Isotopes are variants of a chemical element that possess the same number of protons but differ in their number of neutrons. Because the number of neutrons varies, isotopes exhibit different atomic masses and, consequently, different physical and chemical properties. Certain isotopes are stable and decay slowly, while others are radioactive and undergo measurable decay over time, releasing energy. This property allows for various scientific applications, including radiometric dating of geological formations, and in the fields of medicine and industry, specific isotopic materials are utilized for diagnostic imaging, treatment, and tracer studies due to their predictable decay chains and characteristic radiation signatures.