what is atomic mass unit?
The unified atomic mass unit (u) or Dalton ( Da) is a unit that is used for indicating mass on an atomic or molecular scale. One Da is approximately equal to the mass of one proton or one neutron. An atomic mass unit or amu is one twelfth of the mass of an unbound atom of carbon-12. This means that a carbon-12 atom has the atomic mass of 12 daltons. Mass is the property which reflects the quantity of matter within a sample.