Q.Give the electronic configuration of Mn^2+ and Cr^3+.

The electronic configurations of the ions are obtained from those of the neutral atoms Mn (Z=25) and Cr (Z=24) by removing the appropriate number of electrons, taking the 4s electrons out before the 3d. …

We must write the ground-state electronic configurations of the Mn^2+ and Cr^3+ ions.

Manganese (Mn), Z = 25: neutral atom configuration = [Ar] 3d^5 4s^2. To form Mn^2+, two electrons are removed. For transition metals, the 4s electrons are lost before the 3d electrons, so both 4s electrons are removed: Mn^2+ = [Ar] 3d^5. (This half-filled 3d^5 configuration is extra stable.) …