What is a subscript in a chemical formula?

The subscript represents the number of atoms of an element in a compound. The number is found to the lower right of the element's symbol.

The subscript of one is never written because it is considered to be understood. In a compound, the subscript appears after the end parentheses. For instance, in Ca(NO3)₂, the two is the subscript. It represents that two nitrates are present in the compound calcium nitrate.

Subscripts cannot be changed in a compound's chemical makeup. If the subscript is changed, it is no longer the chemical it originally represented. When dealing with polymers, the subscript can sometimes be a letter.