Particle theory All matter is made up of very small particles. All particles in a pure substance are the same. There is space between the particles. The particles are always moving. The particles in a substance are attracted to each other. The strength of the attraction depends upon the type of particle.

Gases Particles not in any organized pattern Particles move freely and very quickly Can be compressed Takes up space and has weight Try's to take up all of the space available in container

Liquids Molecules not in a fixed order or location Molecules move freely, but slowly Cannot be compressed easily Can Flow Takes the shape of the container it is poured into

Liquids and Cohesion Molecules in matter are attracted to each other. Solid state has the highest level of cohesion. In a liquid state molecules want to be attached to each other. This is why we see water droplets trying to remain together.

Solid Particles in a fixed order and location Particles can only move in their fixed location (they vibrate) Cannot be compressed Cannot flow

Phase Changes of Matter

Water Phase Change Graph D 100 gas C Temperature º C. liquid B Pass out the Water Phase Change Graph blank to all students. As we work through the phase changes, please add to your graph. This is a graph that shows the energy and temperature changes as water turns from a solid, ice, to a liquid, water, and finally to a gas, water vapor. As we make additions on the board, you will make the additions to your paper. Mark the letters A, B, C, D and E. (click) First, we show that the molecules of water in the solid form are tightly packed and in a regular pattern forming crystals. We’ll take a closer look at the actual pattern later. Draw the crystal lattice here showing that water is a solid below zero degrees Celcius. (click) Next we show water molecules in the liquid state here between zero and 100 degrees Celcius. Draw the molecules a bit farther apart and without a crystal structure. (click) And here we have water in the gas state with the molecules farther apart A solid Time (minutes)

Time (minutes) E D 100 gas C liquid B A solid Temperature º C. As water changes from solid to liquid to gas, what is happening to the energy of the molecules? (increasing) (click) What is happening to the temperature? (increasing) A solid Time (minutes)

Time (minutes) condensing evaporating freezing melting E D 100 C B A Temperature º C. B freezing When the ice reaches zero degrees what starts happening? (melting from solid ice to liquid water) (click) If we were moving in the opposite direction, with decreasing energy and temperature, from liquid water to solid ice, what would that be called? (Freezing) (click) As the liquid water reaches 100 degrees, what happens? (change from liquid to gas, boiling) (click) If we were moving in the opposite direction, with decreasing energy and temperature, from water vapor to liquid water, what would that be called? (condensation, condensing) (click) Answer the questions of the bottom of your paper. melting A Time (minutes)

Changes of State (Phase Changes) – When matter changes from one state of matter to another. Melting (Solid to Liquid) Condensation (Gas to Liquid) Freezing (Liquid to Solid) Vaporization (Liquid to Gas) Sublimation (Solid to Gas) *Dry Ice-Solid CO2 Deposition (Gas to Solid) *Water Vapor to Ice – On windows in the winter.

Adding Energy Phase changes that require the addition of energy are called endothermic changes. (endo = inside, therm = heat) Which phase changes are endothermic? Melting (solid  liquid) Vaporization (liquid  gas) Sublimation (solid  gas)

Removing Energy Phase changes that require the removal of energy are called exothermic changes. (exo = outside, therm = heat) Which phase changes are exothermic? Freezing (liquid  solid) Condensation (gas  liquid) Deposition (reverse sublimation) (gas  solid)

Heat and Particle Theory Heat of fusion – The amount of energy required to turn a sample of solid matter into a liquid (ex. Ice to water) Heat of Vaporization – The amount of energy required to turn a sample of liquid matter into a gas

Temperature and Theory of Kinetic Energy Kinetic Energy – Energy produced by the constant motion and collision of particles of matter - Temperature – The measure of the amount of kinetic energy in matter How are Kinetic Energy and Temperature related?

Density of solids, liquids & Gases Does water as a liquid, water a solid, or water as a gas have the highest density? Explain.

Density Density can be described as the “crowdedness” of the particles that make up matter. When you describe something as being “heavy” or “light” you are referring to that something’s density. Each substance has its own, unique density. The closer the particles are together in a substance, the higher its density is.