Periodic table

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Across
  1. 2. Cu is the symbol for...
  2. 4. proton number is 22
  3. 7. has a atomic mass of 1.00784
  4. 8. Super man’s weakness
Down
  1. 1. is lighter then air
  2. 3. is what we breath
  3. 5. The first letters is one of the avengers
  4. 6. symbol on the periodic table is B