Across
- 2. The body's ability to maintain a stable internal environment
- 3. Chemical messengers produced by the endocrine system
- 4. A substance that donates hydrogen ions in solution
- 8. The force that pulls objects toward Earth
- 9. The amount of substance containing 6.02 × 10²³ particles
- 10. The body system that fights diseases
- 12. The bending of light as it passes between materials
- 14. The tendency of an object to resist changes in motion
- 15. The process of breaking food into smaller molecules that can be absorbed
- 18. The force that opposes motion between surfaces
- 19. Newton's Third Law states that every action has an equal and opposite _____
Down
- 1. The process by which oxygen enters the blood and carbon dioxide leaves it
- 5. The distance between two identical points on a wave
- 6. The smallest unit of an element that retains its properties
- 7. The rate at which velocity changes
- 11. The spreading of waves after passing through a gap or around an obstacle
- 13. The bouncing of a wave off a surface
- 16. An atom of the same element with a different number of neutrons
- 17. The number of waves passing a point each second