An atom of a sodium has 11 proton, 11 electrons,12 neutrons. what is it atomic number? What is it mass number

please explain

the atomic number of an element is the number of protons in the neucleus.
This is what defines the element.eg, If there are 6 protons then the element is carbon. If there are 7 protons then the element is nitrogen.

So the atomic number of Na = 11
It has 11 protons.


The mass number of an element is the number of protons + the number of neutrons.
The mass number of an element can vary, because an element can have different numbers of neutrons. (But always has the same number of protons.
Atoms of elements that have different numbers of neutrons are called isotopes

So the mass number of this Na atom = 11 + 12 = 23


The electrons play no part in determining mass or atomic number.
A neutral atom will have the same number of electrons as there are protons.
A charged atom (ion) will have either more (-ve ion) or less (+ve ion) electrons then there are protons.