1. Chapter 10: States of Matter
Chemistry by Addison/Wesley

2. 10.1 The Nature of Gases Kinetic Theory A gas is composed of particles
Particles are small, hard spheres
Particles in a gas move in a constant random motion
Travel in straight paths and move independently of each other
All collisions are perfectly elastic
Kinetic energy is transferred without loss; total kinetic energy remains constant

3. Gas Pressure
Gas pressure is the force exerted by a gas per unit surface area
No particles = no pressure
This empty space is called a vacuum
Atmospheric pressure results from the collisions of air molecules with objects
Barometers are devices used to measure atmospheric pressure
Pascal (Pa) - SI unit of pressure

4. Pressure
Atmospheric pressure at sea level is about kilopascals (kPa)
At sea level, the atmospheric pressure is strong enough to support a mercury column 760mm high
One standard atmosphere is required to support 760 mm of mercury
101.3 kPa = 1 atm = 760 mm Hg

5. Energy and Temperature
Objects tend to have a wide range of kinetic energy
Most particles fall into an average range of kinetic energy
Increase in average kinetic energy causes an increase in temperature
Kelvin temperature is a relationship between the increase in temperature and average kinetic energy

6. 10.2 The Nature of Liquids
Unlike gases, the molecules of a liquid have attractive forces
The molecules can move over one another which gives them the ability to flow
Molecules vibrate and spin
Adds to the molecules kinetic energy
Still not enough kinetic energy to over come the attractive forces

7. Evaporation
Vaporization is the conversion of a liquid to a gas or vapor
When this occurs at the surface of a liquid that is not boiling, it is known as evaporation
Those molecules with higher average kinetic energy are the ones that escape into a gas

8. Evaporation
Evaporation of a liquid in a closed container causes an increase in vapor pressure
Eventually, the number of particles condensing will equal the number of particles evaporating
Increase in temperature will result in an increase in kinetic energy

9. Boiling Point
The boiling point of a liquid is the point at which the vapor pressure equals the external pressure
Boiling, like evaporation, is a cooling process
The temperature never rises above the boiling point until all particles have been converted into a gas

10. 10.3 Nature of Solids
Molecules of a solid tend to vibrate around a fixed point
Solids tend to dense an incompressible
Melting point is the point at which the solid becomes a liquid
Melting point is the same as the freezing point
At this temperature, the solid and liquid substance are at equilibrium

11. Crystal Structure
In a crystal, the atoms of the solid are arranged in a repeating pattern called a crystal lattice
The shape of the crystal reflects the arrangement of the particles
The type of bonding determines the melting point of the solid
Crystals are arranged into seven crystal systems

12. Crystals
The smallest unit of a crystal that retains the geometric shape is a unit cell
Some solids can exist in more than one form
Carbon is an example
Diamond, graphite, and buckminsterfullerene
These are known as allotropes

13. Amorphous Solids Amorphous solids lack internal order
Glass is an example of an amorphous solid
Glass is also called a super cooled liquid

14. 10.4 Changes of State
Phase Diagram is a representation of how temperature and pressure affect the state of matter
In a phase diagram, the melting points and boiling points are plot on a graph as the temperature and pressure change
The triple point is the point at which the two plot lines come together

15. Sublimation Sublimation is the conversion of a solid directly to a gas
Freeze drying process uses sublimation
Solid air fresheners and dry ice are also examples of materials the sublimate