5 public questions tagged with this topic.
Electron affinity is the energy change for X + e⁻ -> X⁻. Cl has the highest electron affinity due to its balance of size and nuclear charge, though F’s electron gain enthalpy is less negative due to repulsion.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Electron Gain Enthalpy and Electronegativity and Valency
Electron affinity decreases down group 17 due to increasing size and reduced nuclear attraction. I (period 5) has the lowest value among F, Cl, Br, and I.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Electron Gain Enthalpy and Electronegativity and Valency
Electron affinity increases across period 2. F has the highest electron affinity in period 2 (Li, Be, N, F), though less than Cl (period 3) due to electron repulsion in its compact 2p orbitals.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Electron Gain Enthalpy and Electronegativity and Valency
Electron gain enthalpy becomes more negative across a period and less negative down a group. Among O, S, F, and Cl, Cl (group 17, period 3) has the most negative value due to its high effective nuclear charge and smaller size than S.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Electron Gain Enthalpy and Electronegativity and Valency
Electron affinity decreases down group 17, with Cl highest due to optimal size and nuclear charge, followed by F (anomaly due to repulsion). Order: Cl > F > Br > I.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Electron Gain Enthalpy and Electronegativity and Valency
