Atomic Structure & Periodic Table

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Across
  1. 4. an atom with the same number of protons, but different atomic mass
  2. 9. subatomic particle with a negative charge
  3. 10. center of an atom; contains protons and neutrons
  4. 11. groups of elements with similar characteristics
  5. 13. the mass of protons and neutrons
  6. 18. not very conductive, usually gases
  7. 19. the number of protons in an atom
  8. 22. particles smaller than an atom
  9. 23. family with one valence electron; very reactive
  10. 24. columns of the periodic table
  11. 25. a positively charged ion
Down
  1. 1. rows of the periodic table
  2. 2. family with seven valence electrons; very reactive
  3. 3. subatomic particle with a positive charge
  4. 5. subatomic particle with a neutral charge
  5. 6. family with a full outer shell
  6. 7. chart to organize elements
  7. 8. family with two valence electrons; not as reactive
  8. 12. from left to right, the number of protons increases
  9. 14. an atom that has lost or gained an electron
  10. 15. type of electrons found in outer shell
  11. 16. a negatively charged ion
  12. 17. very conductive, opaque, usually lustrous
  13. 20. substances with qualities of both metals and nonmetals
  14. 21. most basic unit of an element