Unit 4 Section 2 Notes

1. Unit 4 Section 2 Notes Matter and Energy

2. Kinetic Theory of Matter: • Useful for seeingdifferences in the 3 common states of matter on earth: solid, liquid, and gas.

3. Kinetic Theory of Matter3 Main Points • All matter is made of atoms and molecules which act like tiny particles that are always in motion. • The higher the temperature, the faster the particles move. • At the same temperature, heavier particles move slower than lighter particles.

4. Kinetic Theory • Using the Kinetic Theory of matter, explain why a balloon filled with helium goes flat faster than one filled with regular air. • According to the Kinetic Theory, at the same temperature, heavier particles move slower than lighter particles. Since oxygen & carbon dioxide are more massive than helium, they don’t escape out of the tiny microscopic holes as fast as helium.

5. Solid • Solid: substances have a definite volumeand definite shape. • Substances have a fixed position; no freedom to change positions • Particles are held closely together by strong chemical attractions • Definite melting point

6. Solid • Diagram:

7. Liquid • Liquid: substances have a definite volume but no definite shape • particles are closely packed, but can still slide past each other • Take the shape of their container • Particles are close but not as close as a solid • Particles can move randomly and spread on their own

8. Liquid • Diagram:

9. Viscosity: • Viscosity: resistance of a fluid to flow • Determined by the attraction of particles: the stronger the attraction, the more viscous (thick) the liquid is. • Fluids with a high viscosity flow slowly, and fluids with a low viscosity flow quickly. • What is more viscous: apple juice or maple syrup?

10. Gas • Gas: particles do not have a definite volume or shape. • Particles are in a constant state of motion and rarely stick together • Expand to fill available spaces • Free to spread in all directions from areas of high concentration to areas of low concentrations. • Example: scents of food or perfume • Have a low density

11. Gas • Diagram:

13. Gas • Gases exert pressure • Pressure: force exerted per unit area of a substance • If there is too much pressure (too many helium particles) in a balloon, what happens? • A gas under pressure will escape the container if possible. Think about an air filled balloon that you let go.

14. Fluids • Fluids: substances that can spread • Both liquids and gases can spread, so they are considered fluids.

15. States of Matter Video • https://www.youtube.com/watch?v=KCL8zqjXbME

16. Plasma • Plasma: does not have a definite shape or volume; considered to have the properties of fluids. • Most common state of matter in universe, but noton Earth • Makes up 99.9 % of the universe • Plasma is superheated gas and is a collection of free moving electrons and ions • Conducts electricity

17. Plasma • Examples of natural plasma on earth: • lightning • fire • Aurora borealis • Artificial plasma on earth includes fluorescent lights

18. Energy • Energy: the ability to change or move matter • Examples of energy or sources of energy: • heat, light, spring coiling, batteries • Energy must be added or removed to cause a change in state.

19. Energy • Energy must be ADDED to melt or evaporate substances • Aluminum must be melted before it can be recycled • As aluminum particles gain heat, particles move faster and break away from fixed positions and become liquids: called melting

20. Energy • Energy must be RELEASED to make a gas become a liquid or solid again. • When H2O is a gas and molecules slow down the water vapor returns to a liquid (called condensation). When molecules slow down even more, the water goes to a solid (ice).

21. Energy • Energy relationship between solid, liquid, and gas diagram: liquid gas solid Energy ABSORBED Energy RELEASED

23. Important Note: • Changing the state of matter does NOT change the substance or mass. • Water, steam, and ice are all H2O: the only change is the nature of attraction between molecules

24. Phase Change Diagram: Solid Melting Sublimation Deposition Freezing Condensation Liquid Gas Vaporization

25. Phase Changes • Evaporation: change of a substance from a liquid to a gas. • Condensation: change of a substance from a gas to a liquid. • Sublimation: change of a substance from a solid to a gas. • Deposition: change of a substance from a gas to a solid • Example: Water vapor without becoming liquid- this is how snow forms in clouds.

26. Atoms are constantly in motion. • As the temperature of an object increases, • The vibrations of atoms increases • The spacing of atoms increases • So, the volume of matter expands when the spacing increases. • A temperature increase results in a volume increase.

28. Law of Conservation of Mass • Law of Conservation of Mass states that Mass cannot be created or destroyed. • Example: Burning a match: consider what you start and end with.

29. Trivia Question • Trivia Question: If mass cannot be created or destroyed, then why do we have to replace our tires when the rubber “wears away”?

30. Law of Conservation of Energy • Law of Conservation of Energy states that Energy cannot be created or destroyed. • Energy can be converted from one form to another. • Example: A wristwatch: from chemical energy to mechanical energy.