Physics D

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Across
  1. 3. radiation stopped by paper
  2. 4. radiation stopped by aluminium
  3. 6. contains neutrons and electrons
  4. 8. different forms of the same element
  5. 9. time taken to lose half of its radioactivity
  6. 14. constant low level environmental radiation
  7. 15. discovered electrons
  8. 16. person exposed to radiation
  9. 17. unwanted presence of radiation
  10. 19. negative charge
Down
  1. 1. discovered neutrons in the nucleus
  2. 2. said alpha particles deflected
  3. 5. unit measuring radiation
  4. 6. no charge
  5. 7. large, unstable nucleus that makes 2 smaller nuclei
  6. 10. same number of electrons and protons
  7. 11. 2 small nuclei join to make one large nucleus
  8. 12. radiation stopped by thick lead
  9. 13. positive charge
  10. 18. unequal number of electrons and protons