The atomic number is consider a unique atom and element identifier. describe the associated subatomic particle, and how it can be used to identify the atom. a) the number of electrons changes in a unique way as the charge on the atom changes. b) the proton number remains constant through changing the atomic charge, energy, and isotopes. c) as the atom absorbs photons the way the photons interact in the nucleus gives the atomic number. d) all isotopes of the an element have the same number of neutrons allowing it to describe the unique atom.