redox potential

The tendency of a reducing agent to lose electrons (or an oxidizing agent to gain electrons) as measured against a known standard, usually hydrogen. By convention the reaction is written in the direction oxidant + ne^- ↔ reductant where η is the number of electrons transferred. Compounds with a redox potential more positive than that of hydrogen tend to donate electrons to H⁺; compounds with a more negative redox potential tend to accept electrons from H₂.