(a) Why are Mn^(2+) compounds more stable than Fe^(2+) towards oxidation to their +3 state? (b) What are interstitial compounds ? Why are such compounds well-known for transition metals? (c) Write electronic configuration of Pm^(3+).

(a) Why are Mn^(2+) compounds more stable than Fe^(2+) towards oxidati

1.	(a) Why are Mn^(2+) compounds more stable than Fe^(2+) towards oxidation to their +3 state? (b) What are interstitial compounds ? Why are such compounds well-known for transition metals? (c) Write electronic configuration of Pm^(3+).
Answer» Solution :(a)`Mn^(2+) (3d^(5))` - exactly half FILLED and extra stable and has HIGH 3rd ionisation enthalpy `FE^(2+) (3d^(6))` can lose electron easily to get `Fe^(3+) (3d^(5))` i.& extra stable configuration. (b) In such compounds, the small atoms such as H, C, B, N etc. occupy interstitial sites in their lattices eg. Tic, `TiH_(2), Fe_(3)H` Steel etc. Such compounds are called interstitial compounds. Transition metals form such compounds because they can take up small atoms of C, H, B, Netc. in their interstitial sites in their lattices. (c)`Pm^(3-1)(61-3=58e)` `1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)3d^(10)4s^(2)4p^(6)4d^(10)5s^(2)5p^(6)4f^(4)` in `[Xe]_(54)4f^(4)`