Across
- 4. a process in which neutrons released in fission produce an additional fission
- 9. the total number of protons and neutron in an atom
- 10. subatomic particle with a positive electrical charge
- 12. amount of time that passes for half of an atom to decay
- 13. a layer of aluminum stops this
- 14. a subatomic particle without a electric charge
Down
- 1. the number of a chemical element in the periodic system
- 2. cannot go through human skin
- 3. cannot go through lead
- 5. this is radioactivity from the sun's heat
- 6. dividing of the nucleus
- 7. equal number of protons but a different number of neutrons
- 8. the act of emitting radiation spontaneously
- 11. the center of an atom