Mols et.al.

1
The Atomic Mass Unit (amu)
1
The atomic mass Standard
1?12
2
the mass of an atom of carbon-12
Recently, the designation amu has been changed to
the Dalton (D)
mass of 28Si atom ???????? mass of 12C atom
2.331411
Observed
Isotopic mass 28Si measured mass ratio x mass
of 12C
Thus
2.331411 x 12.0000 amu 27.9693