Electronic configuration of nitrogen (atomic number 7) :
Shells: K L
Electrons: 2 5
Electronic configuration of phosphorus (atomic number 15) :
Shells: K L M
Electrons: 2 8 5
The element nitrogen will be more electronegative because of the smaller size of its atom compared to phosphorus. Since, nitrogen has a smaller atomic radius than phosphorus, the attraction of its nucleus towards the incoming electron is more than phosphorus. Therefore, nitrogen accepts electrons more easily.