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Elizabeth Williams receives capital from the Australian research study Council.

You are watching: What properties of radioactive isotopes make them useful

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The routine table of elements. Cepheus/Wikimedia

Building block of matter

An atom is written of an incredibly thick core (called a nucleus) of protons and also neutrons, surrounded by a diffusive cloud of electrons.


You have the right to think of protons and neutrons together the exact same kind of bit with one an essential difference: the protons space positively charged, when neutrons lug no charge. This means protons deserve to “feel” electrical or magnetic fields, while neutrons cannot.

The electrons, i beg your pardon are lot lighter 보다 protons or neutrons, lug the exact same magnitude of fee as a proton yet with the contrary sign, definition that each atom that has equal numbers of protons and also electrons is electrically neutral.

It is the electrons that recognize the chemical behaviour the a particular element.


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The Map that Nuclides contains information around all known isotopes. The limits of this map space constantly spreading, as new research help us find ways come make new isotopes. Aspects are assigned a heat on the chart according to the number of protons lock have. Steady isotopes are displayed in black. National Nuclear Data facility / Wikimedia Commons

Isotopes the an facet share the same variety of protons however have different numbers of neutrons. Let’s usage carbon together an example.

There space three isotopes of carbon found in nature – carbon-12, carbon-13, and also carbon-14. All three have six protons, but their neutron numbers - 6, 7, and also 8, respectively - every differ. This way that all three isotopes have various atomic masses (carbon-14 being the heaviest), yet share the exact same atomic number (Z=6).

Chemically, all three room indistinguishable, since the number of electrons in every of these 3 isotopes is the same.

So different isotopes of the same aspect are identical, chemically speaking. However some isotopes have the ability to circumvent this preeminence by transforming into one more element entirely.


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3 naturally arising carbon isotopes. When each have the same variety of protons and also electrons, they differ in the variety of neutrons. Tessa Koumoundouros

Marching in the direction of stability

This transformative capability some isotopes have has to do through the fact not every isotopes space stable, and is what led Frederick Soddy to his Nobel Prize-winning exploration of isotopes in 1913.

Some isotope - such as carbon-12 - will happily continue to exist together carbon uneven something particularly happens. Others - carbon-14, to speak - will at some suggest decay into a stable isotope nearby.

In this case, one of the neutron in carbon-14 changes into a proton, creating nitrogen-14. During this process, i beg your pardon is recognized as beta decay, the cell core emits radiation in the type of one electron and an antineutrino.


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A carbon-14 ghost turns right into a proton during beta decay. Tessa Koumoundouros

There are many factors the can cause a nucleus come decay. Among the most crucial is the proportion of proton to neutrons a specific nucleus has. If a nucleus has actually too numerous neutrons (the meaning of “too many” depends on how heavy the cell nucleus is), over there is a opportunity that that will decay towards stability.

The very same is true if a nucleus has actually too numerous protons. This is among the factors why part isotopes that a given element are radioactive, if others space not.

From the bellies that stars

By now, you may be wondering exactly how all these isotopes were created in the very first place. As it turns out, this inquiry is a complex one, yet lends some reality to the adage the we are all make of star dust.

Some that the lighter isotope were formed an extremely early in the history of the universe, during the big Bang. Others an outcome from processes that occur within stars or together a an outcome of opportunity collisions between highly energetic nuclei - recognized as cosmic beam - in ~ our atmosphere.

Most normally existing isotopes space the last (stable or long-lived) product result from a long collection of atom reactions and also decays.

In many of these cases, irradiate nuclei have had to smash in addition to enough energy to enable the solid force - a glue-like shortcut that creates when protons and neutrons obtain close enough to touch - to get over the electromagnetic force – i beg your pardon pushes protons apart. If the solid force wins out, the colliding nuclei tie together, or fuse, to type a heavier nucleus.

Our sunlight is a great example of this. One of its main sources of strength is a collection of blend reactions and also beta decay processes the transform hydrogen into helium.


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Isotopes decay towards what is sometimes referred to as the “valley the stability.” Araghu/Wikimedia

Transforming knowledge right into tools

Since the early on 1900s, when the presence of isotopes was an initial realised, nuclear physicists and chemists have actually been search out means to study just how isotopes deserve to be formed, how they decay, and how we can use them.

As it turns out, the nature of isotope – their chemical uniformity, your nuclear distinctiveness – provides them helpful for a wide variety of applications in areas as varied as medicine, archaeology, agriculture, power generation and mining.

If friend have ever had a pet scan, you have benefited indigenous a byproduct the the radioactive degeneration of details isotopes (often called medical isotopes). We create these clinical isotopes utilizing our expertise of how nuclear reaction proceed, v the help of atom reactors or accelerators called cyclotrons.

But we have additionally found methods to exploit naturally arising radioactive isotopes. Carbon dating, because that example, makes use that the long-lived isotope carbon-14 come determine just how old objects are.

Under normal circumstances, carbon-14 is developed in our setting via cosmic ray reactions with nitrogen-14. It has a half-life of around 5,700 years, which method that fifty percent of a quantity of carbon-14 will have decayed far in the time period.


inside the Australian nationwide University’s 15 Million Volt accelerator. ANU

While a organic organism is alive, the takes in roughly one carbon-14 isotope because that every trillion steady carbon-12 isotopes and also the carbon-12 come carbon-14 ratio stays about the very same while the biology lives. As soon as it dies, brand-new intake that carbon stops.

This means the ratio of carbon-14 to carbon-12 alters in the remains of this organism end time.

If us extract carbon utilizing chemical approaches from a sample, we deserve to then apply a method called accelerator mass spectrometry (AMS) to different out the individual carbon isotope by weight.

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AMS renders use that the fact that accelerated particles with the exact same charge yet different masses monitor separate courses through magnetic fields. By making usage of these separate paths, we can determine isotope ratios with incredible accuracy.

As you can see from this examples, we use our understanding of isotopes in a variety of ways. We develop them, finding them, extract them, and study them v the double purpose of understanding why the atom nucleus behaves together it does, and also how we can harness its strength for our benefit.