1. Changes of State

2. Is the change of a substance from one physical form to the other All changes of states are physical changes, this means that the identity of a substance does not change – Ex. Ice turns to water through melting. It is still made of the same thing.

3. Energy Particles of a substance have different amounts of energy when the substance is in different states. – Ex. Particles in Liquid water have more energy than particles in ice When a change of state happens, the energy of the particles of the substance changes too. So to change state you must add or remove energy

4. Melting Is the change of state from a solid to a liquid. You must add energy to a solid to increase the temperature. As it heats up the particles of the solid speed up. The temperature at which a substance changes from a solid to a liquid is the Melting point. Different substances have different melting points

5. Melting For a solid to melt, particles must overcome their attraction to each other. Melting is endothermic change because energy is gained by the substance as it changes.

6. Freezing Change of state from a liquid to a solid The temperature at which a liquid changes into a solid is the freezing point Freezing and melting happen at the same temperature To turn from a liquid to a solid the particles must overcome the motion particles

7. Freezing Freezing is an exothermic change because energy is removed from, or taken out of the substance as it changes

8. Vaporization Change of state from a liquid to a gas Two types of Vaporization Takes place throughout a liquid is called boiling The temperature at which a liquid boils is called the boiling point Evaporation occurs at the surface of a liquid below boiling point.

9. Condensation Change of state from a gas to a liquid Condensation point is the temperature at which a substance changes from a gas to a liquid.

10. Sublimation Change of state from a solid directly to a gas. Ex. Dry ice is colder than ice. Unlike ice, dry ice does not melt into a puddle of liquid.