Question

An atom of sodium has 11 protons, 11 electrons,and 12 neutrons, what is its atomic number and mass number?

Answer 1

Example: A sodium atom contains 11 protons, so its atomic number is 11. Mass number is the total of the protons and neutrons together, and it is given the symbol A. Example: A sodium atom contains 11 protons and 12 neutrons; its mass number A is 23.