Page 328 - Theory and Problems of BEGINNING CHEMISTRY

GLOSSARY 317

equilibrium constant a constant equal to the ratio of concentrations of products to reactants, each raised to a
suitable power, which is dependent for a given reaction on temperature only.
equivalent the quantity of a substance, (1) in a redox reaction, that reacts with or produces 1 mol of electrons;
−
(2) in an acid-base reaction, that reacts with or produces 1 mol of H or OH ions.
+
equivalent mass the number of grams per equivalent of a substance.
ester an organic compound of the general type RCO 2 R .

ether an organic compound of the general type ROR .
CH 2 .
ethylene ethene; CH 2
event the reaction of one nucleus (plus a projectile, if any) in a nuclear reaction.
excess quantity more than sufficient of one reagent to ensure that another reagent reacts completely.
excited state the state of an atom with the electron(s) in higher energy levels than the lowest possible.
EXP key the key on a calculator meaning “times ten to the power,” used to enter exponential numbers.

exponent a superscript telling how many times the coefficient is multiplied by the base. For example, the
3
3
exponent in 2.0 × 10 is 3; the 2.0 is multiplied by 10 three times: 2.0 × 10 = 2.0 × 10 × 10 × 10.
3
exponential number a number expressed with a coefficient times a power of 10, for example, 1.0 × 10 .
extrapolation reading a graph beyond the experimental points.

factor-label method a method of problem solving that uses the units to indicate which algebraic operation to
do for quantities that are directly proportional; dimensional analysis.
feeble acid or base an acid or base that has practically no tendency to react with water.

fission the process in which a nucleus is split into two more or less equal parts by bombardment with a projectile
particle such as a neutron or a proton.
fluid a gas or liquid.

formula a combination of symbols with proper subscripts that identifies a compound or molecule.
formula mass the sum of the atomic masses of all the atoms in a formula.
formula unit the material represented (1) by the simplest formula of an ionic compound, (2) by a molecule, or
(3) by an uncombined atom.
functional group the reactive part of an organic molecule.
fusion (1) melting. (2) combining two nuclei in a nuclear reaction.

galvanic cell a cell in which a chemical reaction produces an electric potential.
gamma ray a stream of gamma particles, essentially photons of high-energy light with zero rest mass and zero
charge.
Graham’s law the rate of effusion or diffusion of a gas is inversely proportional to the square root of its
molecular mass.

gram the fundamental unit of mass in the metric system.
graphical formula a formula in which all atoms are shown with their bonding electron pairs represented by
lines; structural formula.

ground state the lowest energy state of an atom.