Page 327 - Theory and Problems of BEGINNING CHEMISTRY

316 GLOSSARY

dimensional analysis factor-label method.

direct proportion as the value of one variable rises, the value of the other rises by the same factor. Directly
proportional variables have a constant quotient, for example, V/T = k for a given sample of a gas at constant
pressure.

disintegration spontaneous emission from a radioactive nucleus of an alpha, a beta, or a gamma particle.
disproportionation reaction of a reactant with itself to produce a product with a lower oxidation number and
another with a higher oxidation number.

double bond a covalent bond with two shared pairs of electrons.
double decomposition double substitution.
double replacement double substitution.
double-substitution reaction a reaction of (ionic) compounds in which the reactant cations swap anions. Also
called double replacement, double decomposition, or metathesis.

EE key the key on a calculator meaning “times 10 to the power,” used to enter exponential numbers.
effusion the escape of gas molecules through tiny openings in the container holding the gas.
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Einstein’s equation E = mc .
elastic collision a collision in which the total kinetic energy of the colliding particles does not change.
electric current the concerted (nonrandom) movement of charged particles such as electrons in a wire or ions
in a solution.

electrode a solid conductor of electricity used to connect a current-carrying wire to a solution in an electrolysis
cell or a galvanic cell.
electrolysis a process in which an electric current produces a chemical reaction.
electron a negatively charged particle that occurs outside the nucleus of the atom and is chiefly responsible for
the bonding between atoms.
electron dot diagram a scheme for representing valence electrons in an atom with dots.
electronegativity the relative attraction for electrons of atoms involved in covalent bonding. The higher the
attraction, the higher the electronegativity.
electronic charge the magnitude of the charge on an electron; 1.60 × 10 −19 C.
electroplating depositing a thin layer of a metal on the surface of another metal by means of an electrolysis
reaction.
element a substance that cannot be broken down into simpler substances by ordinary chemical means.
empirical formula formula for a compound that contains the simplest whole number ratio of atoms of the
elements.
endpoint the point in a titration at which the indicator changes color permanently and the titration is stopped.
-ene name ending for the alkene series of hydrocarbons.

energy the capacity to produce change or the ability to do work.
equation notation for a chemical reaction containing formulas of each reactant and product, with coefficients
to make the numbers of atoms of each element equal on both sides.

equilibrium state in which two opposing processes occur at equal rates, causing no apparent change.