Periodic Table I

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Across
  1. 3. decays into radioactive polonium and alpha particles and can be used in cancer therapy
  2. 5. properties include: dull, low melting points, low density, brittle
  3. 9. determine the atomic number
  4. 10. used as the gas to fill filament light bulbs because it does not react with metals
  5. 12. this element is the only liquid transition metal
  6. 14. name for the horizontal rows on the periodic table
  7. 15. second group
  8. 17. first group
  9. 18. name for the vertical columns on the periodic table
Down
  1. 1. used as a filling gas for energy saving fluorescent lights and flash lamps
  2. 2. this element is the only liquid halogen
  3. 4. electrons in the outermost shell
  4. 6. all the noble gases have full __________
  5. 7. the number of noble gases
  6. 8. properties include: good insulator, shiny, high density, high melting point
  7. 11. colorless, odorless, and tasteless non-toxic gas that is used in balloons
  8. 13. 18th group
  9. 16. colorless and odorless, used to make high-voltage indicators, lightning arresters, diving equipment, and lasers