The Periodic Table

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Across
  1. 2. This is used in many pencils
  2. 4. This is used in fluoride toothpaste
  3. 7. This is what we breath in
  4. 9. This is used on some watches
  5. 11. We use this in some bracelet
  6. 14. By weight, 75% of the visible universe is this
  7. 15. We spend this at the store
  8. 17. This gas makes up 78% of the atmosphere
  9. 20. This is used in photographic flashes
Down
  1. 1. This is an invisible, radioactive gas
  2. 3. This used in keys and some expensive pens
  3. 5. Is incredibly useful in industry for wiring, heat sinks and coins
  4. 6. This highly poisonous
  5. 8. This is what we use every day
  6. 10. This killed soldiers in WWI
  7. 12. This is used in horseshoes
  8. 13. This what we use to make balloons float
  9. 16. This is superman's home planet
  10. 18. This what many people like and is used in some rings
  11. 19. People use this in their OPEN signs at the store