### elastic collision

Collision between gas particles and between particles and container walls. These collisions have no net loss of kinetic energy

### fluid

Gas particles glide easily past one another. Both liquids and gases flow so they are both considered this. These take the shape of their container.

### real gas

A gas that does not behave completely according to the assumptions of the kinetic-molecular theory

### newton

It is the force that will increase the speed of one kilogram mass by one meter per second each second it is applied. It is the SI unit of force.

### standard temperature and pressure

For purposes of comparison, scientists have agreed on standard conditions of exactly 1 atm pressure and 0°C. These conditions are commonly abbreviated STP.

### Boyle's law

The volume of a fixed mass of gas varies inversely with the pressure at constant temperature. (simply - when volume goes up the pressure goes down, and when volume goes down the pressure goes up when temperature is kept constant)

### Charles's Law

The volume of a fixed mass at constant pressure varies directly with the Kelvin temperature (simply - when the temperature goes up the volume goes up, when the temperature goes down, the volume goes down if pressure is constant)

### combined gas law

Expresses the relationship between pressure, volume, and temperature of a fixed amount of gas.

### Dalton's Law of partial pressures

The total pressure of a mixture of gasses is equal to the sum of the partial pressures.

### gas laws

Simple mathematical relationships between the volume, temperature, pressure, and quantity of a gas.

### Gay-Lussac's Law

The pressure of a fixed mass of gas at constant volume varies directly with the Kelvin Temperature. (simply - pressure goes up with the temperature, and down with temperature if volume is kept constant)

### Avogadro's law

Equal volumes of gases at the same temperature and pressure contain equal numbers of molecules.

### Gay-Lussac's law of combining volumes of gases

At constant temperature and pressure, the volumes of gaseous reactants and products can be expressed as ratios of small whole numbers

### standard molar volume of a gas

The volume occupied by one mole of a gas at STP. This has been found to be 22.41410 L.

### ideal gas law

The mathematical relationship of pressure, volume, temperature, and the number of moles of a gas.

### evaporation

The process by which particles escape from the surface of a nonboiling liquid and enter the gas state.

### surface tension

A force that tends to pull adjacent parts of a liquid's surface together, thereby decreasing surface area to the smallest possible size.

### supercooled liquid

Substances that retain certain liquid properties even at temperatures at which they appear to be solid.

### crystal

A substance in which the particles are arranged in an orderly, geometric, repeating pattern.

### unit cell

The smallest portion of a crystal lattice that shows the three-dimensional pattern of the entire lattice.

### boiling

The conversion of a liquid to a vapor within the liquid as well as at its surface. It occurs when the equilibrium vapor pressure of the liquid equals the atmospheric pressure.

### boiling point

The temperature at which the equilibrium vapor pressure of the liquid equals the atmospheric pressure.

### critical pressure

The lowest pressure at which the substance can exist as a liquid at the critical temperature.

### equilibrium

A dynamic condition in which two opposing changes occur at equal rates in a closed system.

### equilibrium vapor pressure

The pressure exerted by a vapor in equilibrium with its corresponding liquid at a given temperature.

### Le Chatelier's principle

When a system at equilibrium is disturbed by application of a stress, it attains a new equilibrium position that minimizes the stress.

### Molar heat of fusion

The amount of heat energy required to melt one mole of solid at its melting point.

### molar heat of vaporization

The amount of heat energy needed to vaporize one mole of liquid at its boiling point.

### phase diagram

A graph of pressure versus temperature that shows the conditions under which the phases of as substance exist.

### triple point

Indicates the temperature and pressure conditions at which the solid, liquid, and vapor of the substance can coexist at equilibrium.