Atoms

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Across
  1. 3. group of atoms together
  2. 5. number of protons
  3. 6. source of nuclear energy
  4. 7. positive
  5. 10. negative
Down
  1. 1. periodic table
  2. 2. mass number
  3. 4. atomic nucleus
  4. 8. neutral
  5. 9. two or more species of atom