Question

why the electron gain enthalpy of nitrogen is less than carbon??

Answer 1

electron affinity of nitrogen is lower(less negative ) than carbon.

or nitrogen has positive electron gain enthalpy.

First of all,

Just as energy required to remove an electron from an atom, energy is released when an electron is added to a neutral atom.This is called electron gain enthalpy.

ie,the enthalpy change when electron is added to an isolated gaseous atom.

in other words, electron gain enthalpy is the enthalpy change accompanying in the process

A (g) + e- (g) is A- (g) + released energy

Electron gain process may be exothermic or endothermic . For many elements ,energy is released when an electron is added to the atom and therefore , electron gain enthalpy is negative.

The magnitude of the electron gain enthalpy measures the ability of an atom to hold an additional electron . If an atom has more tendency to accept an electron, large energy will be released.Consequently, electron gain enthalpy will be highly negative.On the other hand , if an atom has less tendency to hold the electron, small amount of energy will be released, leading to a small negative value of electron gain enthalpy.

factors affecting electron gain enthalpy

1.nuclear charge: more negative as nuclear charge increase. This is due to greater attraction for the incoming electron,if the nuclear charge is high.

2.size of the atom : electron gain enthalpy become less negative with increase of the size of the atom of the element.

3. electronic configuration: The elements having stable configurations of half filled and completely filled valancies subshells show very small tendency to accept additional electron and thus electron gain enthalpies are less negativ