The first four I.E. values of an element are 284, 412, 656 and 3210 kJ mol-1. The number of valence — Periodic Table and Periodicity Chemistry Question

💡 Solution & Explanation

Step 1: Examine the sequence of ionization energies: IE1 = 284, IE2 = 412, IE3 = 656, and IE4 = 3210 kJ mol^-1. Step 2: Locate the biggest jump in energy. The jump from IE3 (656) to IE4 (3210) represents a massive, nearly 5-fold increase, showing that the fourth electron is removed from a highly stable inner shell. Step 3: Since three electrons can be removed relatively easily before encountering this massive jump, the element must have exactly 3 valence electrons.