1. Gas - a substance that is characterised by widely separated molecules in rapid motion Mixtures of gases are uniform. Gases will expand to fill containers.

2. n Common gases include - O 2 and N 2, the major components of "air" n Other common gases - F 2, Cl 2, H 2, He, and N 2 O (laughing gas)

3. Kinetic Theory A gas consists of small particles that move randomly with rapid velocities The attractive forces between the particles are negligible The actual volue occupied by gas molecules is extremely small cmpaired to the volume that a gas occupies

4. Kinetic Theory cont. The average kinetic energy of gas molecules is proportional to the Kelvin temperature Gas particles are in constant motion, moving rapidly in straight paths.

5. Kinetic energy of particles

6. Properties that describe a gas PropertyDescriptionUnits of Measurement *top used in calculations Pressure (P)The force exerted by gas against the walls of a container Atmosphere (atm)* mm Hg Volume (V)The space occupied by the gasLiter (L)* Temperature (T)Determines the kinetic energy and rate of motion of the gas particles Kelvin (K)* Celsius ( o C) Amount (n)The quantity of gas present in a container Moles (n)* Grams (g)

7. Pressure Force exerted over an area. Air pressure is always exerting force on us and all around us!

9. How do they all relate?

10. Combined Gas Law

11. All put together!