ABSTRACT
The electrochemistry of nitrogen is enriched by the fact that this element is known to exist in at least 10 different oxidation states, one of which is non-integer. N2 is thermodynamically stable under nearly all the potential-pH conditions that are necessary for the stability of H2O. Thus N2 and H2O can coexist readily in nature and N2 is the most common nitrogen compound on the surface of the earth. The reactivity of the various forms of nitrogen appears to be controlled primarily by kinetics. Thus predictions of thermodynamic reactivity among the nitrogen compounds are often rendered invalid by the charge transfer kinetics associated with the change in oxidation state. The important compounds of the various oxidation states of phosphorus range from -3 to +5. Phosphorus exists in three main allotropic forms: white, red, and black. Arsenic exists in three allotropic forms: yellow, black, and metallic gray forms.
