cruciverba science

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