The successive ionization energies of an unknown element are given as , , , and . Which of the follo — Periodic Table and Periodicity Chemistry Question

💡 Solution & Explanation

A massive, sudden jump in successive ionization energy occurs between $IE_2$ ($195 \text{ kcal/mol}$) and $IE_3$ ($556 \text{ kcal/mol}$). This indicates that the third electron is being removed from a highly stable, completely filled noble gas inner core. Thus, the neutral element must have exactly 2 valence electrons, matching the alkaline earth metal configuration $1s^2 2s^2 2p^6 3s^2$.