Explain how the isotopes of an element differ

Isotopes of an element will contain the same number of protons and electrons but will differ in the number of neutrons they contain. In other words, isotopes have the same atomic number because they are the same element but have a different atomic mass because they contain a different number of neutrons.

Isotopes of an element have a same atomic number but differ in their atomic masses. Atomic number indicates a number of protons and atomic mass indicate the number of neutrons plus proton present in the atom. So atoms with the same number of protons but different number of neutrons are termed as isotopes.