Definitions for valenceˈveɪ ləns
Random House Webster's College Dictionary
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 number of binding sites on a molecule, as an antibody or antigen.
Category: Genetics, Biochemistry
Origin of valence:
1865–70; < L valentia strength, worth =valent-, s. of valēns, prp. of valēre to be strong +-ia n. suffix; see -ence
a city in SE France. 70,307.
Category: Geography (places)
(biology) a relative capacity to unite or react or interact as with antigens or a biological substrate
(chemistry) a property of atoms or radicals; their combining power given in terms of the number of hydrogen atoms (or the equivalent)
the degree of combining power of an atom (or radical) as shown by the number of atoms of hydrogen (or of other monads, as chlorine, sodium, etc.) with which it will combine, or for which it can be substituted, or with which it can be compared; thus, an atom of hydrogen is a monad, and has a valence of one; the atoms of oxygen, nitrogen, and carbon are respectively dyads, triads, and tetrads, and have a valence respectively of two, three, and four
In chemistry, valence, also known as valency or valence number, is the number of valence bonds a given atom has formed, or can form, with one or more other atoms. For most elements the number of bonds can vary. The IUPAC definition limits valence to the maximum number of univalent atoms that may combine with the atom, that is the maximum number of valence bonds that is possible for the given element. The valence of an element depends on the number of valence electrons that may be involved in the forming of valence bonds. A univalent atom, ion or group has a valence of one and thus can form one covalent bond. A divalent molecular entity has a valence of two and can form two sigma bonds to two different atoms or one sigma bond plus one pi bond to a single atom. Alkyl groups and hydroxyl ions are univalent examples; oxo ligands are divalent. Over the last century, the concept of valence evolved into a range of approaches for describing the chemical bond, including Lewis structures, valence bond theory, molecular orbitals, valence shell electron pair repulsion theory and all the advanced methods of quantum chemistry.
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