The chemical notation used to represent the elements and their composition in a molecule is known as [[1]].

A molecular formula contains symbols of chemical elements and their composition as subscripts. 

The chemical symbol implies the type of element present in definite proportions. For writing a chemical formula we must be aware of the total charge and elements present in it. 

For example: water contains two hydrogens and one oxygen per molecule. Its chemical formulae is ${\mathrm{H}}_2\mathrm{O}$.