What should one ensure while writing a chemical formula?

A Chemical formula is a symbolic representation of a molecule’s composition. 

It indicates the elements that are present in the compound and the ratio of these elements in the compound.

In order to write a chemical formula, the following steps should be ensured is done correctly: 

Step 1- Write down the symbols of the elements/ions, which combine to form a molecule of the compound, side by side. (While writing the formula of a compound containing a metal and a non-metal, the symbol of the metal is written first followed by that of the non-metal.)

Step 2- Write the valency of each element /ion.

Step 3- Interchange the valencies of the elements /ions and write as the subscript. Write them close together and ignore ‘1’ to obtain the formula.

Step 4- The radical/polyatomic ions must be written in brackets before the subscript is written. In case the number of polyatomic ions is one, the bracket is not required. For example – NaOH.