Across
- 1. chloropyll
- 3. hydrogen
- 4. helium
- 7. sodium
- 8. carbondioxide
- 11. sulfur
- 14. titanium
- 16. nitrogen
- 17. oxygen
- 18. lead
Down
- 1. calcium
- 2. phosphorous
- 5. gallium
- 6. magnesium
- 9. ecosystem
- 10. keratin
- 12. fiber
- 13. zinc
- 15. metallic
- 16. nitrate