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Refers to species that have only six electrons in the highest energy level of the central element (many Lewis acids).

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Heat of Crystallization

The amount of heat that must be removed from one gram of a liquid at its freezing point to freeze it with no change in temperature.

Rate-law Expression

Equation relating the rate of a reaction to the concentrations of the reactants and the specific rate of the constant.

Reaction Quotient

The mass action expression under any set of conditions (not necessarily equlibrium), its magnitude relative to K determines the direction in which the reaction must occur to establish equilibrium.

D -Transition elements (metals)

B Group elements except IIB in the periodic table, sometimes called simply transition elements EX. Fe, Ni, Cu, Ti .
For further information see Metals.

Primary Standard

A substance of a known high degree of purity that undergoes one invariable reaction with the other reactant of interest.


The reaction of an acid with a base to form a salt and water. Usually, the reaction of hydrogen ions with hydrogen ions to form water molecules.

DP number

The degree of polymerization, the average number of monomer units per polymer unit.

Dry Cells

Ordinary batteries (voltaic cells) for flashlights. radios, and so on, many are Leclanche cells.

Chemical Bonds

The attractive forces that hold atoms together in elements or compounds.

Lewis Acid

Any species that can accept a share in an electron pair.