Deduction of atomicity of elementary gas

Atomicity

Atomicity is the number of atoms of an element present in one molecule of that element. They can be monoatomic (He), diatomic (H₂), triatomic (O₃) and polyatomic (S₈). Homoatomic molecules have different atomicity.

Atomicity of Hydrogen and Chlorine

Let up take the example of the same reaction between hydrogen and chlorine. We saw earlier that;

Hence,

But 1 molecule of hydrogen chloride contains 1 atom of hydrogen and 1 atom of chlorine.

molecule of hydrogen = 1 atom of hydrogen

molecule of chlorine = 1 atom of chlorine

1 molecule of hydrogen = 2 atoms

1 molecule of chlorine = 2 atoms

Hence hydrogen and chlorine are both diatomic.

Atomicity of oxygen and nitrogen

One molecule of nitric oxide contains one oxygen atom and one nitrogen atom.

Thus,

molecule of nitrogen = 1 atom

molecule of oxygen = 1 atom

or, 1 molecule of nitrogen =2 atoms

1 molecule of oxygen = 2 atoms

Thus, both nitrogen and oxygen are diatomic.