MCQ Detailed View

Electron affinity (EA) is the energy change that occurs when an atom gains an electron to form a negative ion. It is a key periodic property of elements, helping to explain reactivity, chemical bonding, and trends in the periodic table.

Among the halogens—fluorine, chlorine, bromine, and iodine—the electron affinity varies due to atomic size and electron repulsion. Chlorine has the maximum electron affinity, even higher than fluorine. This is because chlorine has a smaller atomic size compared to Br and I, allowing the added electron to experience stronger nuclear attraction.

Fluorine, despite being the smallest halogen, has slightly lower electron affinity than chlorine due to increased electron-electron repulsion in its compact 2p orbitals, which partially offsets the energy released when gaining an electron. Bromine and iodine have lower electron affinities because their larger atomic radii reduce the effective nuclear attraction on the added electron.

Electron affinity trends generally increase across a period and decrease down a group. In the halogen group, chlorine is the most energetically favorable for accepting an extra electron. Understanding electron affinity helps predict oxidizing strength, reactivity in halogen compounds, and bond formation in inorganic molecules.

Chlorine’s high electron affinity explains its strong oxidizing properties and tendency to form Cl⁻ ions in chemical reactions. This concept is fundamental in inorganic chemistry for understanding redox reactions, halogen chemistry, and periodic trends.

Recognizing why chlorine, rather than fluorine, has the maximum electron affinity illustrates the importance of atomic structure, repulsion, and energy changes in chemical behavior.