Chemistry - Ch 12 Vocab

Kinetic-molecular Theory

Describes the behavior of matter in terms of particles in motion

Elastic Collision

A collision in which no kinetic energy is lost

Temperature

A measure of the average kinetic energy of the particles in a sample of matter

Diffusion

The term used to describe the movement of one material through another

Graham’s Law of Effusion

States that the rate of effusion for a gas is inversely proportional to the square root of its molar mass

Pressure

Force per unit area

Barometer

An instrument used to measure atmospheric pressure

Pascal

Equal to a force of one newton per square meter

Atmosphere

Equal to 760 mmHg or 760 torr or 101.3 kilopascals (kPa)

Dalton’s Law of Partial Pressures

States that the total pressure of a mixture of gases is equal to the sum of the pressures of all the gases in the mixture

Dispersion Force

A weak force that results from temporary shifts in the density of electrons in electron clouds

Dipole-dipole Forces

Attractions between oppositely charged regions of polar molecules

Hydrogen Bond

A dipole-dipole attraction that occurs between molecules containing a hydrogen atom bonded to a small, highly electronegative atom with at least one lone electron pair

Viscosity

A measure of the resistance of a liquid to flow

Surface Tension

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

Surfactant

Compounds that lower the surface tension of water

Crystalline Solid

A solid whose atoms, ions, or molecules are arranged in an orderly, geometric structure

Unit Cell

The smallest arrangement of atoms in a crystal lattice that has the same symmetry as the whole crystal

Allotrope

An element that exists in different forms at the same state

Amorphous Solid

A solid in which the particles are not arranged in a regular, repeating pattern

Melting Point

The temperature at which the forces holding its crystal lattice together are broken and it becomes a liquid

Vaporization

The process by which a liquid changes to a gas or vapor

Evaporation

When vaporization occurs only at the surface of a liquid

Vapor Pressure

The pressure exerted by a vapor over a liquid

Boiling Point

The temperature at which the vapor pressure of a liquid equals the external or atmospheric pressure

Freezing Point

The temperature at which a liquid is converted into a crystalline solid

Condensation

The process by which a gas or vapor becomes a liquid

Deposition

The process by which a substance changes from a gas or vapor to a solid without first becoming a liquid

Phase Diagram

A graph of pressure versus temperature that shows in which phase a substance exists under different conditions of temperature and pressure

Triple Point

The point on a phase diagram that represents the temperature and pressure at which three phases of a substance can coexist