Radiation Crossword

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Across
  1. 1. Helium nuclei containing two protons and neutrons
  2. 4. The protons and neutrons in an atom that don't hold together are strongly are ________
  3. 5. Penetrates human skin and can damage human tissue
  4. 7. Protons and _________ make up the nucleus
  5. 8. Has the same number of protons but different number of neutrons
Down
  1. 2. Sub-atomic particle that has a positive charge
  2. 3. Travels at the speed of light and are highly penetrating
  3. 6. Sub-atomic particle that has a negative charge