cruciverba science
Across
- 1. The central part of an atom where protons and neutrons are located.
- 5. Pertaining to the moon.
- 6. Atoms or molecules with a net electric charge.
- 10. Relating to the structure of the Earth's crust.
- 12. The largest planet in our solar system.
- 15. A preparation used to provide immunity against diseases.
- 17. A group of atoms bonded together.
- 18. Process by which plants make food using sunlight.
- 19. The study of living organisms.
- 20. Any individual living thing.
Down
- 2. The seventh planet from the sun.
- 3. A group of living organisms consisting of similar individuals.
- 4. The natural home of an organism.
- 7. A discrete amount of energy proportional in magnitude to the frequency of the radiation it represents.
- 8. When one celestial body moves into the shadow of another.
- 9. The distance between successive crests of a wave.
- 11. Earth's year-long elliptical orbit around the sun.
- 13. Relating to motion.
- 14. A system of millions or billions of stars, together with gas and dust.
- 16. The basic unit of a chemical element.