The Periodic Table

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Across
  1. 2. The rusted, orange version of gold
  2. 4. ______ chloride
  3. 5. The protein in your teeth
  4. 7. A silvery gray metal that has a planet named after it
  5. 8. The substance you always need from your food
  6. 10. A lustrous metal found in Earth's crust
  7. 12. Fills up birthday balloons
  8. 15. Trees take this gas in to help us breathe
  9. 17. What they add to salt
  10. 19. Makes up the substance that entinguishes fire
  11. 20. One step below gold
Down
  1. 1. What comes before "foil" on your box of foil
  2. 3. You need it to breathe
  3. 6. Pencil substance was once toxic
  4. 9. The softest lanthanide
  5. 11. The substance in pools that stings your eyes
  6. 13. Tuna are dying from the ______ in their blood
  7. 14. What the bars in the Treasury are made of
  8. 16. Atomic number 7
  9. 18. The best material to use for a safe