Chemistry Lesson: Chemical Formulas

Chemical formulas are an expression of the types and numbers of atoms in a chemical compound. Writing chemical formulas involves element symbols and subscripts that indicate the number of each element present in the chemical formula. Parentheses are used to designate special groups within chemical formulas and chemical compounds. WATCH NEXT: LEARN CHEMISTRY FAST & EASY: COME SAY HI! What is a chemical formula in chemistry? Writing chemical formulas and interpreting chemical formulas begins with an understanding of the elements of the periodic table. These elements are represented by one or two letter symbols that are then combined with subscripts to indicate the number of each element present in the compound.