Atomic mass in 12 grams of the carbon isotope C-12. The number of atoms in a mole is called Avogadro's number, the value of which is approximately 6.022 × 10. One mole of a substance always contains almost exactly the "standard atomic weight" or "molar mass" of that substance; however, this may or may not be true for the "atomic mass," depending on whether or not the element exists naturally in more than one isotope. For example, the standard atomic weight of iron is 55.847 g/mol, and therefore one mole of iron as commonly found on earth has a mass of 55.847
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