Element Symbols and Subscripts
Element symbols are one- or two-letter abbreviations for chemical elements, such as C for carbon, H for hydrogen, O for oxygen, and N for nitrogen. In a chemical formula, subscripts are used to indicate the number of atoms of each element in a molecule. For example, in the formula C3H7NO2, the subscript '3' indicates there are three carbon atoms, while '7' indicates seven hydrogen atoms.