chemistry research

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Across
  1. 2. wide spread occurrence in the Earth's crust
  2. 4. second most abundant element in the human body
  3. 7. the oldest known pills
  4. 9. one of the first mental to be used by humans
  5. 10. so dangerous the 19th century experimenter were deemed
  6. 12. table salt
  7. 13. found on the sun before earth
  8. 14. few elements that is liquid
  9. 16. it is the fifth most abundant chemical
Down
  1. 1. highest electrical conductivity
  2. 3. first metal to be worked by men
  3. 5. 24.305
  4. 6. main component of teeth and bones
  5. 8. First used a a weapon in world war 1
  6. 11. blood is red
  7. 15. formally used in self luminous paints for watches