The Nitrogen Family

Elements in 15th group are known as ‘The Nitrogen Family’. The family includes the following elements:

Element Atomic Number Electronic Configuration Character
N 7 1s22s22p3 Non-metal
P 15 1s22s22p63s23p3 Non-metal
As 33 1s22s22p63s23p6 3d104s24p3 Metalloid
Sb 51 1s22s22p63s23p6 3d104s24p64d105s25p3 Metalloid
Bi 81 1s22s22p63s23p6 3d104s24p64d10 4f145s25p65d106s26p3 Metal

Occcurence : Nitrogen – Nitrogen is found in the molecular form in the atmosphere. It comprises 75% by mass and 78% by volume of the atmosphere. It is also found in Earth’s crust in the form of Chile Saltpetre(Sodium Nitrate : NaNO3) and Indian Saltpetre(Potassium Nitrate-KNO3). In the form of protein, Nitrogen is also available in plants and animals.

Reactivity towards oxygen : Group 15 elements form oxides by reacting with oxygen of the form E2O3, E2O4 and E2O.Ex: N2O3, N2O4, P2O5, As2Oetc. 

Key Points : 1. Among oxides the acidic nature increases with increase in the oxidation state.

2. The acidic nature also increases with increase in the percentage of oxygen.

3. In the group, the acidic nature decrease with increase in atomic number due to increase in the metallic character.

E2O3 Type Oxides of


Nitrogen & Phosphorus

Purely acidic

Arsenic & Antimony




4. The stability of oxides decreases down the group.

Reactivity towards Hydrogen : Group 15 elements react with Hydrogen to form hydrides of the form EH3. Ex : NH3 (Ammonia), PH3 (Phosphine), BiH3 (Bismuthine) etc.

Key Points : 1. The thermal stability decreases down the group because the tendency to form covalent bond decreases as the size of atoms increases which leads to increase in the metallic character.


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