n. 原子价

[化] 化合价; 原子价

[医] 效价; 价(化合价,原子价)

Valence \Va"lence\, n. [From L. valens, -entis, p. pr. of valere
to have power, to be strong. See {Valiant}.] (Chem.)
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.

Note: The valence of certain elements varies in different
compounds. Valence in degree may extend as high as
seven or eight, as in the cases of iodine and osmium
respectively. The doctrine of valence has been of
fundamental importance in distinguishing the
equivalence from the atomic weight, and is an essential
factor in explaining the chemical structures of
compounds.

Valance \Val"ance\, n. [Perhaps fr. OF. avalant descending,
hanging down, p. pr. of avaler to go down, let down, descent
(cf. {Avalanche}); but probably from the town of Valence in
France.]
1. Hanging drapery for a bed, couch, window, or the like,
especially that which hangs around a bedstead, from the
bed to the floor. [Written also {valence}.]

Valance of Venice gold in needlework. --Shak.

2. The drooping edging of the lid of a trunk. which covers
the joint when the lid is closed.