If two atoms have the same mass numbers but different atomic numbers, then they can be considered atoms of the same element. True or False?
False. If two atoms have different atomic numbers, then they cannot be of the same element. The atomic number describes the amount of protons of an atom, which distinguishes the type of element an atom belongs to.
What about isotopes of the same element? They have the same number of electrons and protons but a different amount of neutrons.
Electrons aren't included in the mass number.
That's true I'm just making a point that nothing has changed but the neutron. Also electron's do contribute weight it's just a very tiny number that can be left out.