Question

Which arrangement represents the correct order of electron gain enthalpy (with negative sign) of the given atomic species ?

• A. $F<Cl<O<S$
• B. $O<S<F<Cl$
• C. $Cl<F<S<O$
• D. $S<O<Cl<F$

Answer 1

The correct option is B $O<S<F<Cl$

• $O$ has exceptionally smaller value of electron affinity $(–141kJmo{l}^{-1})$ due to smaller atomic size than sulphur (weaker electron-electron repulsion in $3p$-subshell).
• There is more interelectronic repulsion in $2p$-subshell of fluorine than chlorine $\left(3p\right)$.
• So extra electron will be added easily in $3p$-subshell of chlorine as compared to $2p$-subshell of fluorine.