crossword puzzle nuclear

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Across
  1. 3. rays of energy
  2. 4. splitting a nuclei
  3. 5. 2/4
  4. 7. the number of protons and neutrons combined
  5. 10. the emitting of radiation
  6. 11. half of the lifespan of a element
Down
  1. 1. neutral charge
  2. 2. combining two nuclei
  3. 5. the number of protons
  4. 6. 0/-1
  5. 8. positive charge
  6. 9. the center of a atom