1. States of Matter

2. The Kinetic Molecular Theory
KMT – describes the behavior of gases in terms of particles in motion
Size:
Gas particles are small
Spaced very far apart
No significant attractive or repulsive forces between the gas particles

3. The Kinetic Molecular Theory
Motion:
Gas particles are in constant random motion
Kinetic energy is transferred when particles collide with each other or the sides of their container
The collisions are elastic (no energy is lost)

4. The Kinetic Molecular Theory
Energy:
Depends on the particles mass and velocity
KE = ½ mv2
Temperature is a measure of the average kinetic energy of the particles in a gas
2 gases at the same temperature have the same average kinetic energy

5. Explaining the behavior of gases
Compression and expansion:
A gas will expand to fill its container
Random motion of gas particles fill the empty spaces and it expands until the container stops it.
Large amounts of empty space between gas particles allow it to be compressed (squeezed into a smaller space)

6. Explaining the behavior of gases
Diffusion refers to the movement of one material through another
Gas particles flow past each other easily because there are no significant forces of attraction between them.
Particles diffuse from areas of high concentration to areas of low concentration

7. Explaining the behavior of gases
Effusion – a gas escaping through a tiny opening
Gases with a higher mass effuse slower than gases with less mass
Example: A tire deflating from a puncture

8. Gas pressure 1 atm = 101.3 kPa = 760 mm Hg = 760 Torr
Pressure is force per unit area.
When gas particles collide with the walls of their container, they exert pressure on the walls.
SI unit for pressure is the Pascal (Pa)
1 atm = kPa = 760 mm Hg = 760 Torr
Barometer = instrument that measures pressure of the atmosphere
Manometer = instrument that measures pressure of a gas in a closed container

9. Temperature Applies to solids, liquids, and gases
Increasing the temp causes an increase in the average kinetic energy of the particles
At a given temp, all particles of a substance have the same average kinetic energy
Kelvin (oC+273) = SI unit of temp
Absolute zero = lowest temp on Kelvin scale (0K = -273oC ~ -460oF)
Movement of all particles stops at this temp

10. Forces of Attraction
The attractive forces that hold particles together in ionic and covalent bonds are called intramolecular forces. (within the molecule)
Intermolecular forces hold particles of different molecules together. (between molecules)
There are three types of intermolecular forces: dispersion forces, dipole–dipole forces, and hydrogen bonds.

11. Liquids Liquids: Fixed volume, no fixed shape
Densities are much greater than that of gases
Particles are packed closer together
Is a fluid – has the ability to flow and change shape

12. Liquids Viscosity – measure of the resistance of a liquid to flow
Example: water vs. molasses
Viscosity is affected by the type of intermolecular forces and by the temperature
As temperature increases, viscosity decreases

13. Liquids
Surface Tension: The particles on the surface of a liquid are being pulled down by intermolecular forces (between two molecules)
The stronger the attraction between particles the stronger the surface tension

14. Liquids
Capillary action occurs when adhesive forces are greater than cohesive forces
Adhesion is the force of attraction between molecules that are different, such as water molecules and the molecules of silicon dioxide in glass.
Cohesion is the force of attraction between identical molecules, such as water molecules
Example: water in a graduated cylinder

15. Solids Solids: Particles in a solid are in constant motion (vibrating)
Definite shape and volume
Very strong attractive forces acting between molecules
More dense than most liquids
Most solids are in the shape of crystals (repeating geometric patterns)

16. Solids
The type of ions and the ratio of ions determine the structure and the shape of the crystal.

17. Solids
The particles in an amorphous solid are not arranged in a regular, repeating pattern and do not form crystals (they can take on different shapes).
Examples of amorphous solids include glass, rubber, and many plastics.