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Webster 1913 Edition
Pentad
Pen′tad
,Noun.
[Gr.
πεντάσ
πεντάδος
, a body of five, fr. πέντε
five.] (Chem.)
Any element, atom, or radical, having a valence of five, or which can be combined with, substituted for, or compared with, five atoms of hydrogen or other monad;
as, nitrogen is a
. pentad
in the ammonium compoundsPen′tad
,Adj.
(Chem.)
Having the valence of a pentad.