An isotope is a variant of an element that has the same number of protons, but a different number of neutrons in the nucleus, resulting in a different atomic mass. Isotopes of an element have similar chemical properties, but may have different physical properties such as radioactivity. Some isotopes are stable, while others are unstable and undergo radioactive decay over time. Isotopes can be used in a variety of applications, including medical diagnostics, nuclear energy, and dating materials in geology or archaeology.
