a. Chem. [f, TRI- + L. valēnt-em, pr. pple. of valēre to be worth.] Having the combining power of three atoms of hydrogen or other univalent element; combining with three atoms of a univalent element or radical.
1868. Fownes, Elem. Chem. (ed. 10), 251. Trivalent elements or Triads.
1876. Tilden, Chem. Philos., 143. The group PO4 is trivalent, and so it holds together the two atoms of sodium and one atom of hydrogen in one molecule.
1880. Cleminshaw, trans. Wurtz’ Atom. The., 260. The ammonia type [represented] the combination of a trivalent atom with three univalent atoms.
1888. Muir & Morley, Watts’ Dict. Chem., I. 524. The atom of B [Boron] is trivalent in gaseous molecules.
Hence Trivalence, the quality of being trivalent.
1888. Athenæum, 21 July, 102/2. The trivalence of the metals of the aluminium group.
