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