Question

Explain any four factors which influence the electron affinity (Electron Gain Enthalpy)

Answer 1

Electron Gain Affinity: It is defined as the energy liberated when an electron is added to it's neutral gaseous atom.
Electron Affinity is also defined as electron gain enthalpy.
Generally electron Affinity decreases as we go down in a group but increases along a period from left to right.

Factors Affecting electron Affinity:
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1. Nuclear Charge:
Greater the nuclear charge . Greater will be the attraction for incoming electron.Due to thus , larger will be the value of electron Affinity.
Example: Na and Cl
As nuclear charge is more for Cl , so greater Electron Affinity for Cl.

2. Atomic Radius:
More radius , less is the electron Affinity. As distance between nucleus and incoming electron increases.
Example: Li and Na
sodium has more atomic radius hence less electron Affinity.

3. Stable electron configuration:

Stable the configuration of atom lesser will be it's tendency to accept an electron and hence lower the value of electron Affinity.
Example: O and N
O electronic configuration: 1s2 2s2 2p4
Nitrogen : 1s2 2s2 2p3
here Nitrogen is more stable, hence more electron Affinity value.

4. Screening Effect:
More the shells with electrons between the nucleus and the valence shell.Less will be nuclear cbarge. Thus, decreases electron Affinity.
Example:
Li and Cs
Cs has less electron Affinity Value.

Answer 2

electron affinity :- the enthalpy change accompanying the reaction when an electrons is added to a neutral gaseous atom is known as electron gain enthalpy .and any elements have this property it means they have electron affinity .

electron affinity depends upon :-
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1) size of the elements :- if any elements have big size then , it's tendency of accepting electrons is low .
hence,
electron affinity inversely proportional to size of elements

2) effective nucleur charge (Zeff) :-
effective nucleur charge is the charge for which neuclus held with electorns .
if effective nucleur charge is high it means we easily add a electrons in orbit of atoms hence, electrons affinity will be high when effective nucleur charge is high .

e.g electorns affinity directly proportional to effective nucleur charge .

3) electronic configuration :- usually half or full -filled electronic configuration give positive electron affinity . because , half flled or full -filled electronic configuration assume stable.

4) electron affinity also depends upon we give electron in which subshell (e.g s, P , d , f )
generally electron affinity of S >p> d>f

because we know, S-subshell exist nearest of nucleus then P , d , and last f
so , electron gaining capacity gradually decrease .