valence

n. chemical parameter related to the external electric charge of an atom or compound which gives an indication of its combining capacity (Chemistry)

Valence in molecules, atoms, or subatomic particles:valence in chemistryvalence bond theory in chemistryvalence shell in chemistryvalence band in physics valence quarks in particle physics Valence in other sciences:valence in linguistics, Valence (psychology) (and neuroscience) refers to the emotional value associated with a stimulus; e.g., a familiar face can have positive valence.the degree (or valency) of a vertex in graph theory (mathematics)univalent function in mathematicsValence is the name of several communes of France:Valence, préfecture (capital) of the Drôme départementValence, in the Charente départementValence, in the Tarn-et-Garonne département
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n. Valence, city in France

n. valence, chemical parameter related to the external electric charge of an atom or compound which gives an indication of its combining capacity (Chemistry)

(n.)
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.
  

The number of hydrogen atoms that typically bond to an atom of an element. For example, in H2O, oxygen has a valence of 2; carbon in CH4 has a valence of four.