Alkali metals are strong reducing agents, with lithium being the strongest of the group. The reducing power of an element can be determined by its standard electrode potential, which is a measure of the tendency of the element to lose electrons in aqueous solution. It is determined by three factors: (i) Sublimation enthalpy (ii) Ionization enthalpy and (iii) Enthalpy of hydration. Sublimation enthalpy of alkali metals is similar. Lithium has highest negative E^Ө value, which is –3.04V. Lithium has a small atomic size, the highest ionization enthalpy but it is compensated by its high hydration enthalpy. Due to this, the reducing power of lithium is highest in an aqueous solution.