Across
- 6. The heavy, very dense and positive centre of an atom
- 9. Unwanted presence of radioactive atoms
- 10. Number of protons and neutrons
- 11. Unit measuring dose of radiation
- 15. Negative charge which orbits the nucleus
- 16. Constant low level environmental radiation
- 17. The time taken to lose half of its initial radioactivity
- 19. Medium ionising power
Down
- 1. One large unstable nucleus splits to make two smaller nuclei
- 2. Person is exposed to a radioactive source
- 3. Weak ionising power
- 4. Positive charge found in the nucleus
- 5. Very strong ionising power
- 7. Number of protons
- 8. Unit for radioactive decay
- 12. Two small nuclei join to make one larger nucleus
- 13. Unequal number of electrons to protons
- 14. Suggested idea of atoms as small as spheres that cannot be cut
- 18. Same number of protons and electrons