States of Matter Solids, Liquids, and Gases

C. T., E. T.

Liquids Liquids are a type of fluid with: a constant volume particles that are farther apart molecules flow past each other the ability to take the shape of their container, but not its size flows in all directions when pressure is applied The thermal energy is great enough to overcome intermolecular forces. (ex. water, oil, juice) Liquids are classified by viscosity - the resistance to flow.

Gases Gases are a type of fluid with: particles that are free particles that have more energy fast-moving particles the ability to fill their container Thermal energy overcomes intermolecular forces. (ex. air, helium, gasoline)

Melting and Boiling Points The melting point is the temperature at which a substance changes from a solid to liquid. (ex. The melting point of water is 0 degrees Celsius or 32 degrees Fahrenheit) The boiling point is the temperature a which a liquid becomes a gas. (ex. The boiling point of water is 100 degrees Celsius or 212 degrees Fahrenheit)

Pressure Pressure is when a force is applied to a fluid When pressure is applied to a balloon full of gas, it expands sideways, but when pressure is applied to a bowling ball, it stays the same Pressure is caused by the collision of atoms

Intermolecular Forces Intermolecular forces are the forces between separate atoms. At longer distances, it’s force is attractive but weak. At close distances, its force is repulsive but strong.

Evaporation and Condensation Evaporation is the change from liquid to gas at a temperature below the boiling point Evaporation takes energy away from liquid because the molecules that escape are the ones with the most energy (ex. Your body sweats and evaporation of the sweat cools your body by carrying away energy) Condensation is the change from gas to liquid at a temperature below the boiling point Evaporation adds water to the air, and condensation takes it away If evaporation and condensation exactly balanced is saturated

Convection Convection is the transfer of heat through the motion of fluids When you place a pot of water on the stove, the hot water floats and the cooler water sinks. This is called natural convection Forced convection is caused when one object produces heat while something else distributes it. (ex. A boiler makes the heat, but the pumps distribute it)

Solids are a type of matter with: particles close together atoms that vibrate in place the ability to hold its shape when force is applied definite volume The atoms in solids are bound closely together because thermal energy is not enough to overcome intermolecular forces (ex. table, brick, books)

Important mechanical properties of solids are: density: mass per unit volume strength: the ability to maintain shape under applying force elasticity: the ability to stretch and return to its shape ductility: the ability to bend without breaking brittleness: the tendency to crack or break under the application of force

Heat Conduction in Solids Heat conduction is the transfer of heat by direct contact (ex. When holding a warm cup in your hand, heat is conducted to your hand from the cup) If you place a spoon in the cup, the molecules will collide with each other. The hotter material will lose energy, while the cooler material will gain energy. Eventually, they reach thermal equilibrium, when their temperatures are equal.

Thermal Conductors and Insulators Solids make the best conductors because the atoms are so closely packed Thermal conductors are items that easily conduct heat (poor insulators)The words conductor and insulator describe a material’s ability to conduct electrical currents (ex. some thermal conductors are silver, copper, gold, aluminum) Conduction cannot occur in vacuum spaces where there is no matter