How can I make formulas in chemistry?

In order to write a chemical formula the following Steps should be taken in account.

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 ion is one, the bracket is not required. For example – NaOH.

 

Whenever applicable, write simple ratios of the valencies.

The final formula must be written without any sign of the charge.

Hydrogen sulphide contains the elements hydrogen and sulphur.

(a) Write the symbol.                                                                                              H         S

(b) Write the valency of each element                                                                 1          2

(c) Interchange the valencies of the elements and write as the subscript.  H₂       S₁

(d) Write them close together and ignore ‘1’ to obtain the formula.                H₂S