where does the mass number go in isotopic notation
Mass number The mass number is written either after the element name or as a superscript to the left of an element's symbol. For example, the most common isotope of carbon is carbon-12, or 12C, which has 6 protons and 6 neutrons. The full isotope symbol would also have the atomic number (Z) as a subscript to the left of the element symbol directly below the mass number: 12 6C.[2] This is technically redundant, as each element is defined by its atomic number, so it is often omitted.