Medical Definition of valence
1a: 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 comparedb: a unit of valence <the four valences of carbon>
2a: 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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