In a chemical formula, subscripts indicate what?

• A. The charge of the element
• B. The total molecular weight of the compound
• C. The number of atoms of the element to the left
• D. The color of the element in the diagram

Answer: (C)

Subscripts tell you how many atoms of each element are present in one molecule. They come after the element symbol and refer to that element on the left—for example, in H2O there are two hydrogens and one oxygen (the oxygen has no subscript, which means one atom). Subscripts do not indicate charge (that’s shown as a superscript) and they don’t set the color or the molecular weight directly—the weight comes from atomic weights multiplied by those counts. If a formula uses parentheses, the subscript after the parentheses multiplies all the atoms inside.