Chapter 2 Solids, Liquids & Gases Solid-definite volume and shape Particles (atoms and molecules) are locked into position but vibrate.Particles (atoms and molecules) are locked into position but vibrate. Crystalline solids - salt, sand, sugar atoms and molecules are in a regular repeating pattern.Crystalline solids - salt, sand, sugar atoms and molecules are in a regular repeating pattern. Amorphous solid-atoms and molecules are not in a regular pattern (glass, plastic, rubber).Amorphous solid-atoms and molecules are not in a regular pattern (glass, plastic, rubber).

Liquids – no definite shape but have definite volume Takes the shape of its containerTakes the shape of its container Atoms and molecules are touching but can slide over each other.Atoms and molecules are touching but can slide over each other. Viscosity – resistance of a liquid to flowingViscosity – resistance of a liquid to flowing –Water has low viscosity –Molasses has high viscosity

Gases – no definite shape or volume Takes all available spaceTakes all available space Atoms and molecules are far apart and move around rapidly (500 m/sec)Atoms and molecules are far apart and move around rapidly (500 m/sec) Gases molecules bounce off each other and the walls of the container (this creates pressure).Gases molecules bounce off each other and the walls of the container (this creates pressure).

Pressure = force/area Tire pressure 32 lb/in 2 Atmospheric pressure 14.7 lb/in 2

Gas Laws Boyle’s Law – when pressure is increased the volume of a gas is decreased (at constant temperature). –Inversely proportional (when one goes up the other goes down) Examples: syringe, high altitude balloon List other relationships that are inversely proportional

Charles’s Law – when temp goes up volume increases. When temp goes down volume decreases (if pressure is kept constant). T V T V –Directly proportional – when one goes up, the other does too (they move the same direction). –List other relationships that are directly proportional

Charles Law Graph

The gas will have zero volume at -273 ˚C –This is the coldest possible temperature –It is called absolute zero (0 K) zero degrees Kelvin

CHANGES IN STATE (PHASE CHANGE) Solid LiquidGas Adding heat Removing heat

Adding heat (thermal energy) will change a solid to a liquid or a liquid to a gas Heat always goes from a warmer substance to a cooler substance. Heat is transferred by molecular vibration. The hotter something is the more the molecules vibrate.

Evaporation Melting Boiling Melting Boiling Solid Liquid Gas Solid Liquid Gas Freezing Condensation Freezing Condensation Sublimation – going from a solid to a gas without first changing to a liquid Materials can be identified by their boiling and melting points Sublimation (dry ice)