Isotopes of an element differ in the number of neutrons in their nuclei. Each atom is characterized by the number of protons found in its nucleus, which defines the atomic number of the element. However, atoms of the same element can have varying numbers of neutrons; these variations are known as isotopes. Despite these differences in neutron numbers, isotopes of an element maintain the same chemical properties, as these are determined by the electron configuration, which in turn is dictated by the number of protons. The differing number of neutrons does, however, affect the atomic mass of the isotopes, resulting in isotopes having different atomic masses while belonging to the same element.