Chemistry - PERIODIC TABLE Question with Solution | TestHub

The electron affinity (EA) is the energy released when an electron is added to a neutral atom in the gaseous state. Generally, EA increases across a period and decreases down a group.

Option 1: $1s^{2}2s^{2}2p^4$ (Oxygen, O)

Option 2: $1s^{2}2s^1$ (Lithium, Li)

Option 3: ${}_{36}[Kr]4d^{10}5s^1$ (Rubidium, Rb)

Option 4: $1s^{2}2s^{2}2p^{6}3s^{2}3p^4$ (Sulfur, S)

Oxygen and Sulfur are in the same group (Group 16). Sulfur is below Oxygen in the periodic table. While EA generally decreases down a group, the EA of elements in the second period (like Oxygen) is often lower than expected due to electron-electron repulsion in the small 2p orbitals. Sulfur, being larger, experiences less electron-electron repulsion when an electron is added to its 3p orbital, leading to a higher electron affinity than Oxygen. Lithium and Rubidium are alkali metals (Group 1) and have very low electron affinities.

Therefore, Sulfur (Option D) has the maximum electron affinity among the given configurations.