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Intermolecular Forces

Forces that exist between molecules, responsible for the physical properties of substances such as boiling points and melting points.

Intramolecular Forces

Forces that hold atoms together within a molecule, such as covalent or ionic bonds.

Van der Waals Forces

A category of intermolecular forces that includes dipole-dipole interactions, London dispersion forces, and hydrogen bonding.

Dipole-Dipole Forces

Attractive forces between polar molecules due to the positive end of one molecule being attracted to the negative end of another.

London Dispersion Forces

Weak forces that result from temporary shifts in electron density, causing temporary dipoles in neighboring molecules.

Hydrogen Bonding

A strong form of dipole-dipole interaction that occurs when hydrogen is bonded to highly electronegative atoms like nitrogen, oxygen, or fluorine.

Cohesive Forces

Intermolecular forces that bind like molecules to one another (e.g. hydrogen bonding).

Adhesive Forces

Intermolecular forces that bind a substance to a surface.

Viscosity

The resistance of a liquid to flow; depends on the strength of intermolecular forces.

Boiling Point

The temperature at which the vapor pressure of a liquid equals the external pressure surrounding the liquid.

Freezing Point

The temperature at which a pure substance changes from a liquid to a solid.

Melting Point

The temperature at which a solid becomes a liquid.

Phase Change

The transition of a substance from one state of matter to another (solid, liquid, gas).

Critical Temperature

The temperature above which it is impossible for a substance to exist as a liquid, no matter the pressure.

Vapor Pressure

The pressure exerted by the vapor in thermodynamic equilibrium with its condensed phases at a given temperature.

Surface Tension

The energy required to increase the surface area of a liquid due to cohesive forces among molecules at the surface.

Capillary Action

The ability of a liquid to flow in narrow spaces without the assistance of external forces, due to adhesion and cohesion.

Ionic Solid

A solid consisting of a lattice of ions held together by electrostatic forces.

Molecular Solid

A solid formed from molecules held together by intermolecular forces.

Covalent Network Solid

A solid consisting of a network of covalently bonded atoms.

Metallic Solid

A solid composed of metal atoms bonded by metallic bonds, characterized by delocalized electrons.

Phase Diagram

A graphical representation of the physical states of a substance under different conditions of temperature and pressure.