Home ยป Atoms that have the same mass number and different atomic number are called? Atomic Structure MCQs Atoms that have the same mass number and different atomic number are called? January 8, 2022 15 Views Q. Atoms that have the same mass number and different atomic number are called? A. Isotopes. B. Isotones. C. Isobars. D. Isomers. Answer: Isotopes.