# Why is the atomic mass of the sodium atom "23 amu"?

And by DEFINITION, sodium has 11 protons, massive, charged, nuclear particles, the which number defines the element as sodium, i.e. $Z = 11$, and most nuclei contain 12 neutrons, massive neutral, nuclear particles.
And so we gets the isotope ""^23Na....which is 100% abundant to a first approximation....How many electrons does a NEUTRAL sodium atom contain?