The atomic number of a sodium atom is 11 and its mass number is 23. Take the element, find its atomic number; that is the amount of protons. On the periodic table each element has two numbers. The number of protons and neutrons in the nucleus remain the same as a normal sodium atom, but there is one less electron, altogether 10 electrons. One of which is its mass number the other is the number of protons. He = 2 proton. Question. electrons are considered = 0 amu (very light compared to protons & neutrons) Atomic Number of sodium = 11 ===> 11 protons and 11 electrons. The ion (Na+) has one less electron so means it carries a positive charge of +1. protons and neutrons = 1 amu. Generally the number towards the bottom of the atom is the proton number (atomic number). It will float on water. Its commonest oxidation state is +1 (meaning that it 'donates' a single electron). now it has 10 electrons instead of 11 or say as it has lost 1 -ve, so it gains 1 +ve charge. Take the mass (if it is already given, use that) And subtract the atomic number (proton amount) from it, that is how many neutrons you have. Soduim 22 = 22 amu ===> 22 - 11 = 11 neutrons Number of neutrons in sodium nucleus is 12. Sodium-22 means the mass number (number of protons + neutrons) = 22. It is abundant in the sun and other stars. (keep in mind a neutral specie has equal no. of electrons & protons, while neutrons=at.mass - no. In its neutral state it has 11 protons and 12 neutrons, hence 11 electrons. A negative ION has more electrons than protons, a positive ION has less electrons that protons. e.g: H = 1 proton. It will ignite spontaneously on water. Calculate the number of protons, neutrons and electrons it contains. For any element number of neutrons = mass number - atomic number = 23 - 11 = 12. of electrons or protons, e.g. it's simple.A neutral Na atom has, u know, 11 electrons & 11 protons, 12 neutrons.When there is Na ion, it means it loosed only 1 electron, i.e. the proton number works in order. Sodium chloride or salt (NaCl) Soda ash (Na 2 CO 3) Baking soda (NaHCO 3) Sodium hydroxide or caustic soda (NaOH) Sodium nitrate or Chilean saltpeter (NaNO 3) Sodium Borate or borax (Na 2 B 4 O 7) Interesting facts: It is found free in nature. 23Na is the stable isotope of sodium.