Chapter 8 States of Matter Objective: Describe three states of matter. The states of matter are the physical forms in which a substance can exist. Matter is made up of tiny particles called atoms and molecules. These particles are always in motion and are always bumping into one another There Are Three states of matter: 1. A solid is the state of matter that has a definite shape and volume The particles in a solid do not move fast enough to overcome the attraction between them. Each particle vibrates in place and is locked in place by the particles around it. There Are Two Kinds of Solids: 1. Crystalline solids have a very orderly, three-dimensional arrangement of particles. 2. Amorphous solids are made of particles that do not have a special arrangement. 2. Liquid is the state of matter that has a definite volume and but takes the shape of its container. The particles of a liquid move fast enough to overcome some of the attraction between them. So, the particles in a liquid slide past each other. Liquids have two special properties: Surface tension is a force that acts on the particles at the surface of a liquid. Viscosity is a liquid s resistance to flow. 3. Gas is the state of matter that has no definite shape or volume. The particles of a gas move quickly and can break away completely from one another. The amount of empty space between gas particles can change. Objective: Describe how energy is involved in changes of state. A change of state is the change of a substance from one physical form to another. Changes of State: 1. Solid to Liquid 2. Liquid to Solid 3. Liquid to Gas 4. Gas to Liquid 5. Solid to Gas 1. Melting is the change of state from a solid to a liquid. The temperature a solid changes to a liquid is its melting point. Adding energy to a substance during a change of state is called an endothermic change. 2. Freezing is the change of state from a liquid to a solid. The temperature a liquid changes to a solid is its freezing point. Removing energy to a substance during a change of state is called an exothermic change. 3. Evaporation is the change of state from a liquid to gas. Evaporation occurs at the surface of a liquid that is below its boiling point. Boiling is the change of a liquid to a gas throughout the liquid. The temperature a liquid boils is its boiling point. 4. Condensation is the change of state from a gas to a liquid. The condensation point is the temperature a gas becomes a liquid. 5. Sublimation is the change of state where a solid changes directly into a gas. Objective: Identify the two changes that can happen when a substance loses or gains energy. When most substances lose or gain energy, one of two things happen to the substance: temperature changes or state changes. But the temperature of a substance does not change during the change of state.