Atomic Mass Unit

The individual masses involved involved in nuclear reactions are tiny. The mass of a proton is
\[1.672621 \times 10^{-27} kg\]
, almost the same as the mas of a neutron. This is not a convenient mass unit. We define a convenient mass unit as one twelfth the mass of a Caron- 12 atom, called the atomic mass unit, labelled
\[1 u=\frac{1}{12} (mass \: of \: {}^{12}_6C)=1.660539 \times 10^{-27} kg\]

In terms of the atomic mass unit the mass of a proton is

The mass of a neutron is
\[1.008665 u\]

The mass of an electron is
\[0.000549 u\]