The mass number of an atom is determined by the number of protons and neutrons. Calculate the mass number of a Sodium (Na) atom if the number of neutrons in it are 12.
Is atomic mass the sum of the number or mass of protons and neutrons.
If it is sum of number , then why is it called atomic MASS
And if it is sum of mass then how do we know the no of neutrons and proton sin the atom.