Isotope "nuclide", and is still sometimes used in contexts where "nuclide" might be more appropriate, such as nuclear technology and nuclear medicine. An isotope and/or nuclide is specified by the name of the particular element (this indicates the atomic number) followed by a hyphen and the mass number (e.g. helium-3, helium-4, carbon-12, carbon-14, uranium-235 and uranium-239). When a chemical symbol is used, e.g. "C" for carbon, standard notation (now known as "AZE notation" because "A" is the mass number, "Z" the atomic number, and E for element) is to indicate the mass number (number of nucleons) with a superscript at the
Atomic mass unit of carbon-12 in 0.012 kg of carbon-12. This can be expressed mathematically as Molecular masses of proteins are often expressed in kilodaltons (kDa or kD). For example, a molecule of a protein with molar mass has a mass of 64 kDa. In research and commerce, the degree of polymerization of synthetic polymers is conventionally expressed in daltons. The US Supreme Court based a major precedent of appellate law on a disputed case of counting daltons for a molecular distribution. Atomic mass unit The unified atomic mass unit or dalton (symbol: u, or Da) is a standard unit of mass that