IMF & Properties of Solutions

Intermolecular Forces

Attractive forces between molecules. These determine many bulk properties of substances such as boiling pt, melting pt., etc.

Intramolecular Forces

Attractive forces within molecules. These are the forces that lead to bonding.

Ion-Dipole Forces

A strong electrostatic attractive force between an ion and a polar molecule

Dipole-Dipole Forces

a medium strength electrostatic attractive force between two

polar molecules

Dipole-Induced Dipole Forces

The (+) partially charged poles of a polar molecule attract the electrons in a non-polar molecule, causing the e’ distribution to be asymmetrical. This creats or “induces” a dipole in a non-polar molecules.

Dispersion Forces

weak attractive forces that arises as a result of temporary dipoles induced in atoms of molecules.

Hydrogen Bonding

An especially strong type of dipole-dipole force between a hydrogen atom in a really polar bond (such as N-H, O-H, F-H) and the O, N, or F of another molecule.

Evaporation/Vaporization

Conversion of a liquid to a gas

Vapor Pressure

How fast it takes to convert from liquid to gas (depends on IMFs)

Critical Temperature

Temperature above which the vapor cannot be liquefied no matter how much pressure is applied. Beyond this temperature, a “fluid” that has properties somewhere between a liquid and a gas (high density, but it’s a gas) is formed.

Critical Pressure

The pressure required to produce liquefaction at the critical temperature. Remember, once you go past the (Tc), you will never achieve liquefaction.

Surface Tension

due to the increase in the attractive forces between molecules at the surface of the liquid compared to the forces between molecules in the center, or bulk, of the liquid.

Capillary Action

because of high intermolecular forces (surface tension), a liquid can spontaneously rise in a capillary tube (very small diameter glass tube

Cohesion

the intermolecular attraction between LIKE molecules (water & water).

Adhesion

the intermolecular attraction between UNLIKE molecules (water & glass).

Viscosity

A measure of a fluids resistance to flow. Viscosity is used with motor oils.

Ionic Crystals

Crystals of ionic compounds

• Hard, brittle, HIGH melting point, poor conductivity of heat and electricity.

Covalent Crystals

Crystals of a network of 100% covalently bonded atoms

• Hard, HIGH melting point, usually poor conductor of heat and electricity

Molecular Crystals

Crystals of molecular compounds

• Soft, LOW melting points (< 100°C), poor conductors of heat and electricity.

Metallic Crystals

Crystals of metals atoms

• Soft to hard, low to high melting points, good conductors of heat and electricity