Radioactivity Its a Natural

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Across
  1. 3. has promethium-147 inside of it
  2. 5. radium ______ in the dark
  3. 7. has thorium-229 inside of it
  4. 8. odorless colorless gas
  5. 12. 26 millirems per year
  6. 13. the release of particles and energy together
  7. 16. Marie Curie discovered _______ and polonium
  8. 19. the electromagnetic _________ encompasses radio waves
  9. 20. Henri Becquerel discovered this
Down
  1. 1. radiation from outer space
  2. 2. a general term for any type of energy that emanates or radiates outward in all directions
  3. 4. most familiar form of radiation is _______ energy
  4. 6. electromagnetic energy is given off by this
  5. 9. Aluminum foil stops what kind of emissions
  6. 10. bananas, brazil nuts, peanuts, potatoes, and flour are all examples of _______
  7. 11. is inside cinder blocks and granite blocks
  8. 14. ___ 14 is what scientists use as means of estimating the age of remains
  9. 15. _____ particles- helium =4 nuclei
  10. 17. tells you if you have radon inside of your house
  11. 18. this type of radiation is dangerous because it has a lot of energy