Why is `+2` oxidation state of manganese quite stable while the same is not true for iron?`[Mn=25,Fe=26]`.

Answer

To understand why the +2 oxidation state of manganese (Mn) is quite stable while that of iron (Fe) is not, we can analyze their electronic configurations and the stability associated with them.

### Step-by-Step Solution:

1. **Identify the Atomic Numbers and Electronic Configurations**:
- Manganese (Mn) has an atomic number of 25. Its electronic configuration is:
\[ \text{Mn: } [\text{Ar}] 3d^5 4s^2 \]
- Iron (Fe) has an atomic number of 26. Its electronic configuration is:
\[ \text{Fe: } [\text{Ar}] 3d^6 4s^2 \]

2. **Determine the Oxidation State**:
- When manganese loses 2 electrons to achieve the +2 oxidation state, its electronic configuration becomes:
\[ \text{Mn}^{2+}: [\text{Ar}] 3d^5 \]
- When iron loses 2 electrons to achieve the +2 oxidation state, its electronic configuration becomes:
\[ \text{Fe}^{2+}: [\text{Ar}] 3d^6 \]

3. **Analyze the Stability of the Electronic Configurations**:
- The configuration of Mn²⁺, which is 3d⁵, is half-filled. Half-filled subshells are known to be particularly stable due to symmetry and exchange energy.
- The configuration of Fe²⁺, which is 3d⁶, is not half-filled. While it is stable, it does not have the same level of stability as a half-filled subshell.

4. **Conclusion on Stability**:
- The half-filled 3d subshell in Mn²⁺ provides extra stability, making the +2 oxidation state of manganese quite stable.
- In contrast, the 3d⁶ configuration of Fe²⁺ lacks this extra stability, which is why the +2 oxidation state of iron is not as stable as that of manganese.

### Final Answer:
The +2 oxidation state of manganese is stable due to its half-filled 3d subshell (3d⁵), which provides extra stability. In contrast, iron's +2 oxidation state (3d⁶) does not benefit from this stability, making it less stable than manganese's +2 state.

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