Across
- 3. negative particle outside the nucleus
- 4. developed the first periodic table
- 9. good conductors of heat and electricity
- 11. also known as energy levels
- 12. nonreactive elements, group 18
- 14. negatively charged particles in the outermost energy levels of the electron cloud
- 16. positive particle in the nucleus
- 17. created the solid sphere model
- 18. neutral particle in the nucleus
- 19. the horizontal rows on the periodic table
- 21. the smallest particle of an element
- 22. gasses, or dull brittle solids
Down
- 1. atoms of the same element with different numbers of neutrons
- 2. the smallest particles that make up both protons and neutrons
- 5. dense center of an atom
- 6. discovered the number of protons is unique to each element
- 7. solids, semi-conductors
- 8. the first person to name an atom
- 10. space surrounding the nucleus
- 13. the vertical columns on the periodic table
- 15. most reactive metals, group 1
- 20. most reactive nonmetals, group 17