Across
- 2. substance that cannot be broken down
- 5. a table in which elements are arranged
- 10. number of protons in an atom
- 12. good conductor of heat and electricity
- 13. smaller than a atom
- 14. a particle with no charge
Down
- 1. atoms of the same element with different amounts of nuetrons
- 3. smallest element particle
- 4. the outermost energy level
- 5. a positive charged particle
- 6. negatively charged particle
- 7. inert element in group 18
- 8. the sum of protons and nuetrons
- 9. middle of an atom
- 11. space taken up