chemistry puzzle

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Across
  1. 5. unreactive
  2. 8. a lightweight metal
  3. 11. a positive ion
  4. 13. group 1 metal
  5. 15. a bond formed by sharing electrons
  6. 17. tell you how many shells an atom has
  7. 18. contains (OH)- ions
  8. 19. join atoms together
  9. 21. left side of the periodic table
Down
  1. 1. gain of electrons
  2. 2. tells you about the properties of an element
  3. 3. part of a conductor in which electricity flows
  4. 4. a bond where there are delocalised electrons
  5. 6. loss of electrons
  6. 7. a type of distillation
  7. 9. a bond formed by donating electrons
  8. 10. dihydrogen oxide
  9. 12. neutalises an alkali
  10. 14. the molecular mass of a compound in grams
  11. 16. an ion that goes to the anode
  12. 20. where the electrons are