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

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

source : chemicool.com

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 PCl_{5 &} 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.