Hi!
I would like to get a clarification on the following:
The atomic mass (I do not want to use the term relative yet) is determined using the carbon - 12 scale in which carbon - 12 is arbitrarily set to have a mass of exactly 12. From this definition, it follows that all masses of all atoms must be relative, of course, to carbon - 12. I get it. This is where the term relative stems from. Good!
Now my first question is: is there such thing as an absolute mass of an atom? If not, does that mean that a carbon - 12 atom doesn't actually necessarily have 6 protons and 6 neutrons? Or, are these numbers (6 protons and 6 neutrons) arbitrarily assigned to a carbon - 12 atom?
Another thing: using the same scale, we set the mass of a proton to be equal to 1 u and that of a neutron to be equal also to 1 u. HOWEVER, The rest mass of a proton is 1.007276 u, and the rest mass of a neutron is 1.008665 u. How were these numbers determined? Are they relative to something? If yes, to what? 2 different values for the mass of the same subatomic particle would mean that there are 2 different mass scales?
Your contribution for clarification is appreciated.