One atomic mass unit, or amu, is equal to 1/12 the mass of a single carbon-12 atom. (To put that in perspective, a single carbon atom is roughly equal to 5.857 × 10^-26 ounces.) ...

The atomic mass is usually measured in atomic mass units (amu), where 1 amu is defined as one-twelfth of the mass of a carbon-12 atom. >Mass of Neutron = 1.008 amu ...

So, now instead of carbon listed as being 12.0107 atomic mass units with a measurement uncertainty of about 0.0008, it has an official atomic weight of [12.0096; 12.0116], ...

Then, in addition, atomic units usually leave unspecified whether or not a reduced mass is given unit value instead of the electron mass, or indeed whether other modifications have been made (see ...

THAT the intra-atomic charge of an element is determined by its place in the periodic table rather than by its atomic weight, as concluded by A. van der Broek (NATURE, November 27, p. 372), is ...