The d and f Block elements – Solutions

1. Why are Mn²⁺ compounds more stable than Fe²⁺ compounds towards oxidation to the +3 state?

Solution

Mn²⁺ compounds are more stable than Fe²⁺ compounds towards oxidation to their + 3 state, due to half filled d-orbitals in Mn²⁺ , while Fe²⁺ gains half filled d-orbitals by losing one electron by getting oxidised to Fe³⁺ . Hence , Mn²⁺ is not oxidised easily to Mn³⁺ .

Fe²⁺   Fe³⁺  +   e⁻

3d⁶    →         3d⁵

(Unstable)        (Stable)

Mn²⁺  →    Mn³⁺ + e⁻

3d⁵      →    3d⁴