What is a radioactive isotope? Describe two scientific uses of radioactive isotopes.

They are different forms of the same element.

that differ only in the number of neutrons in their nuclei are termed . Example: Hydrogen, Deuterium, and Tritium are isotopes of hydrogen with 0, 1, and 2 neutrons in their nuclei respectively.

U-235 is an isotope of Uranium that is used in nuclear reactors. Deuterium oxide, D2O or 'heavy water' is also used for nuclear reactions. It's also used as a in the analysis of organic substances. Isotopes of Iodine and Cobalt are used to treat certain cancers.