Nitrogen, phosphorous, arsenic : Position(P.T)


source :

Nitrogen(N), Phosphorus(P), Arsenic (As), Antimony (Sb) & Bismuth (Bi)  are present in 5th A or 15th group of periodic table. These are the elements of nitrogen family. These are p-block elements.

General characteristics:

1. Electronic configuration:

7N : 1s2, 2s2, 2p3

15P: 1s2, 2s2, 2p6, 3s2, 3p3

33As: 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p3

51Sb: 1s2,2s2,2p6,3s2,3p6,4s2,3d10,4p6,5s2,4d10,5p3

83Bi: 1s2,2s2,2p6,3s2,3p6,4s2,3d10,4p6,5s2,4d10,5p6,6s2,4f14,5d10,6p3.

The configuration of outermost shell is ns2,np3.

2. Atomic radius:

Atomic and ionic radius increases on moving down the group because number of shell increases. Radius of anion is always greater than its neutral atom.

N 3- > N

while radius of cation is always smaller than its neutral atom.

Bi+++ < Bi

3. Ionization potential:

I.P decreases on moving down the group because atomic radius increases. I.P. is inversely proportional to atomic radius.

4. Metallic and non-metallic character:

Metallic character increases and non-metallic character decreases on moving down the group because electropositive character increases.

N,P (non-metal) , As, Sb (metalloids), Bi (metal)

5. Oxidation state and valency:

Normal valency of these element is  3. Except nitrogen other elements of this group also show valency of 5 because N atom doesn’t have d-orbital while other elements of this group have vacant d-orbital of appropriate energy.

Question : Phosphorus form PCl5 & PCl3 while nitrogen form only NCl3 or NF3?

7N : 1s2, 2s2, 2p3


15P: 1s2, 2s2, 2p6, 3s2, 3p3



Nitrogen  form NCl3 because it does not have d-orbital while P form PCl3 and PCl5 both because P can extend its  octet due to presence of empty d-orbital.

6. Tendency to form multiple bond:

Nitrogen may form -, = or ≡ bond with nitrogen itself or other elements such as C, S etc.

7. Allotropy :

Except Bismuth all other elements of this group show allotropy. Two allotropes of nitrogen are α- and β-nitrogen. Allotropes of phosphorus are white P, red P, black P, Scarlet P, violet P etc.