universal gas law constant (R) constant equal to PV nT , where the pressure, volume, moles, and temperature of the gas are represented by P, V, n, and T , respectively; the value and units of R depend on the units of P and V, and two commonly used values of R are 0.08206 L atm K−1 mol−1 and 8.314 J K−1 mol−1 unsaturated compound an organic molecule containing double or triple bonds unsaturated solution a solution in which a given amount of solvent has dissolved less than the absolute maximum amount solute at that temperature unshared electron pair an unshared electron pair, also known as a non-bonding pair of electrons or as a lone pair of electrons, is found in a filled valence orbital that is not used in the formation of a covalent bond
V valence electrons the electrons in the outermost principal quantum level of an atom valence shell the outermost energy level of an atom van’t Hoff factor the number of particles that the solute will dissociate into upon mixing with the solvent vapor the gaseous phase of a substance that exists even though the temperature is below the boiling point of the substance vapor pressure pressure of the vapor in the space above the liquid velocity distance traveled in one second. voltage the potential difference between two points in an electric circuit volume the amount of space an object occupies VSEPR (valence shell electron pair repulsion) theory a theory whose main postulate is that the structure around a given atom in a molecule is determined by minimizing electron-pair repulsion
W wavelength (λ) the length of a single wave from peak to peak (crest to crest or trough to trough) wave-particle duality the concept that all matter and energy exhibit both wave-like and particle-like properties weak acid acid that does not completely dissociate in water weak base base that does not completely dissociate in water weight the force of attraction between the object and the earth (or whatever large, gravity-producing body the object is located on) work force (any push or pull) applied over a distance
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