Chemistry Crossword

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Across
  1. 8. / In the outside electron ring
  2. 12. / The smallest discrete particle
  3. 13. / A bond of opposite charged ions
  4. 16. / Gas starts to form
  5. 18. / More than one type of particle
  6. 19. / A 2-D model
  7. 20. / Harms plants and animals
Down
  1. 1. / To Burn in air
  2. 2. / Atoms sharing electrons
  3. 3. / Shiny, hard and ductile
  4. 4. / Charged atom or molecule
  5. 5. / A organizing system
  6. 6. / Negatively charged particle
  7. 7. / Computer generated model
  8. 9. / Centre of an atom
  9. 10. / A horizontal row on the PT
  10. 11. / A vertical column on the PT
  11. 14. / Ability to dissolve in another
  12. 15. / Has mass and takes up space
  13. 17. / Positively charged particle