valence

valence
va·lence 'vā-lən(t)s n
1 a) the degree of combining power of an element or radical as shown by the number of atomic weights of a monovalent element (as hydrogen) with which the atomic weight of the element or the partial molecular weight of the radical will combine or for which it can be substituted or with which it can be compared
b) a unit of valence <the four \valences of carbon>
2 a) relative capacity to unite, react, or interact (as with antigens or a biological substrate)
b) the degree of attractiveness an individual, activity, or object possesses as a behavioral goal <the relative potency of the \valences of success and failure (Leon Festinger)>

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va·lence (vaґlens) [L. valēre to be strong] 1. a positive number that represents the combining power of an element in a chemical compound, i.e., the number of bonds each atom of that element makes with other atoms. In this most general sense “valence” has been superseded by the concept “oxidation number.” However, “valence” is still used to indicate (a) the number of covalent bonds formed by an atom in a covalent compound or (b) the charge on a monatomic or polyatomic molecule. 2. in immunology, (a) the number of antigen-binding sites possessed by an antibody molecule, two per immunoglobulin monomer, or (b) the number of antigenic determinants possessed by an antigen, usually a large number.

Medical dictionary. 2011.

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