The search for new elements on the periodic table started with a blast

January 7, 2016 by James Tickner, Csiro, The Conversation
New elements were discovered in early thermonuclear bomb tests. Credit: Pixabay

So the periodic table has expanded again with the addition late last year of four new superheavy elements, bringing the known total up to 118.

But the hunt for new elements started with efforts to develop nuclear power and the atomic bomb during World War II. At the time, uranium was the heaviest known element, sitting at number 92 in the .

Researchers quickly discovered that when uranium is placed in a nuclear reactor, a complex sequence of interactions leads to the production of several so-called transuranic elements (elements beyond uranium).

Probing around in the debris of the first hydrogen bomb test revealed two further transuranic elements, einsteinium and fermium, bringing the total to an even 100.

Some of these elements are more commonly encountered that you might think. Most families would own some americium (element number 95) in the form of an every-day smoke detector, and californium (number 98) is widely used in industrial analysers. At a cool US$60 million dollars per gram, however, californium is about a million times more expensive than gold.

Beyond the century element

Beyond element 100, not even a hydrogen bomb is powerful enough to make progress, and scientists had to change tack in their quest for ever heavier elements. They substituted finesse for brute force, using particle accelerators to fire atoms onto carefully chosen targets.

Under the right conditions, the nuclei of atoms in the beam and target can fuse together and produce new elements. Fittingly, the first element made in this way, mendelevium, was named after Dimitri Mendeleev, the creator of the periodic table.

Russian and American scientists continued to push forward through the 1950s, 60s and 70s, eventually reaching element 106. Reflecting the tensions of the Cold War years, priority for discovering these elements was strongly contested, with claims and counterclaims over ambiguous experimental results.

Not until 1997 did the International Union of Pure and Applied Chemistry (IUPAC) credit the discoverers of these elements and announce official names, mostly based on US and Soviet scientists and cities.

The Germans picked up the baton in the 1980s and 90s, discovering elements 107 through to 112.

German researchers added a strongly European flavour to the naming scheme, honouring the physicists Niels Bohr (bohrium), Lise Meitner (meitnerium), and Wilhelm Röntgen (roentgenium), the astronomer Nicolaus Copernicus (copernicium) and their home city and state – darmstadtium and Hassium are named after the town of Darmstadt and the German state of Hesse (passing through Latin along the way, which changes the 'e' to an 'a'. Nothing's ever simple!).

Only a handful of atoms of these elements have ever been produced.

Let's get super-heavy

Moving on to still , the hunt becomes increasingly difficult for three reasons.

First, the probability of two nuclei successfully fusing to form a new element rapidly decreases. Second, these super-heavy elements are extremely unstable, so any atoms produced have a fleeting existence. And third, it becomes increasingly difficult to untangle the complex signatures that reveal their momentary creation and decay.

Reflecting improved international relations in the post-Glasnost era, most of the recent discoveries have been credited to collaborations between US and Russian researchers. Elements 114 (flerovium) and 116 (livermorium) were announced by the IUPAC in 2012.

The most recent announcement awards discovery of elements 115, 117 and 118 to the same groups. A Japanese team, working independently, has been recognised for element 113.

Producing even a sniff of these super-heavy elements is a heroic endeavour. To discover element 118, for example, experimenters fired a beam of calcium atoms for months at a time onto a target loaded with the element californium.

The odds of any one calcium atom fusing is tiny, roughly the same as winning the Oz Lotto jackpot, but then being killed by a lightning strike 15 minutes later.

The work resulted in just three atoms of the new element, each of which lasted for about 1000th of a second. Registering these atoms is just as difficult: a sophisticated detector system is need to pick up the cascade of radioactive decays which end with the atomic nucleus blowing itself apart.

Why the search for new elements?

All of which begs the question: why bother? After all, it's hard to come up with a practical use for an element that takes so much effort to produce and lasts for so short a time.

Studying these super-heavy elements can teach us not only about the forces involved in atomic nuclei, but perhaps surprisingly, also about what goes on when stars die.

When a massive star explodes as a supernova, the extreme conditions could be just right for producing super-heavy elements. There are theoretical hints that some of these elements may buck the trend of increasing instability and exist in long-lived forms, an effect known as "the island of stability".

Current earth-bound experiments are just probing the shores of this island, but will help us determine whether these super-heavy elements could already be present in the universe. Searches in terrestrial rocks and in debris from space have so far drawn a blank, but researchers continue to hunt.

The four new additions to the periodic table have only temporary names at the moment. Rights for naming them go to the discoverers, although the IUPAC imposes strict rules.

Japonium has been suggested as a candidate for element 113, which would make it the first starting with J. Now if scientists can just come up with a good name starting with Q, the periodic table would be alphabetically complete.

Explore further: The race to find even more new elements to add to the periodic table

Related Stories

Lab scientists discover five new nuclei

October 28, 2015

Lawrence Livermore scientists, in conjunction with international researchers, have discovered five new atomic nuclei to be added the chart of nuclides.

A new chemical element in the periodic table

June 10, 2009

The element 112, discovered at the Centre for Heavy Ion Research (GSI Helmholtzzentrum für Schwerionenforschung) in Darmstadt, has been officially recognized as a new element by the International Union of Pure and Applied ...

Recommended for you

Researchers turn light upside down

February 23, 2018

Researchers from CIC nanoGUNE (San Sebastian, Spain) and collaborators have reported in Science the development of a so-called hyperbolic metasurface on which light propagates with completely reshaped wafefronts. This scientific ...

Recurrences in an isolated quantum many-body system

February 23, 2018

It is one of the most astonishing results of physics—when a complex system is left alone, it will return to its initial state with almost perfect precision. Gas particles, for example, chaotically swirling around in a container, ...

Hauling antiprotons around in a van

February 22, 2018

A team of researchers working on the antiProton Unstable Matter Annihilation (PUMA) project near CERN's particle laboratory, according to a report in Nature, plans to capture a billion antiprotons, put them in a shipping ...

Urban heat island effects depend on a city's layout

February 22, 2018

The arrangement of a city's streets and buildings plays a crucial role in the local urban heat island effect, which causes cities to be hotter than their surroundings, researchers have found. The new finding could provide ...

New quantum memory stores information for hours

February 22, 2018

Storing information in a quantum memory system is a difficult challenge, as the data is usually quickly lost. At TU Wien, ultra-long storage times have now been achieved using tiny diamonds.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.