the atomic number of an element is the total number of which particles in the nucleus? (1 point) neutrons protons electrons protons and electrons 4. all atoms of the same element have the same _____. (1 point) a. number of neutrons b. number of protons c. mass numbers d. mass 5. isotopes of the same element have different _____. (1 point) a. positions on the periodic table b.chemical behavior c. atomic numbers d. mass numbers