Simple science crossword

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Across
  1. 7. maximum number of electrons 2nd shell can hold
  2. 9. Sun at the center
  3. 11. change that occurs in the inherited trait of a population over generations
  4. 12. Force that pulls an object toward earth
  5. 13. the densest element
  6. 15. Symbiosis when both organisms benefit each other
  7. 16. The process by which a liquid changes to a gas
  8. 17. Testable explanation for a problem
  9. 18. One of the first scientists to classify living things
  10. 19. death of an entire species
  11. 20. The center of an atom
Down
  1. 1. has only one proton
  2. 2. the process when an atom gains or loses an electron
  3. 3. the amount of matter in one unit volume
  4. 4. Separates visible light into different colors
  5. 5. smallest of the body's blood vessels
  6. 6. the study of the natural world through observation and investigation
  7. 7. A negatively charged particle found on the energy levels around the nucleus
  8. 8. evaporation from the leaves of plants
  9. 10. An area where particles in a medium are spaced close together
  10. 12. Shortest wavelength of the electromagnetic spectrum, treats some cancer
  11. 14. Opens and closes to control the size of the pupil, gives the eye color