Welcome to brain Stuff production of I Heart Radio. Hey, brain Stuff, Laurin bobble bomb. Here. Atoms are the building blocks of matter. Anything that has mass and occupies space by having volume is made up of these we things that goes for the air you breathe, the water you drink, and your body itself. Isotopes are a vital concept in the study of atoms and how they work. Chemists, physicists, and geologists use them to make sense of our world.
But before we can explain what isotopes are or why they're so important, we'll need to take a step back and look at atoms as a whole. As you probably know, atoms have three main components, two of which reside in the atoms nucleus, located at the center of the atom. The nucleus is a tightly packed cluster of particles. Some of those particles are protons, which have positive electrical charges. It's well documented that opposite charges attract, while similarly charged
bodies tend to repel one another. I think about the ends of two magnets. So here's a question. How can two or more protons with their positive charges come exist in the same nucleus? Shouldn't they be pushing each other away. That's where another type of particle comes in, neutrons. Neutrons are subatomic particles that share nuclei with protons, but neutrons don't possess an electrical charge. True to their name, neutrons are neutral, being neither positively nor negatively charged. It's an
important attribute. By virtue of their neutrality, neutrons can stop protons from driving one another clear out of the nucleus. Orbiting the nucleus are the third main component of atoms, electrons, which are ultra light particles with negative charges. Electrons facilitate chemical bonding, and their movements can produce a little thing called electricity. But protons are no less important for one thing,
they help scientists tell the elements apart. You might have noticed that in most versions of the periodic table, each square has a little number printed in its upper right hand corner. That figure is known as the atomic number. It tells the reader how many protons are in the atomic nucleus of a given element. For example, Oxygen's atomic number is eight. Every oxygen atom in the universe has a nucleus with exactly eight protons, no more, no less.
Without this very specific arrangement of particles, oxygen wouldn't be oxygen. Each elements atomic number, including oxygen's, is totally unique, and it's a defining trait. No other element has eight protons per nucleus. By counting the protons, you can identify an atom. Just as oxygen atoms will always have eight protons, nitrogen
atoms invariably come with seven. It's that simple neutrons do not follow suit the nucleus, and an oxygen atom is guaranteed to harbor eight protons as we've established, However, it might also contain anywhere from four to twenty neutrons. Isotopes are variants of the same chemical element that have different numbers of neutrons. Now, each isotope is named on the basis its mass number, which is the total combined number
of neutrons and protons in an atom. For example, one of the better known oxygen isotopes is called oxygen eighteen because it's got the standard eight protons plus ten neutrons. A related isotope, oxygen seventeen, has one fewer neutron in the nucleus. Some combinations of subatomic particles are stronger than others.
Scientists classify oxygen seventeen and eighteen as stable isotopes. In a stable isotope, the forces exerted by the protons and neutrons hold each other together permanently, keeping the nucleus intact on the flip side. The nuclei in radioactive isotopes, also called radio isotopes, are unstable and will decay over time. These things have a protons neutron ratio that's fundamentally unsustainable
in the long run. Nobody wants to stay in that predicament. Hence, radioactive isotopes will shed some subatomic particles and release energy while they're at it until they've converted themselves into nice stable isotopes. So oxygen eighteen is stable, but oxygen nineteen is not. The latter will inevitably break down and fast within twenty six point eight eight seconds of its creation. Any given sample of oxygen nineteen is guaranteed to lose
half of its atoms to the ravages of decay. That means of oxygen nineteen has a half life of twenty six point eight eight seconds. A half life is the amount of time it takes of an isotope sample to decay. Remember this concept, we're going to connect it to paleontology in just a minute. But before we talk about fossil science, there's an important point that needs to be made. Unlike oxygen, some elements do not have any stable isotopes whatsoever. Consider
uranium in the natural world. There are three isotopes of this heavy metal, and they're all radioactive. With the atomic nuclei in a constant state of decay. Eventually a chunk of uranium will turn into it altogether different element. Don't bother trying to watch the transition in real time, though the process unfolds very very slowly. Uranium two thirty eight, the elements most common isotope, has a half life of about four point five billion years. Gradually it will become
lead to OH six, which is stable. Likewise, uranium two thirty five, with its seven hundred and four million year half life, transitions into lead to OH seven, another stable isotope. Two geologists, this is really useful information. Let's say somebody finds a slab of rock whose zircon crystals contain a mixture of uranium two thirty five and lead to OH seven. The ratio of those two atoms can help scientists determine the rocks age. Here's how Let's say the lead atoms
vastly outnumber their uranium counterparts. In that case, you know you're looking at a pretty old rock. After all, the uraniums had plenty of time to start transforming itself into lead. On the other hand, if the opposite is true, and the uranium atoms are more common, then the rock must be on the younger side. The technique we've just described is called radiometric dating. That's the act of using the well documented decay rates of unstable isotopes to estimate the
age of rock samples and geologic formations. A Paleontologists have harnessed the strategy to determine how much time has elapsed since a particular fossil was deposited, though it's not always possible to date the specimen directly. You don't need to be a prehistory buff to appreciate isotopes. Medical practitioners use some of the radioactive varieties to monitor blood flow, study bone growth, and even fight cancer. Radio Isotopes have also
been used to give farmers insights into soil quality. So there you have it. Something as seemingly abstract as the variability of neutrons affects everything from cancer treatment to the mysteries of deep time. Science is awesome. Today's episode was written by Mark Mancini and produced by Tyler Clang. Brain Stuff is a production of iHeart Radio's How Stuff Works. For more on this and lots of other stable topics,
visit our home planet has Stuff Works dot com. And for more podcasts on my heart radio, visit the eye heart Rate app, Apple Podcasts, or wherever you listen to your favorite shows. H