Intermolecular Forces


A homogeneous part of the system in contact with other parts of the system but seperated from them by a well defined boundary.

Ex: A glass with both water and ice

(solid and liquid phase)

Intermolecular Forces
The attractive forces between the molecules
Intramolecular forces
Holds atom together in a molecule
Dipole-Dipole Forces
Attractive Forces between polar molecules
Ion-Dipole Forces
Attractive Forces between an ion and a polar molecule
Dispersion Forces
Attractive forces that arise as a result of temporary dipoles induced in atoms or molecules

The ease with which the electron distribution in the atom or molecule can be distorted


Increases with greater # of electrons and more diffuse in the electron cloud


Hydrogen Bond
A special dipole-dipole interaction between the hydrogen atom in a polar N-H, O-H, or F-H bond and an electronegative O, N, or F atom
Surface tension
The amount of energy required to stretch or increase the surface of a liquid by a unit area
Intermolecular attraction between like molecules
Attraction between unlike molecules
The measure of a fluid’s resistance to flow
Crystalline Solid

Possesses rigid and long-range order


Occupy specific (predictable) positions

Amorphous Solids
do not;possess a well-defined arrangement or a long-range molecular order
unit cell
Basic, repeating stuctural unit of a crystalline solid
Three types of Cubic Cells

Simple Cubic

Body-Centered Cubic

Face-Centered Cubic

An optically transparent fusion product of inorganic materials that has cooled to a rigid state without crystallizing
Equilibrium Vapor Pressure
The vapor pressure measured when a dynamic equilibrium exists between condensation and evaporation
Molar Heat of Vaporization
The energy required to vaporize 1 mole of a liquid at its boiling point
boiling point
The temperature at which the (equilibrium) vapor pressure of a liquid is equal to the external pressure
Normal boiling point
The temperature at which a liquid boils when the external pressure is 1 atmosphere (atm)
Critical Temperature
The temperature above which the gas cannot be made to liquefy, no matter how great the applied pressure
Critical Pressure
The minimum pressure that must be applied to bring about liquefaction at a critical temperature
Melting Point or Freezing Point of a Liquid
The temperature at which the solid and the liquid phaes coexist in equilibrium
Molar Heat of Fusion
The energy required to melt 1 mole of a solid substance at its freezing point
Molar Heat of Sublimation
The energy required to sublime 1 mole of a solid
phase diagram
summarizes the conditions at which a substance exists as a solid, liquid or gas