Physics D

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Across
  1. 3. Subatomic particle that has a negative charge
  2. 7. Unstable atoms (radioisotopes) emit radiation to become stable
  3. 10. Different forms of an element with the same number of protons but different number of electrons
  4. 11. the process of exposing an object to nuclear radiation
  5. 12. very dense and positive centre of an atom
  6. 13. Number of protons
  7. 17. A particle that has the same number of protons and electrons
  8. 18. Emits a electron
Down
  1. 1. Subatomic particle that has a positive charge
  2. 2. What is radiation measured in
  3. 4. Number of protons and neutrons
  4. 5. What is used to measure radiation
  5. 6. What a unstable radioactive substance decays
  6. 8. The unwanted presence of materials containing radioactive atoms on other materials
  7. 9. A particle that has a uneven amount of electrons and protons
  8. 13. emits a helium nucleus
  9. 14. Subatomic particle that has no charge
  10. 15. Emits a electromagnetic wave
  11. 16. time taken for half the active nuclei in a sample to decay