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.) ...

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], ...

Atomic Mass: The atomic mass of an atom is the sum of the protons and neutrons in its nucleus. It is expressed in atomic mass units (amu). For example, Carbon-12, ...

DISCUSSING the unit of atomic weight before Section A (Physics) at the meeting of the British Association in London on Sept. 28, Dr. F. W. Aston contrasted the point of view of the physicist and ...