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.
Immunology. the number of determinants per molecule of antigen.
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.
early 15c., "extract, preparation," from Latin valentia "strength, capacity," from valentem (nominative valens), present participle of valere "be strong" (see valiant). Meaning "combining power of an element" is recorded from 1884, from German Valenz (1868), from the Latin word.
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 numberoxidation state