1. Chapter 7 Lesson 3

2. Physical Change A change in size, shape, form, or state of matter Matter’s identity stays the same Matter does not become something different

3. State of Matter Movement of particles must change Thermal energy (heat) is added or removed

4. Adding Thermal Energy Particles move faster Temperature increases Solid to Liquid Particles move too fast for attractive force to hold them together – reaches melting point Liquid to Gas Particles move too fast for attractive force to hold them together – reaches boiling point

5. Sublimation Solid changes directly into a gas without first being a liquid Example: dry ice (frozen carbon dioxide), solid iodine

6. Removing Thermal Energy Particles slow down Temperature decreases Gas to liquid Particles slow down enough for attractive forces to pull the particles close together – condensation Liquid to solid Particles slow down enough for attractive forces to pull the particles close together - freezing

7. Freezing and melting Reverse processes Occur at the same temperature Boiling and condensation Reverse processes Occur at the same temperature

8. Deposition Gas changes directly into a solid without first being a liquid Example: frost Opposite of sublimation

9. Dissolving Physical change because the identities of the substances have not changed Example: salt water Can be reversed by boiling

10. Conservation of Mass Mass is conserved because it remains the same after a change, such as a physical change The particles of matter that are present before a physical change are the same as those present after the physical change If a sample of water has a mass of 200 g and the final solution has a mass of 230 g, how much solute dissolved in the water?