Hunting the Elements!

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Across
  1. 1. can be used to repel sharks
  2. 5. used in the most powerful magnets
  3. 7. 3/4 of all the elements are ________________
  4. 9. when copper is combined with this other element it makes bronze
  5. 13. most people picture it as white and chalky but it's actually a shiny metal
  6. 15. the number of elements that exist in nature
  7. 18. negatively charged particles in an atom
  8. 19. these particles have no electrical charge
  9. 21. there are ________________ human-made elements on the periodic table
  10. 22. these elements are not actually rare but are essential for electronics
  11. 23. each element is _____________ and unlike any other
  12. 25. elements are the basic ______________ _____________ of the universe
  13. 27. symbols of the major elements in the human body
  14. 28. deadly gas or pool chemical?
Down
  1. 2. the number of protons gives an element its _____________ _______________
  2. 3. atoms with perfectly filled outer shells are ___________
  3. 4. what happens inside a nuclear reactor
  4. 6. metals are shiny materials that conduct _______________
  5. 8. all the gold ever mined would fit in a cube about this many feet wide
  6. 10. metal used in wiring and plumbing
  7. 11. mixing dangerous sodium and chlorine creates this common condiment
  8. 12. the number of ____________ determines which element an atom is
  9. 14. it is now possible to see atoms with a very powerful _________________
  10. 15. used in advertising signs
  11. 16. these elements on the far right of the periodic table do not react
  12. 17. wouldn't have batteries without it
  13. 20. light super-strong metal used in spyplanes
  14. 24. Fiestaware bowls from the 1930s contained this dangerously radioactive element!
  15. 26. Superman wouldn't like it...