Phosphorous acids can have acidic protons bound to
oxygen atoms and nonacidic protons which are bonded
directly to the phosphorus atom. Although many oxyacids
of phosphorus are formed, only six are important
and three of them, hypophosphorous acid, phosphorous
acid, and phosphoric acid are the particularly important
ones. Two other “peroxy”-acids are included since there
properties have been described in the literature.
