Question

If two are atoms are isotopes of the same elements the atoms must have

Answer 1

The atoms must have the same number of protons.

Isotopes mean that there are atoms with the same number of protons, but a different number of neutrons.

For example, carbon 12 and carbon 14 are isotopes. Both have 6 protons, but carbon 12 has 6 neutrons, whereas carbon 14 has 8.

Answer 2

Each atom has a few isotopes, which are atoms with the same amount of protons, but more or less neutrons. This doesn't affect the atom greatly, because neutrons have no charge. The main differneve between isotopes is the weight. Neutrons have the most mass out of protons, electrons, and neutrons, so isotopes with more neutrons would be heavier.

If two atoms are isotopes of the same element, the atoms must have the same amount of protons.