JEE Main · 2023 · 01 Feb 2023 · Shift 2 · Classification of Elements and Periodicity

Electron gain enthalpy is a negative quantity, and a more negative value means greater energy release on adding an electron. Down a group it generally becomes less negative as size increases, but the first member is anomalous because its small, compact shell suffers extra electron–electron repulsion; hence chlorine is more negative than fluorine and sulphur is more negative than selenium. The comparisons for the halogen pair and for the heavier chalcogen pair respect this trend, as does the tellurium–polonium pair. The statement claiming selenium to be more negative than sulphur reverses the true order and is the incorrect statement.