What are isotopes?

Isotopes are different forms of an atom that have a different number of neutrons.

Isotopes of the same atom have the same atomic number but a different mass number.

isotopes are named after the atom and the mass number.

They have the same atomic number but different mass numbers. Or the same number of protons, but a different number of neutrons. (They are the same element, same chemical properties, but different melting points and densities)