Question

Comment on statement F>Cl>Br>I of electron gain enthalpy becoming less negative

Answer 1

Correct question :- Comment on statement Cl>F>Br>I of electron gain enthalpy becoming less negative.

Solution

$\boxed{\green{\textsf{Electron Gain Enthalpy}}}$

The amount of energy released in KJ/mol when an electron is added to the outermost shell of an atom.

Factor affecting electron gain enthalpy :-

• Effected nuclear charge :- More the nuclear charge, more the electron is attracted.Thus, more the electron gain enthalpy.

• Size of the atom :- Lesser the size, more the effective nuclear charge and thus higher electron gain enthalpy.

• Stable configuration :- Noble gases have stable configuration and thus, they have positive electron gain enthalpy. It implies that it needs energy to add electrons to such atom. Nitrogen too has positive electron gain enthalpy

Explanation

• Down the group, atomic radius increases and hence,electron gain enthalpy decreases.

• However,fluorine has lesser electron gain enthalpy than chlorine.It is because it has smaller size due to which electron is repelled more strongly.

Thus,it should follow the order Cl > F >Br >I

Answer 2

Answer:

The electron gain enthalpy values of halogens become more negative in the order F>Cl>Br>I. ... However the electron gain enthalpy of F is less negative than of Cl because of its small size. The additional electron in case of F will be added to the 2p orbital while in case of Cl it will go in the 3p orbital.