Periodic Table

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Across
  1. 3. I react with strongly with water and have 55 protons
  2. 4. My atomic number is 78
  3. 6. Group with 7 valence electrons
  4. 8. I am not really an alkali metal, but since I have only 1 electron I behave like them
  5. 9. I am a Noble gas with an atomic weight of 222.018
  6. 11. I am a noble gas with 2 electrons
Down
  1. 1. I am a member of the Alkaline Earth Metals and I have a mass number of 40
  2. 2. I am a gas with a mass number of 19
  3. 5. I am a metalloid with an atomic number of 5
  4. 7. I have 26 Protons
  5. 10. I am a gas with 8 protons and 8 neutrons