Concept:Ionization energy generally increases across a period, but anomalies occur when electrons are removed from highly stable, fully filled subshells.
Formula:$$ \text{Mg: } [\text{Ne}] \ 3s^2 \quad vs \quad \text{Al: } [\text{Ne}] \ 3s^2 \ 3p^1 $$
Solution:- Magnesium has a completely filled \( 3s \) subshell, which offers extra stability and requires more energy to disrupt.
- Aluminum's outermost electron resides alone in the \( 3p \) subshell.
- This \( 3p \) electron is higher in energy and partially shielded from the nucleus by the full \( 3s \) orbital, making it easier to remove.
Why other options are incorrect:- Option B, Option C, Option D: These are either consequences or simple factual statements that do not explain the quantum mechanical reason for the anomaly.
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