How do isotopes work

O, then, has the same number of protons and neutrons: eight. Among this trio, O and O are the lighter isotopes, and O is also the most abundant isotope of the three.

Some combinations are stronger than others. Scientists classify O, O and O 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 nucleus in a radioactive isotope, also called a "radioisotope," is unstable and will decay over time. A radioactive isotope has a proton-to-neutron ratio that's fundamentally unsustainable in the long run. Nobody wants to stay in that predicament.

Hence, radioactive isotopes will shed certain subatomic particles and release energy until they've converted themselves into nice, stable isotopes. O is stable, but oxygen O is not.

The latter will inevitably break down — fast! Within That means O has a half-life of A half-life is the amount of time it takes 50 percent of an isotope sample to decay.

Remember this concept; we're going to connect it to paleontology in the next section. But before we talk 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, one of the most well-known radioactive elements. 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 an altogether different element on the periodic table.

Don't bother trying to watch the transition in real time. The process unfolds very, very slowly. Uranium U , the element's most common isotope, has a half-life of about 4. Gradually, this will become lead Pb , which is stable. Likewise, uranium U — with its million-year half-life — transitions into lead Pb , another stable isotope.

Both U and U are examples of naturally occurring isotopes. To geologists, this is really useful information. Let's say somebody finds a slab of rock whose zircon crystals contain a mixture of U and Pb The ratio of these two atoms can help scientists determine the rock's 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 uranium's 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.

Paleontologists harness this strategy to determine how much time has elapsed since a particular fossil was deposited. But you may not realise that each square on the periodic table actually represents a family of isotopes — atoms which share the same name and chemical properties, but have different masses. To understand what isotopes are and how we can use them, we need to take a closer look at the interior of an atom.

An atom is composed of an incredibly dense core called a nucleus of protons and neutrons , surrounded by a diffuse cloud of electrons. You can think of protons and neutrons as the same kind of particle with one key difference: the protons are positively charged, while neutrons carry no charge. The electrons, which are much lighter than protons or neutrons, carry the same magnitude of charge as a proton but with the opposite sign, meaning that each atom that has equal numbers of protons and electrons is electrically neutral.

Isotopes of an element share the same number of protons but have different numbers of neutrons. There are three isotopes of carbon found in nature — carbon, carbon, and carbon All three have six protons, but their neutron numbers - 6, 7, and 8, respectively - all differ.

Chemically, all three are indistinguishable, because the number of electrons in each of these three isotopes is the same. So different isotopes of the same element are identical, chemically speaking.

But some isotopes have the ability to circumvent this rule by transforming into another element entirely. This transformative ability some isotopes have has to do with the fact not all isotopes are stable, and is what led Frederick Soddy to his Nobel Prize-winning discovery of isotopes in Some isotopes - such as carbon - will happily continue to exist as carbon unless something extraordinary happens. Others - carbon, say - will at some point decay into a stable isotope nearby.

In this case, one of the neutrons in carbon changes into a proton, forming nitrogen During this process, which is known as beta decay , the nucleus emits radiation in the form of an electron and an antineutrino. There are many factors that can cause a nucleus to decay. DOE Explains offers straightforward explanations of key words and concepts in fundamental science. Hydrogen and its two naturally occurring isotopes, deuterium and tritium.

Isotope Facts All elements have isotopes. There are two main types of isotopes: stable and unstable radioactive. There are known stable isotopes. All artificial lab-made isotopes are unstable and therefore radioactive; scientists call them radioisotopes. Some elements can only exist in an unstable form for example, uranium. Hydrogen is the only element whose isotopes have unique names: deuterium for hydrogen with one neutron and tritium for hydrogen with two neutrons.