Chemistry Reference
In-Depth Information
definite proportions
See
law of definite proportions
.
degenerate
(4.4) Having the same energy.
density
(2.5) The mass per unit volume of a sample of
matter.
deuterium
(21.4) The isotope of hydrogen with mass num-
ber 2: symbolized or D.
deuteron
(21.4) A deuterium nucleus; symbolized d.
diatomic molecule
(5.1) A molecule containing two atoms.
dimensional analysis
See
factor label method
.
dipole
(13.5) See
dipole moment
.
dipole moment
(13.5) An unequal distribution of charge in
a molecule resulting from unsymmetrical orientation of
polar bonds; also referred to as a dipole.
direct proportionality
(12.3) The relationship in which one
variable changes by the same factor as another.
disaccharide
(20.5) A sugar containing two simple sugar
molecules.
discrete energy levels
(4.2) Atomic energy levels that have
specific energies.
disintegration
(21.1) A reaction of an unstable nucleus.
disproportionation
(16.4) The reaction of a species with it-
self to produce products having higher and lower oxida-
tion numbers; also called autooxidation-reduction.
dissociation
(Chapter 9, Introduction, 19.2) Separation of
ions from their close proximity in a solid lattice to a dis-
tance when dissolved in a solvent.
dissolve
(1.2) To go into solution, making a homogeneous
mixture.
distillation
(14.2) The conversion of a liquid to a gas and
then back to a liquid to separate it from impurities.
double bond
(5.5) The sharing of two pairs of electrons be-
tween two atoms.
double displacement reaction
(8.3) The reaction of two
compounds in which two other compounds are pro-
duced, as a result of a trade of the anions by the cations.
double substitution reaction
(8.3) A double displacement
reaction.
ductile
(1.5) Capable of being drawn into a wire.
duet
(5.2) A pair of electrons associated with a hydrogen,
helium, lithium, or beryllium atom, resulting in the sta-
ble configuration of a noble gas (helium).
dynamic state
(18.2) A state in which two opposite
processes occur at equal rates.
electrolysis cell
(17.4) An apparatus in which electric en-
ergy can be used to produce chemical reactions.
electromagnetic radiation
(21.1) Any form of light energy:
visible light, ultraviolet light, X-rays, gamma rays, in-
frared radiation, or microwaves.
electromagnetic spectrum
(4.1) The complete collection of
electromagnetic waves, including visible light, infrared,
ultraviolet, X-rays, gamma rays, and microwaves.
electron
(3.3) A negatively charged subatomic particle; a
fundamental particle of nature.
electron affinity
(13.2) The energy liberated when a gaseous
atom acquires an electron to form a gaseous anion.
electron group
(13.4) A single electron pair, the 4 or 6 elec-
trons in a double or triple bond, or rarely, a single elec-
tron, which are attached to a central atom of a molecule
or polyatomic ion.
electron sharing
(5.5) The sharing of electrons between
atoms to form covalent bonds.
electronegative
(5.1) A large tendency of an atom to attract
electrons in the formation of a compound.
electronegativity
(5.1, 13.3) A semiquantitative measure of
the tendency of an atom to attract electrons in the for-
mation of a compound.
electronic charge
(3.3) The charge on one electron,
2
H
(
2
H)
1.60
10
19
coulomb.
electronic configuration
(4.5) The arrangement of the elec-
trons in an atom, ion, or molecule.
electronic structure
See
electronic configuration
.
electropositive
(5.1) Having only a small tendency to attract
electrons.
element
(1.1) A substance that cannot be broken down into
simpler substances by chemical means; one of the basic
building blocks of which all matter is composed.
elemental
(5.1) Existing as an element; not combined into
any compound.
empirical formula
(7.4) The simplest formula for a com-
pound that shows the atomic ratio of elements in the
compound.
end point
(11.3) The point in a titration when the indicator
signals that the reaction is complete.
endothermic process
(14.3) A process in which energy is
absorbed from outside the system.
energy
(1.3) The capacity to do work.
energy level diagram
(4.7) A graph in which horizontal
lines represent the orbitals of an atom, those with higher
energies toward the top, and in which arrows may be
used to represent electrons.
enthalpy change
(14.4) The heat (under certain familiar
conditions) involved in a process; symbolized
enthalpy of formation
(14.4) The enthalpy change in the
formation of a substance from its elements in their stan-
dard states; symbolized
enthalpy of fusion
See
heat of fusion
.
enthalpy of vaporization
See
heat of vaporization
.
enzyme
(18.1) A biochemical catalyst.
E
mc
2
,
Einstein's equation
(21.3) The equation which
relates the energy produced to the mass of matter con-
verted to energy in a nuclear reaction.
electrochemistry
(Chapter 17, Introduction) The branch of
chemistry dealing with the interaction of chemical reac-
tions and electricity.
electrode
(5.2) The solid portion of an electrochemical reac-
tion apparatus at which a change from electron conduc-
tion to ion conduction, or vice versa, takes place.
electrolysis
(17.4) Production of a chemical reaction by
means of an electric current.
¢
H
.
¢
H
f
.
