Amu (atomic mass unit) One atomic mass unit is defined as exactly 1/12 mass of an atom of carbon-12. We know
experimentally that the mass of an atom of carbon-12 is 1.9926 x 10g. It follows that 1amu = 1.6605 x
10-g. The mass of any other type of atom in grams can be expressed in atomic mass unit by using this
relation as a conversion factor.