States of Matter

 Solids have definite shape and definite volume  Particles in a solid are packed very closely together and are in a fixed position. This is what causes solids to have a definite shape and volume.

 Crystalline Solids:  Particles of a crystalline solid are found in regular, repeating patterns.  Melt at a specific temperature (melting point)  Examples  Salt, Sugar and Diamonds

 Amorphous Solids  Particles are not arranged in any regular pattern  Do not melt at any specific temperature  Examples  Plastics, rubber and glass

 Have a definite volume but no definite shape  Liquids take on the shape of container  Particles of a liquid are packed almost as tightly together as in a solid, but move around one another freely  Because these particles are free to move liquids have no definite shape

 Liquids are also called Fluids  Fluids: a substance that flows  *All liquids are fluid, but not all fluids are liquid

 Properties of Liquids  Surface Tension: is the result of inward pull among the molecules of a liquid.  Viscosity: a liquids resistance to flow

 Gas is a fluid  Gas can change volume very easily  As gas particles move they spread apart, filling the space available.  Gases have neither definite shape nor definite volume.

 Changes between Solid and Liquid  How does the state of matter of a substance relate to its thermal energy?  A substance changes state when its thermal energy increases or decreases sufficiently

 Melting is the change of state from a solid to a liquid.  Melting Point: is the specific temperature at which a substance melts.  Melting point is a physical property that scientists can use to identify an unknown substance.

 Change in state from a liquid to a solid  At its freezing temperature, the particles of liquid are moving so slowly that they begin to form regular patterns.

 Vaporization: change from a liquid to a gas  Vaporization takes place when the particles in a liquid gain enough energy to form a gas.  Evaporation: is vaporization that takes place only on the surface of a liquid

 Boiling : vaporization that occurs below the liquids surface as well as on the surface.  Boiling Point: temperature at which a liquid boils.

 Boiling Point and Air Pressure  The boiling point of a substance depends on the pressure of the air above it.  The higher the pressure the more energy required for substance to boil; more energy equals higher boiling point

 Condensation: is the opposite of vaporization  -change of state from a gas to a liquid  -occurs when a gas loses enough thermal energy to form a liquid

 Sublimation: occurs when particles of a solid do not pass through the liquid state as they form a gas.

 Measuring Gases  Volume: the amount of space the gas fills. Units: cubic centimeters, milliliters, liters.  Gas particles move and fill the space available in its container.

 Measuring Gases  Volume: the amount of space the gas fills. Units: cubic centimeters, milliliters, liters.  Temperature : is the measure of …..?  At room temperature particles of a gas travel about 500 m/s

 Pressure: is the force of the outward push divided by the area of the walls of the container.  Pressure = Force/Area  The firmness of an object comes from the pressure of the gas.

 Pressure and Volume  What happens when you block the end of the tube on a bicycle pump and then push down on the plunger?

 Boyle’s Law: relates the pressure of a gas and its volume.  Boyle found that when the pressure of a gas, at constant temperature, is increased the volume of the gas decreases. When pressure is decreased, the volume increases.

 Pressure and Temperature  When the temperature of a gas, at constant volume, is increased, the pressure of the gas increases.  When the temperature of a gas, at constant volume, is decreases, the pressure of the gas decreases.

 Volume and Temperature  Charles’s Law : Relates the volume with the temperature of a gas  Charles found that when the temperature of a gas is increase, at constant pressure, the volume of the gas also increases. If the temperature of a gas, at constant pressure, is decreased, the volume of the gas also decreases.

 Graph the data on pages 91 and 92 (figures 22 and 23)