Isotopes are versions of an element that have different numbers of neutrons but the same number of protons. They have identical chemical properties but different physical properties due to their varying masses.
Related terms
Radioisotopes: Isotopes that are unstable and undergo radioactive decay.
Stable Isotope: An isotope that remains unchanged over time because it does not undergo radioactive decay.
Isotope Abundance: The percentage of a particular isotope in a sample of an element.