Periodic Table Crossword

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Across
  1. 3. number of protons and neutrons in an atom
  2. 6. states that properties of elements change in a predictable way when arranged by atomic number
  3. 7. quantity equal to one-twelfth of a carbon-12 atom
  4. 9. elements in the break in period 6
  5. 11. reactive group 2 elements
  6. 14. elements that are good conductors of heat and electricity
  7. 15. semi-conducter used in computers
  8. 17. elements that are intermediate conductors of heat and electricity
  9. 18. reactive group 17 elements
  10. 19. reactive group 1 elements
Down
  1. 1. number of protons in an element
  2. 2. the heaviest noble gas
  3. 4. elements that are not good conductors of heat and electricity
  4. 5. average weight of all natural occurring isotopes of an atom
  5. 8. lightest noble gas
  6. 10. vertical column of elements on the periodic table
  7. 11. elements in the break in period 7
  8. 12. unreactive group 18 elements
  9. 13. metallic elements in groups 3-12
  10. 16. horizontal row of elements on the periodic table