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Question: Answered & Verified by Expert
\( M n^{2+} \) compounds are more stable than \( F e^{2+} \) compounds towards oxidation to their \( +3 \) state,
because
Chemistryd and f Block ElementsKCETKCET 2016
Options:
  • A \( M n^{2+} \) is more stable with high \( 3 r d \) lonisation energy.
  • B \( M n^{2+} \) is bigger in size.
  • C \( M n^{2+} \) has completely filled d-orbitals.
  • D \( M n^{2+} \) does not exist.
Solution:
1485 Upvotes Verified Answer
The correct answer is: \( M n^{2+} \) is more stable with high \( 3 r d \) lonisation energy.
Electronic configuration of \( M n^{2+} \) is \( 4 s^{0} 3 d^{5} \) :
\begin{array}{|l|l|l|l|l|}
\hline \( 1 \) & \( 1 \) & \( 1 \) & \( 1 \) & \( 1 \) \\
\hline
\end{array}
Electronic configuration of \( F e^{2+} \) is \( 4 s^{0} 3 d^{6}: \)
\begin{array}{|ll|l|l|l|l|}
\hline \( 1 \) & \( \downarrow \) & \( 1 \) & \( 1 \) & \( 1 \) & \( 1 \) \\
\hline
\end{array}
Since, in \( M n^{2+} \) the d-orbital is completely half-filled, therefore, its third ionization energy is high and hence, it stable
towards oxidation to \( +3 \) oxidation states, whereas, in \( \mathrm{Fe}^{2+} \), the d-orbital is partially filled and only one electron is paired,
therefore, its third ionization energy is lower than \( \mathrm{Mn}^{2+} \) ion and hence, it is less stable towards \( +3 \) oxidation states.

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