Solids

1. Solids Solid- has a definite volume and a definite shape. Motion of particles are restricted in solids because of the stronger intermolecular forces. Defn. Crystalline Solid: consists of crystals which the particles are arranged in an orderly geometric repeating pattern. Defn. Amorphous Solid: A non-crystalline solid in which the particles are arranged randomly. Characteristics of Solids 1. Definite Melting Point: temperature in which a solid becomes a liquid. 2. High Density and Incompressibility: 3. Low Rate of Diffusion Defn: Crystalline Structure: total three dimensional arrangement of particles of a crystal. Defn: Unit Cell: The smallest portion of a crystal lattice that shows the three dimensional pattern of the entire lattice.

2. Changes of State Defn: Phase: any part of a system that has uniform composition. Defn: Equilibrium: A dynamic condition in which two opposing changes occur at equal rates in a closed system. Defn: Equilibrium vapor pressure: Pressure exerted by a vapor in an equilibrium with its corresponding liquid at a given temperature. Defn: Volatile liquid: Liquids that evaporate readily. Defn: Molar enthalpy of vaporization:∆HvAmount of energy needed to vaporize one mole of liquid at the liquids boiling point. Temperature at the boiling point remains constant despite the amount of energy added. Defn: Molar enthalpy of fusion ∆Hf Amount of energy needed to melt one mole of a solid.

3. Defn: Phase Diagram: A graph of pressure versus temperature that shows the condition under which the phases of a substance exists.

4. Defn: Critical Temperature: the temperature above which the substance cannot exist in the liquid state. Defn: Triple point: Indicates the temperature and pressure conditions at which the solid, liquid and vapor of the substance can co-exist at equilibrium.