WHAT IS THE ATOMICITY OF AN ELEMENT?HOW IS IT USEFUL IN WRITING THE CHEMICAL FORMULA OF AN ELEMENT?
Atomicity: The total number of atoms of element present in one molecule of that element or substance, is called as atomicity of that element/substance.
The atomicity may be different depending on no. of atoms as; monoatomic for 1, diatopmic for 2 etc.
For example: In He or Ne, they are inert gases which do not combines and so they are monoatomic ; He, Ne
In, Oxygen: two atoms combine to form a molecule so its diatomic;O2
In Ozone ; Triatomic ;O3
In Sulphur: Polyatomic ; S8
In case of HCl; the atomicity is 2 (diatomic)as it cis made up of 1/2 molecule of Chlorine and 1/2 molecule of hydrogen.
So, if atomicity of H anAd Cl is 2 then atomicity of HCl will also be two.
It is important to explain the composition of elements in each compound or molecule.