Why do isotopes of an element have similar chemical properties?

Isotopes of an element exhibit nearly identical chemical properties because they possess the same atomic number—meaning they have the same number of protons in their nucleus—and, consequently, the same number of electrons.12

In chemistry, the chemical behavior of an atom is determined by the number and arrangement of its electrons, particularly those in the outermost valence shell. Because isotopes of the same element have the same electronic configuration, they interact with other atoms in the same way during chemical reactions. While isotopes differ in their number of neutrons and their atomic mass, these differences primarily affect physical properties rather than chemical reactivity.321