Ch 11 Liquids and Intermolecular forces

Intermolecular Forces

Forces that exist between molecules, generally much weaker than intramolecular forces.

Intramolecular Forces

Forces that exist within a molecule, such as ionic, metallic, or covalent bonds.

Dispersion Forces

Weak intermolecular attractions that arise due to instantaneous dipoles in neutral molecules.

Polarizability

The measure of how easily a molecule's electron cloud can be distorted to form an instantaneous dipole.

Dipole-Dipole Interactions

Electrostatic attractions between the partially positive end of one polar molecule and the partially negative end of another.

Hydrogen Bonding

An attraction between a hydrogen atom bonded to a very electronegative atom and another electronegative atom.

Ion-Dipole Forces

Attractive forces between an ion and a polar molecule, essential for ionic compounds in polar solvents.

Viscosity

The resistance of a liquid to flow; higher viscosity means slower flow.

Surface Tension

The energy required to increase the surface area of a liquid by a unit amount.

Cohesive Forces

Intermolecular forces that bind similar molecules to one another.

Adhesive Forces

Intermolecular forces that bind a substance to a surface.

Capillary Action

The rise of liquids up very narrow tubes due to adhesive and cohesive forces.

Melting (Fusion)

The process where solid particles gain enough energy to enter the liquid state.

Vapor Pressure

The pressure exerted by a vapor in equilibrium with its liquid at a given temperature.

Dynamic Equilibrium

A condition where two opposing processes occur simultaneously at equal rates.

Triple Point

The point where all three phases of a substance are in equilibrium.

Liquid Crystals

Substances that exhibit a state between liquid and solid, often used in displays.

Nematic Liquid Crystal

A type of liquid crystal with aligned long axes, but no specific end alignment.

Smectic Liquid Crystals

Liquid crystals that maintain long-axis alignment and pack into layers.

Cholesteric Liquid Crystals

Liquid crystals arranged in layers with a spiral pattern due to fixed angle rotations in layers.

What are the covalent network solids?

The basic idea is that to make a network of covalent bonds, each atom (or many of the atoms) have to make 3 or 4 bonds to other atoms. This means that covalent-network solids usually include carbon, silicon, and their neighbors in the periodic table.