Oxidising Power Down Group 15

Question

Why does the stability of the +5 oxidation state decrease while that of the +3 state increases down Group 15 from phosphorus to bismuth?

RankGuru · Accepted Answer

The relative stability of oxidation states down Group 15 is explained by the inert pair effect. As the group is descended from phosphorus to bismuth, the outer ns^2 electron pair becomes increasingly reluctant to take part in bonding because of poor shielding by the intervening d and f electrons, which holds the s pair more tightly. Consequently the +5 state, which requires the use of all five valence electrons including the s pair, becomes less stable, while the +3 state, which uses only the three p electrons, becomes more stable down the group. This is why bismuth is most stable in the +3 state and BiF_5 is a strong oxidiser, whereas phosphorus readily shows +5. The option of increasing electronegativity is wrong, as electronegativity decreases down the group. The option of decreasing atomic size is false, since size increases. The option of increasing non-metallic character is incorrect, as metallic character increases down the group. This inert pair trend is a key JEE Advanced concept. Plausibility check: the strong oxidising power of Bi(V) compared with stable Bi(III) confirms the decreasing stability of the +5 state.

Oxidising Power Down Group 15

Select the correct option:

🔒 Solution Hidden from View

More p-block elements Practice Questions

Interhalogen compounds such as ClF_3 are generally more reactive than the individual halogens; what ...

Carbon monoxide is a highly poisonous gas; on what basis does it exert its toxic effect on the human...

Silicones are synthetic polymers with a repeating silicon-oxygen backbone; which property makes them...

Chlorine acts as a bleaching agent for cotton and paper; on what chemical principle does its bleachi...

In the structure of diborane, what unusual type of bonding holds the two boron atoms together throug...

Carbon shows a far greater tendency for catenation than silicon and the heavier members of Group 14;...

Among the allotropes of carbon, which one conducts electricity due to the presence of delocalised el...

Nitrogen exists as a diatomic gas with a very high bond dissociation enthalpy; what structural featu...

Why does nitrogen not form pentahalides such as NCl_5 whereas phosphorus readily forms PCl_5 in the ...

In the industrial Haber process for manufacturing ammonia, which set of conditions favours a high yi...

Why is white phosphorus far more reactive and toxic than red phosphorus despite both being allotrope...

Ozone acts as a powerful oxidising agent and readily decomposes to oxygen; what makes it thermodynam...

About This Question

Solution