Valence

noun
1.
Chemistry.

the quality that determines the number of atoms or groups with which any single atom or group will unite chemically.
the relative combining capacity of an atom or group compared with that of the standard hydrogen atom. The chloride ion, Cl–, with a valence of one, has the capacity to unite with one atom of hydrogen or its equivalent, as in HCl or NaCl.

2.
Immunology. the number of determinants per molecule of antigen.
3.
the capacity of one person or thing to react with or affect another in some special way, as by attraction or the facilitation of a function or activity.
noun
1.
a city in and the capital of Drôme, in SE France.
noun
1.
a department in SE France. 2533 sq. mi. (6560 sq. km).
Capital: Valence.
noun (chem)
1.
another name (esp US and Canadian) for valency
2.
the phenomenon of forming chemical bonds
noun
1.
a town in SE France, on the River Rhône. Pop: 64 260 (1999)
noun
1.
a department of SE France, in Rhône-Alpes region. Capital: Valence. Pop: 452 652 (2003 est. Area: 6561 sq km (2559 sq miles)

valence va·lence (vā’ləns) or va·len·cy (-lən-sē)
n.

The combining capacity of an atom or a radical determined by the number of electrons that it will lose, add, or share when it reacts with other atoms.

A positive or negative integer used to represent this capacity.

The number of components of an antigen molecule to which an antibody molecule can bind.

The attraction or aversion that an individual feels toward a specific object or event.

valence
(vā’ləns)
A whole number that represents the ability of an atom or a group of atoms to combine with other atoms or groups of atoms. The valence is determined by the number of electrons that an atom can lose, add, or share. An atom’s valence is positive if its own electrons are used in forming the bond, or negative if another atom’s electrons are used. For example, a carbon atom can share four of its electrons with other atoms and therefore has a valence of +4. A sodium atom can receive an electron from another atom and therefore has a valence of -1. (In this book the distinction between positive and negative valences is ignored unless it is relevant.) The valence of an atom generally indicates how many chemical bonds it is capable of forming with other atoms. Also called valence number, oxidation state.
valence [(vay-luhns)]

A number characterizing an atom, equal to the number of valence electrons.