Back to the basics: What is a rare isotope?

You may have heard the word “isotope”. It sometimes comes up in discussions with a medical doctor, where an isotope can be used for diagnosis or treatment. Other times you might hear it in discussions about archeological findings, where isotopes are used for figuring out how old the findings are. You might also have heard it as part of agriculture discussions, where isotopes are used for tracking fertilizers and pesticides to learn how they affect the plants and the environment.

Although isotopes are commonly used in various aspects of our lives, most people don’t have a good idea of what an isotope is. And on top of that, sometimes we talk about “rare isotopes”, which makes it even more confusing.

So, what is an isotope?

Isotope is a fancy technical term we use to talk about different nuclear species. Every chemical element we know, like oxygen, silver or gold, has lighter and heavier “versions”, called “isotopes.” And while heavy silver and light silver will still look like the shiny metal we all know and love, the different isotopes of silver will have very different nuclear properties. One might only live for a few seconds, while the other can live forever. They might release different amounts of energy, and also different types of radiation, properties that make them useful for different purposes.

Let’s take an element that is easy to draw as a cartoon (figure) and look more closely at the protons and neutrons that make up its isotopes. Beryllium is element number 4. This means that isotopes of beryllium will always have 4 protons. The thing that makes isotopes different is the number of neutrons. In our beryllium example, 5 neutrons + 4 protons will make beryllium-9, which is the stable form of beryllium we find naturally. All other isotopes of beryllium are not naturally occurring, and therefore are called “rare isotopes.” Beryllium-7 will live for a few months; beryllium-11 will live for a few seconds, and beryllium-10 for a few million years.

To study these rare isotopes, and to use them in different applications we have to make them in the lab. Such laboratories are typically called Rare Isotope Facilities. This type of laboratory takes stable, common isotopes and uses them to create rare ones. Rare Isotope laboratories have created about 3000 rare isotopes, to study and to use in various aspects of our lives. Scientists, however, believe that there are about 7000 different isotopes in our Universe, so there is still a lot to learn. More about these rare isotope facilities coming soon!!!

And you might ask: Why should I care about these “rare isotopes”?

Well, many rare isotopes have properties that make them really useful. For example, technicium-99 is one such rare isotope, and is the most frequently used isotope in medical applications. Carbon-14 is well known because it’s frequently used to figure out the age of things. Americium-241 is another common isotope that is used in smoke detectors. More details about useful isotopes in a future post.

So… the next time the term “rare isotopes” comes up, you’ll know exactly what they are and why they are useful.