Sodium's atomic number is 11. what does this tell you about an atom of sodium? a. it contains 11 neutrons. b. it contains 11 protons. c. it has 11 protons to lose in ionic bonds. d. its atomic mass is double this amount

The right answer is B: It has 11 protons.

The number of protons contained in a nucleus (which is the atomic number) is characteristic of a chemical element. For a given atomic number, the number of neutrons defines different "types" of this element: isotopes. The variation of the number of protons of the nucleus of an atom, during a nuclear reaction, for example, causes a change in the element studied.

not sure if this what   you'r looking for would be percent composition