Question

Explain the following observations:

(i) With the same d-orbital configuration (d4) Cr2+ ion is a reducing agent while Mn3+ ion is an oxidising agent.

(ii) Cu+ ion is not stable in aqueous solutions.

(iii) Among the 3d series of transition elements, the largest number of oxidation states are exhibited by manganese.

Answer 1

(i) Cr3+ is stable because of half filled t2g configuration. Mn3+ changes to Mn2+ to get stable half filled d-orbital.

(ii) Cu+ ion undergoes disproportionation reaction in aqu.solution.

(iii) The largest number of oxidation states are exhibited by manganese because it has highest number of unpaired electrons.