Using Radioisotopes in the Sciences

Instructor: David Wood

David has taught Honors Physics, AP Physics, IB Physics and general science courses. He has a Masters in Education, and a Bachelors in Physics.

How are radioisotopes used in science? Learn about their applications for the dating of rocks, in medicine, environmental science and materials science. See what you know with a quiz.

What Are Radioisotopes?

When someone uses the word 'radioactive', what do you think? Maybe you think of nuclear bombs, or power plants, or a radioactive superhero like the Hulk. But radioactive substances are useful in almost every field of science in ways most people don't think about.

A radioisotope is a substance made of unstable, radioactive atoms. These are atoms that have unbalanced forces inside of them and could break apart at any moment, due to having too many neutrons compared to protons, or not enough. When they do that, they turn into other elements, and keep breaking down until they reach a stable state.

In this lesson, we're going to talk about some of the practical uses of radioisotopes in the sciences.

Radiometric Dating

The most well-known example of a use of radioisotopes in science is radiometric dating. Radiometric dating is where the age of materials like rocks (including fossils) can be figured out using our understanding of radioactivity. Radioactive materials decay into other materials over time in a way that is predictable. By looking at the amounts of radioactive elements present in a sample of rock, we can figure out how old that rock is.

Fossils can be dated using radioisotopes
Fossils can be dated using radioisotopes

This can be useful for figuring out the ages of parts of the earth itself, for dating fossils (and see what life was present at different times in Earth's history), and for dating archaeological finds.

Medical Science

Radioisotopes are used in many ways in the medical sciences. They're used to both diagnose and treat diseases. In terms of diagnosis, radioisotopes are used as tracers. Tracers are radioisotopes that are either injected or swallowed by humans. Once inside the body, the radiation they produce can be detected and this can be used to take images of the inside of the body. Tracers can be swallowed to give us a picture of the digestive system or injected to create a picture of the circulatory system.

Image from a radioactive tracer
Image from a radioactive tracer

Radioisotopes are also used in medical treatment. For example, cancers can be bombarded with radiation produced by radioisotopes to kill the cancer cells. Radioisotopes can also be used to sterilize medical instruments. They're even used in drug research, helping us discover new treatments for all kinds of diseases.

Environment and Earth Sciences

Another part of science where radioisotopes are used is environmental and earth science. Radioisotopes can be used to study and detect water resources and detect the presence of pollution. They can also be used in soil and water exposure studies. In these fields, harmless radioactive tracers are used to see how water moves through an area and how easy it is for pollution to move from one area to another.

Materials Science & Construction

Last of all, radioisotopes are used in materials science. When constructing roads, bridges, and buildings, the quality and thicknesses of materials are important factors. If you build a road too thin or with materials that aren't dense enough, it won't do its job properly and might collapse or wear out too soon.

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