The first, second and third ionisation energies (E1, E2 and E3) for an element are 7 eV, 12.5 eV and — Periodic Table and Periodicity Chemistry Question

💡 Solution & Explanation

Step 1: Examine the differences between successive ionization energies: IE2 - IE1 = 5.5 eV, whereas IE3 - IE2 = 30 eV. Step 2: There is an exceptionally large energy jump between the second and third ionization energies, indicating that the third electron must be removed from a stable, filled inner shell core. Step 3: This indicates that the element has two valence electrons, making the +2 oxidation state highly stable.