Periodic Table puzzle thingy

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Across
  1. 2. doesnt react to stuff bro
  2. 4. 38% denser than air, how does this help? argon crystals
  3. 5. it's phosphorus, another one i dont know
  4. 7. what a scandal!
  5. 10. the thing in balloons and stuff that makes your voice high pitched
  6. 11. ocean abundancy
  7. 12. moonshine.
  8. 15. cancer saver thingy
  9. 16. nickleback CD
  10. 19. iron man, what's the suit made out of?
  11. 20. in laptops, phones, etc.
  12. 21. Dmitri Mendelev
Down
  1. 1. stuff in protein shakes
  2. 3. if youve played BOTW, the big rock dudes
  3. 6. silver surfer but switch the surfer with this word
  4. 8. has magnet in the name
  5. 9. another one with no explination, Beryllium.
  6. 13. hard to find/identify and killed superman
  7. 14. it's Zinc bro, no idea what to say here
  8. 17. is similar to blue meth
  9. 18. captain americas shield material