The first and second ionization energies of Potassium () are and respectively, while for Calcium () — Periodic Table and Periodicity Chemistry Question
Question
The first and second ionization energies of Potassium ($K$) are $419 \text{ kJ/mol}$ and $3052 \text{ kJ/mol}$ respectively, while for Calcium ($Ca$) they are $590 \text{ kJ/mol}$ and $1145 \text{ kJ/mol}$. Why is $IE_2$ of $K$ massively higher than $IE_2$ of $Ca$?
Answer: B
💡 Solution & Explanation
After losing one electron, $K^+$ achieves the stable Argon noble gas configuration ($3s^2 3p^6$). Removing a second electron requires breaking this highly stable core, costing immense energy. $Ca^+$ only loses its second $4s$ valence electron, which requires much less energy.
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