amorphous solid
(p. 403) A solid in which particles are not arranged in a regular, repeating pattern that often is formed when molten material cools too quickly to form crystals.
atmosphere
(p. 390) The unit that is often used to report air pressure
barometer
(p. 389) An instrument that is used to measure atmospheric pressure.
boiling point
(p. 406) The temperature at which a liquid's vapor pressure is equal to the external or atmospheric pressure.
condensation
(p. 407) The energy-releasing process by which a
gas or vapor becomes. a liquid.
crystalline solid
(p. 400) A solid whose atoms, ions, or molecules are arranged in an orderly, geometric, three-dimensional struc- ture; can be classified by shape and by composition.
Dalton's law of partial pressures
(p. 391) 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.
deposition
(p. 408) The energy-releasing process by which a substance changes from a gas or vapor to a solid without first becoming a liquid.
diffusion
(p. 387) The movement of one material through another from an area of higher concentration to an area of lower concentration.
dipole-dipole forces
(p. 394) The attractions between oppositely charged regions of polar molecules.
dispersion forces
(p. 393) The weak forces resulting from temporary shifts in the density of electrons in electron clouds.
elastic collision
(p. 386) Describes a collision in which kinetic energy may be transferred between the colliding particles but the total kinetic energy of the two particles remains the same.
evaporation
(p. 405) The process in which vaporization occurs only at the surface of a liquid.
freezing point
(p. 408) The temperature at which a liquid is converted into a crystalline solid.
Graham's law of effusion
(p. 387) States that the rate of effusion for a gas is inversely proportional to the square root of its molar mass.
hydrogen bond
(p. 395) A strong dipole-dipole attraction between molecules that contain a hydrogen atom bonded to a small, highly electronegative atom with at least one lone electron pair.
kinetic-molecular theory
(p. 385) Explains the properties of gases in terms of the energy, size, and motion of their particles.
melting point
(p. 405) For a crystalline solid, the temperature at which the forces holding a crystal lattice together are broken and it becomes a liquid.
pascal
(p. 390) The SI unit of pressure; one pascal (Pa) is equal to a force of one newton per square meter.
phase diagram
(p. 408) A graph of pressure versus temperature that shows which phase a substance exists in under different conditions of temperature and pressure.
pressure
(p. 388) Force applied per unit area.
sublimation
(p. 407) The energy-requiring process by which a solid changes directly to a gas without first becoming a liquid.
surface tension
(p. 398) The energy required to increase the surface area of a liquid by a given amount; results from an uneven distribution of attractive forces.
surfacrant
(p. 398) A compound, such as soap, that lowers the surface tension of water by disrupting hydrogen bonds between water molecules; also called a surface active agent.
temperature
(p. 386) A measure of the average kinetic energy of the particles in a sample of matter.
triple point
(p. 409) The point on a phase diagram representing the temperature and pressure at which the three phases of a substance (solid, liquid, and gas) can coexist.
unit cell
(p. 400) The smallest arrangement of connected points that can be repeated in three directions to form a crystal lattice.
vaporization
(p. 405) The energy-requiring process by which a liquid changes to a gas or vapor.
vapor pressure
(p. 406) The pressure exerted by a vapor over a liqui
viscosity
(p. 397) A measure of the resistance of a liquid to flow, which is affected by the size and shape of particles, and generally increases as the temperature decreases and as intermolecular forces increase.