Isotopes of an element have the same chemical properties because they have the same number of protons and electrons. The chemical behavior of an atom is primarily determined by its electron configuration, especially the electrons in the outer shell that participate in chemical reactions. Since isotopes have the same atomic number (number of protons) and thus the same number of electrons arranged in the same manner, their chemical properties are identical. The difference in the number of neutrons among isotopes affects only their physical properties, such as mass, density, and stability, but does not influence the way they chemically react with other atoms. Neutrons have no charge and do not impact the electron arrangement that governs chemical behavior. As a result, isotopes like carbon-12 and carbon-14 exhibit the same chemical reactivity even though they differ in mass.