Across
- 5. The particles in the nucleus
- 6. The minimum size needed for a chain reaction
- 10. holds together protons and neutrons
- 14. fusion caused by high temperatures
- 16. Building blocks of the universe
- 18. The average mass of all the isotopes of an element
- 19. In the smallest possible units
- 20. Neutral particles in an atom
Down
- 1. Electromagnetic radiation from radioactive nuclei
- 2. The time it takes for half a sample to decay
- 3. The nucleus of a helium atom
- 4. Small, negative particles in an atom
- 7. When an element decays into another element
- 8. Positively charged particles of an atom
- 9. When a reaction causes another reaction
- 11. The splitting of two nuclei into smaller halves
- 12. An electron ejected from a radioactive nucleus
- 13. Number of protons and neutrons in an isotope
- 15. Amount of protons in an element
- 17. The same element with a different number of neutrons