In order to find out how many protons a sodium atom has, you have to look at the periodic table. Sodium is Na on the periodic table and you look for the number on the top of the symbol and you can see that it has 11 protons. To find out how many neutrons, you have to subtract 11 from the mass number, which is 23. 23-11 = 12.
12 neutrons; 11 protons
