Unit 2 Notes: Kinetic Molecular Theory

(1) The Kinetic Molecular Theory Particles are in constant, random motion, resulting from their collisions with each other and surfaces. Increase Heat Energy of Particles: Increase amount of collisions Increase amount of motion + speed Decrease Heat Energy of Particles: Decrease amount of collisions Decrease amount of motion + speed

(2) EXAMPLE #1: We saw this happen with the food coloring and the beakers of water… Cold Water: Hot Water:

(3) Phases of Matter Solid: Liquid: Has a uniform and organized structure. Maintains shape. Particles barely move. Liquid: Does not have a uniform or organized structure. Only maintains shape inside a container. Particles are free to flow and move in random directions. Gas: No shape. Particles are spread out and move in random directions.

(4) EXAMPLE #2: Let’s draw pictures to compare Solids to Liquids to Gases: Solid: Liquid: Gas:

(5) Changing Phases In order for a substance to “change phase”, it must either LOSE or GAIN heat energy. Solid  Liquid  Gas: Particles must GAIN heat energy Particles move more, spread out more, and break structure Gas  Liquid  Solid: Particles must LOSE heat energy Particles slow down, get close together, and align to structure

(6) EXAMPLE #3: Let’s think about what happens when ICE MELTS…

(7) EXAMPLE #4: Let’s think about what happens when you boil water…

(8) Types of Phase Changes: Melting = Changing from Solid to Liquid Freezing = Changing from Liquid to Solid Evaporation = Changing from Liquid to Gas Condensation = Changing from Gas to Liquid

(9) EXAMPLE #5: Let’s think about what happens when shower steam CONDENSES on the bathroom mirror…

(10) EXAMPLE #6: Let’s think about what happens when you make ice cubes…