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(v) Reducing nature, , M(s)—>M(g) sublimation enthalpy, M(g)—M* (g)+e7 ionization enthalpy, M* (g)+H,O-—M" (aq) hydrationenthalpy, , » The tendency of an element to lose an electron is measured by its, oxidation potential. More the value of oxidation potential of an, element stronger will be it’s reducing character., , >» The alkali metals have a low value of ionization energy and high, values of oxidation potential. They have a strong tendency to lose, electrons and act as good reducing agents., , >» Among all the alkali metals, Li is the strongest and Na is the weakest, reducing agent. (Li > Cs > Rb > K > Na), , » The reducing character increases from Na to Cs., , » Li, although, has the highest lonization energy, yet it's the strongest, reducing agent. With the small size of its ion, Li has the highest, hydration enthalpy which accounts for its High oxidation potential, value and its high reducing power., , » The alkali metals have a low value of ionization energy which, decreases down the group and so can easily lose their valence, electrons and thus act as good reducing agents., , (vi) Solutions of alkali metals in liquid ammonia: The alkali, metals dissolve in liquid ammonia giving deep blue solutions which, are conducting in nature., , Important characteristics of alkali metal solutions are:, , 1. The alkali metals dissolve in liquid ammonia and impart a deep blue _, colour to the solutions. And the colour is independent of the nature, of metal dissolved., , N, , The solution is electrically conducting, show strong reducing, properties and is paramagnetic., , . In concentrated solution, the blue colour changes to bronze colour, and become diamagnetic., , wo, , 4. If the reagents are pure and dry, Na solution in liquid NHs are stable, and can be preserved for several days., , Na = Na + @e, , Na* + xNHs = _ [Na(NHs),]*, Ammoniated cation, , e + yNHs = — [e(NHs)yl, , Ammoniated electron, Overall reaction: , M + (x+y)NHs + [M(NHs)J* + [e(NHs)y1, , Ammoniated cation Ammoniated electron, , » Alkali metals ionize into cations and electrons in liquid ammonia.