionising radiation emitted per second, measured in becquerels (Bq), so 1 Bq is one bit of radiation per second.