Chapter 6: States of Matter

1. Chapter 6: States of Matter KMS 8th grade Science

2. Introduction to Chemistry • Chemistry – • Matter - The study of the properties of matter and how matter changes Anything that has mass and takes up space (that space is volume)

3. Lesson 1 – Solids, Liquids and Gases • What types of matter do you see in this picture? Air (gas) Bubbles (liquid) Water (liquid) metal sign (solid)

4. Most Common Phases of Matter • Solid • Liquid • Gas How can matter be described? State Texture Measurements (volume, mass, density) Color Odor

5. Solids • Matter that has definite shape and definite volume. • Arrangement of Particles: • How do these particles move? • Illustration of particle arrangement. Very close together Vibrate in place

6. Liquid • Matter that has no definite shape but has a definite volume. • Arrangement of Particles: • How do these particles move? • Illustration of particle arrangement. Further apart than particles in a solid (greater potential energy) More freely. Particles take shape of container.

7. Gas • Matter that has no definite shape or no definite volume. • Arrangement of Particles: • How do these particles move? • Illustration of particle arrangement. Large distance between particles. Greatest amount of potential energy. Quickly and freely.

8. Particle illustrations

9. When talking about liquids you should know… • Viscosity • The stronger the attraction between forces • Examples: High Viscosity vs. Low Viscosity • Surface tension A measurement of a liquids resistance to flow. the higher the viscosity Uneven forces acting on the particles on the surface of a liquid

10. When talking about gas you should know… • Vapor • Evaporation The gas state of a substance that is normally a solid or a liquid at room temperature. Vaporization that occurs only at the surface of a liquid.

11. Lesson 2: Changes in State What change of state are you observing? As a snowman melts you observe a solid turning into a liquid.

12. Changing an objects state • You can change an objects state of matter by adding or removing • When you add thermal energy: • When you remove thermal energy the opposite occurs: Particles slow down (kinetic energy decreases) or move closer together (decrease potential energy) or both. thermal energy The particles move faster (increased kinetic energy) or move farther apart (increased potential energy) or both.

13. Solid to Liquid or Liquid to Solid • Melting • Freezing To change matter from a solid to a liquid. Thermal energy must be added. To change matter from a liquid to a solid. Thermal energy must be removed.

14. During the solid phase • Temperature stops increasing when it reaches which is the temperature at which • The horizontal line indicates that • Once the phase change is complete • The reverse occurs when going from a liquid state to a solid state. temperature and thermal energy increase. melting point solid changes to liquid. temperature has stopped increasing but thermal energy continues to increase. thermal energy (PE) slows down and temperature (KE) begins to rise again.

15. Liquid to Gas or Gas to Liquid • Boiling • Condensation Vaporization that occurs throughout a liquid. Changes liquid to a gas. The change of state from a gas to a liquid. When vapor cools back to a liquid.

16. What is the main difference between evaporation and boiling? During evaporation a substance vaporizes only at the surface. During boiling a substance vaporizes at the surface but also within the liquid.

17. During the liquid phase • Temperature stops increasing when it reaches which is the temperature at which • The horizontal line indicates that • Once the phase change is complete temperature and thermal energy increase boiling point liquid changes to gas temperature (KE) has stopped increasing but thermal energy (PE) continues to increase. thermal energy (PE) slows down and temperature (KE) begins to rise again. The reverse occurs when going from a gas to a liquid

18. Is it possible for a solid to become a gas without becoming a liquid first? • YES! This is called • Sublimation • Deposition Sublimation The change of state from a solid to a gas without going through the liquid state The change of state of a gas to a solid without going through the liquid state.

19. Phase Changes

20. Energy can never be created or destroyed… for matter to change phases thermal energy is transferred.

21. Lesson 3: Behavior of Gases

22. Pressure and Volume • Pressure • Volume The amount of force applied per unit of area. The amount of space an object occupies.

23. Pressure and Volume • As volume pressure with the same number of particles. • Does the number of particles change from the first illustration to the last? • What is happening in the picture? decreases increases No, the number of particles remain the same. As the plunger moves down, pressure increases and volume decreases.

24. Boyle’s Law • Pressure of a gas increases if the volume decreases and pressure of a gas decreases if the volume increases when the temperature is constant. • Robert Boyle • Have your ears ever popped in an airplane or in the car? Use Boyle’s Law to explain how this happens. British scientist who was the first to describe the properties of gases. On the ground (at sea level) air pressure inside your ear and the pressure of the air surrounding your ear are equal. When you increase altitude air pressure surrounding your ear decreases while the pressure in your ear stays the same causing increase in volume. This causes the pain you feel.

25. Charles’s Law • The volume of a gas increases with increasing temperature, if the pressure is constant. • Jacque Charles • What happens to a full balloon if you take it outside on a cold winter day? French scientist who described the relationship between temperature and volume of gas. When the balloon is in the cold air, the temperature of the gas inside the balloon decreases, causing the particles to slow down and come close together. Fewer particles hit the inside of the balloon causing it to look deflated.