Question

The ion $ C{r^{ + 2}} $ is reducing in nature while the same d-orbital configuration $ \left( {{d^4}} \right) $ , $ M{n^{ + 3}} $ is an oxidizing agent.

Answer 1

Hint: Chromium is the chemical element that can lose electrons and forms an ion $ C{r^{ + 2}} $ , Manganese is a chemical element that can lose two electrons and forms an ion $ M{n^{ + 3}} $ . Both of these ions have the same configuration, but one tries to attain half-filled $ {t_{2g}} $ orbitals and the other tries to attain half-filled d-orbital configuration.

Complete answer:
Chromium is an element with atomic number $ 24 $ , it has $ 4{s^1}3{d^5} $ valence configuration. It can lose two electrons and turn into an ion $ C{r^{ + 2}} $ with the valence configuration of $ 3{d^4} $ .
This chromium ion $ C{r^{ + 2}} $ is reducing in nature, which means itself undergoes oxidation and forms ion with $ 3{d^3} $ configuration, which has half-filled $ {t_{2g}} $ orbital.
Manganese is an element with atomic number $ 25 $ , it has $ 4{s^2}3{d^5} $ valence configuration. It can lose electrons and forms $ M{n^{ + 3}} $ with the valence configuration of $ 3{d^4} $ . This ion can act as an oxidizing agent which means it undergoes reduction to form an ion with half-filled d-orbital $ \left( {3{d^5}} \right) $ .
Thus, the ion $ C{r^{ + 2}} $ is reducing in nature while the same d-orbital configuration $ \left( {{d^4}} \right) $ , $ M{n^{ + 3}} $ is an oxidizing agent due to attain half-filled $ {t_{2g}} $ and half-filled d-orbital configuration.

Note:
Orbitals are classified into s, p, d, and f orbitals. d-orbital has the degeneracy of five, namely $ {d_{xy}},{d_{yz}},{d_{zx}},{d_{{x^2} - {y^2}}},{d_{{z^2}}} $ these five degenerate orbitals are divided into $ {t_{2g}} $ and $ {e_g} $ orbitals. The degenerate orbitals that come under $ {t_{2g}} $ are $ {d_{xy}},{d_{yz}},{d_{zx}} $ and the degenerate orbitals that comes under $ {e_g} $ are $ {d_{{x^2} - {y^2}}},{d_{{z^2}}} $ . Ions try to attain completely filled, half filled, or half-filled $ {t_{2g}} $ electronic configuration.