Question

Which of the following elements has the maximum electron affinity?

• A. F
• B. Cl
• C. Br
• D. I

Answer 1

The correct option is B

Cl

Electron gain enthalpy $\alpha$ $\frac{1}{AtomicSize}$
Electron gain enthalpy $\alpha$ Effective nuclear charge
Electron Affinity term can also be used to measure the ability of an atom to gain an electron. If energy is released when an electron is added to an atom, the electron affinity is taken as positive, contrary to thermodynamic convention.
Then, I > Br > Cl > F [Atomic Radius]
$\Rightarrow$ It should be F > Cl > Br > I [EA]
But as we know, electron gain enthalpy $\alpha$$\frac{1}{AtomicSize}$
Therefore, F > Cl, but, fluorine is very small, therefore electron density is high and an increased electronic repulsion makes the addition of an electron to fluorine less favorable than that in the case of chlorine. Therefore, the order will be Cl > F > Br > I [EA].
$\Rightarrow$ Cl has maximum electron affinity.