Which of the following transformation least energy is required? — Periodic Table and Periodicity Chemistry Question

💡 Solution & Explanation

Step 1: The process representing the removal of an electron from a gaseous anion is the reverse of electron gain; the energy required is equivalent to the electron affinity of the neutral atom. Step 2: Compare the electron affinities of Fluorine, Phosphorus, Sulfur, and Chlorine. Phosphorus has a stable, half-filled p^3 configuration (1s2 2s2 2p6 3s2 3p3), giving it a very low electron affinity. Step 3: Since Phosphorus has the lowest electron affinity, its anion P^- holds the extra electron most loosely and requires the least energy to be oxidized to neutral P. Thus, option (b) is correct.