Chemistry Reference
In-Depth Information
total bond order
(20.3) The number of electron pairs shared
by an atom in a molecule or ion.
total equation
(9.2) The equation representing the complete
compounds undergoing reaction, as opposed to an ionic
or a net ionic equation.
tracer
(21.1) A radioactive isotope of an element used to de-
termine what happens to the element, often in some bio-
chemical system.
transition element
(1.5) Any element in the groups that start
in the fourth period of the periodic table, having atomic
numbers 21-30, 39-48, 57, 72-80, or 104-112.
transmutation
(21.3) The conversion of one element into
another by a nuclear reaction.
trigonal planar molecule
(13.4) A molecule with atoms ori-
ented toward the corners of an equilateral triangle, with
the central atom in the same plane.
trigonal pyramidal molecule
(13.4) A molecule with atoms
oriented toward the corners of an equilateral triangle,
with the central atom out of that plane.
triple bond
(5.5) A covalent bond consisting of three pairs
of electrons shared between two atoms.
tritium
(21.4) The isotope
valence electron
(5.2) An electron in or from the outermost
electron-containing shell of an uncombined atom.
valence shell
(5.2) The outermost shell containing electrons
in an uncombined atom, or that same shell even when
the atom is combined in a compound.
van der Waals force
(13.6) An intermolecular force result-
ing from instantaneous dissymmetry of charge in other-
wise nonpolar molecules.
vapor
(14.2) A gas in contact with its liquid (or solid) phase.
vapor pressure
(12.6, 14.2) The pressure of the vapor in
equilibrium with its liquid (or solid).
vapor-pressure lowering
(15.6) A decrease in the vapor
pressure of a solvent due to the presence of a solute.
vaporization
(14.2) A phase change from liquid to gas
(vapor).
volatile
(15.6) Easily vaporized.
voltage
(17.2) Electric potential.
voltaic cell
(17.1) An apparatus that provides a combination
of half reactions that can produce an electric current.
volume
(2.3) The extent of space occupied by a sample of
matter.
volume ratio
(12.9) The ratio of volumes of gases involved
in a chemical reaction.
3
H.
uncertainty principle
See
Heisenberg uncertainty principle
.
unit
(2.1) A standard division of measure having a certain
value; for example, the meter is the primary metric unit
of length.
unsaturated fat
(20.5) A fat that contains one or more
carbon-carbon multiple bonds per molecule.
unsaturated hydrocarbon
(20.1) A compound containing
only carbon and hydrogen and having one or more mul-
tiple bonds per molecule.
unsaturated solution
(15.2) A solution that contains less
solute than it could hold stably at a given temperature.
unshared pair
(5.5) A pair of electrons in a molecule or ion
that is not shared between atoms.
urea
(Chapter 20, Introduction) (an organic
compound despite its lack of carbon-carbon or carbon-
hydrogen bonds).
water ionization constant
(19.3) The equilibrium constant
for the autoionization of water; symbolized
K
w
;
at
[H
3
O
][OH
]
10
14
.
25°C,
K
w
1.0
wavelength
(4.1) The length of a single wave.
weak acid
(8.4) An acid that reacts only partially with water
to form ions.
weak base
(8.4) A base that reacts only partially with water
to form ions.
weak electrolyte
(9.1) A compound that is only slightly ion-
ized in aqueous solution.
weighted average
(3.4) The average value of several types
of items, taking into account the number of individual
items of each type.
work
(14.4) All forms of energy except heat.
NH
2
CONH
2
