Element Crossword Puzzle

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Across
  1. 2. 20 neutrons, 20 protons
  2. 4. alkaline earth metal, period 3
  3. 8. group 11, 118 neutrons
  4. 9. atomic mass of 261, group 4
  5. 11. period 5, group 9
  6. 12. halogen, 53 electrons
  7. 13. noble gas, 10 neutrons
  8. 14. transition metal, 39 protons
Down
  1. 1. alkali metal, period 4
  2. 3. metal, 29 electrons
  3. 5. metalloid, 14 neutrons
  4. 6. nonmetal, group 1
  5. 7. nonmetal, 7 neutrons
  6. 10. noble gas, 2 electrons
  7. 15. atomic number of 86, period 6