Across
- 2. elements that arent known
- 4. to the far right
- 5. atoms are packed tightly
- 7. its symbol is an HE
- 9. chemical element that forms a simple substance
- 12. number of protons and electrons
- 13. is needed to breathe
- 15. ments
- 17. the brain of a cell
- 18. its symbol is C
- 19. can be determined using atomic number
Down
- 1. same number as the atomic number
- 3. atoms move around alot
- 6. atoms move around smoothly
- 8. makes up anything with mass
- 9. to the left
- 10. Its symbol is B
- 11. universal colvent
- 14. its symbol is an H
- 16. neutral