Nitrogen and phosphorus both have half filled orbitals,then why is electron gain enthalpy of phosphorus negative while nitrogen is positive?
Dear User,
The electron gain enthalpy is +ve i.e. energy is required for the process and therefore it is endothermic. High electron gain enthalpy of Nitrogen means that more energy is required to add an electron to N than in P.
This is due to small size of N as compared to P. The addition of one more extra electron to N atom produces high repulsion between the electrons already present and the electron being added.Although this repulsion will also be present in case of P but will be greater in N. Due to the increased electron-electron repulsion, N show lesser tendency to attract an electron towards them to form N- and hence the electron affinity value of N will be more positive as compared to P.
The electron gain enthalpy is +ve i.e. energy is required for the process and therefore it is endothermic. High electron gain enthalpy of Nitrogen means that more energy is required to add an electron to N than in P.
This is due to small size of N as compared to P. The addition of one more extra electron to N atom produces high repulsion between the electrons already present and the electron being added.Although this repulsion will also be present in case of P but will be greater in N. Due to the increased electron-electron repulsion, N show lesser tendency to attract an electron towards them to form N- and hence the electron affinity value of N will be more positive as compared to P.