CROSSWORD PUZZLE

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Across
  1. 2. building blocks of matter
  2. 3. is essentially a closed system
  3. 4. greek word "atmo" meaning "vapor or steam"
  4. 10. totality of all life form on Earth
  5. 11. smallest known particle
  6. 13. seperate the lowest layer and the second lowest layer of the atmosphere
  7. 14. subsystem that includes the rocks,soil, and ground
  8. 15. innermost layer of the Earth
  9. 16. outermost and thinnest layer of the Earth
  10. 18. negatively charged ion
Down
  1. 1. french astronomer and mathematician proposed this his theory on 1796
  2. 5. presence of clouds on this layer
  3. 6. postulated that the planets formed out of a nebula
  4. 7. contains man made satellite
  5. 8. a cloud of gas and dust in outer space
  6. 9. includes water that is on the surface of the planet, underground, and in the air
  7. 12. proposed the existence of the Kuiper Belt
  8. 15. positively charged ion
  9. 16. basic unit of life
  10. 17. discovered the mantle