Across
- 2. number of protons in the nucleus
- 5. least dangerous radiation
- 7. any of two or more forms of a chemical element
- 9. radiation that can be stopped with aluminum foil
- 10. splitting two heavy nuclei into lighter nuclei
- 12. the act of emitting radiation spontaneously
- 13. two light nuclei fusing together
Down
- 1. most harmful radiation
- 3. atoms that have an unstable charge
- 4. Neutral charge
- 6. time it takes for half of a substance to decay
- 8. positive charge
- 11. the sum of protons and neutrons