Isotopes and Radioisotopes

Isotopes are atoms of an element with the same number of protons but a different number of neutrons, which results in forms of the same element with different mass numbers but same atomic number.

For example, elemental hydrogen has three isotopes - hydrogen with zero, deuterium with one, and tritium with two neutrons.

Usually heavier isotopes of certain elements tend to have an unstable nucleus that emits radiation through radioactive decay, transforming them into other stable non-radioactive products. Such isotopes are called radioisotopes.

For instance, tritium, the heavy isotope of hydrogen, undergoes beta decay. One of its two neutrons is transformed into a proton by the emission of a low energy beta particle producing a more stable non-radioactive helium-three isotope.

Weak radioactive isotopes can be traced inside the human body to study bodily functions and assist in disease diagnosis.

For instance, positron emission tomography uses a fluorine-18 tagged fluorodeoxyglucose radiopharmaceutical to identify cancer cells.

Another radioisotope, thallium-201, is used to monitor blood flow to the heart, aiding in the diagnosis of heart diseases.