Across
- 3. A table of the chemical elements arranged by atomic number
- 5. The speed of something in a given direction
- 8. The envelope of gases surrounding the Earth or another planet
- 12. Freedom from the control or influence of others
- 15. A group of stars forming a recognizable pattern
- 16. First U.S. President and a state on the West Coast
- 17. The Unit of pressure
- 18. Process plants use to convert sunlight into food
- 19. The hard white outer covering of a tooth
Down
- 1. The Renaissance artist and inventor of the "Mona Lisa"
- 2. Even light cannot escape it
- 4. A proposed explanation for a phenomenon, used as a starting point for investigation
- 6. Cold-blooded vertebrate that lives on land and in water
- 7. The last active ruler of the Ptolemaic Kingdom of Egypt
- 8. He is also famous for exclaiming "Eureka!"
- 9. The scientific study of life and living organisms
- 10. The world's highest mountain range, home to Mount Everest
- 11. A system of government by the whole population, typically through elected representatives
- 13. A biological community of interacting organisms and their physical environment
- 14. An animal lacking a backbone