Element 115: How chemists discovered the newest member of the periodic table

Element 115: How chemists discovered the newest member of the periodic table

• By AKSHAY PRAKASH

Thanks to the work of chemists at Lund University in Sweden, a brand new element has taken a seat at the periodic table: Element 115, or ununpentium (Uup) as it is currently known. Ununpentium (which is sadly just the Latin/Greek for “115,” not a homage to the Intel CPU) is one of the heaviest elements ever created, extremely rare (it probably only occurs in nature a few milliseconds after a star goes supernova), and realistically won’t impact your life at all. Still, it’s a good chance to discuss how chemists create super-heavy elements — and more importantly, why.

The heaviest (i.e. highest atomic number) readily occurring element in nature is uranium, with 92 protons. Every element above it, including plutonium, americium, and einsteinium, can only be created through processes such as fusion, or being bombarded with neutrons. Fairly large quantities of americium, for example, are produced when uranium and plutonium are bombarded by neutrons in a nuclear reactor. In the lab, most super-heavy elements are created by fusing lighter elements in a particle accelerator. Ununpentium, for example, was created by firing calcium-48 ions (a nucleus with 20 protons and 28 neutrons) at an americium target (with 95 protons and 148 neutrons), creating a fused nucleus of ununpentium-291 with 115 protons and 176 neutrons.

As for why chemists create super-heavy elements, there are a number of reasons. A lot of it is simply down to Russia and the US competing to see who could discover the most exotic elements. Curiosity, of course, also plays a big part — humans love seeing how far they can go, just for the sake of testing the universe’s boundaries. Most importantly, though, there is some science to be gained from such experiments. With each new element that we discover, our knowledge of the periodic table, and thus the universe, swells. The mere fact that we were able to synthesize these heavy elements in the lab means there’s a good chance that they exist elsewhere in the universe — perhaps in the supernova of a dying star, or harnessed by an advanced alien race. (See: 500MW from half a gram of hydrogen: The hunt for fusion power heats up.)

Each new element also teaches us a little bit more about the island of stability — a set of as-yet-undiscovered super-heavy transuranic isotopes that are theorized to have a half-life of days or years, as opposed seconds. (The handful of unstable ununpentium isotopes created by the Swedish researchers decayed in just a few milliseconds). The theory is that, if we can cram in a certain “magic number” of protons and neutrons, these elements will suddenly become very stable. As it stands, though, we lack the technology to squeeze enough neutrons into the synthesized nucleus — and a nucleus with the wrong number of neutrons is very unstable. If we ever reach the island of stability, these stable super-heavy elements might be very useful for energy storage.

Ununpentium was originally created by Russian scientists in 2004. For an element to be officially discovered, though, a second group must replicate the work — which is what the Lund University chemists have done. Now that ununpentium has been confirmed, the IUPAC (International Union of Pure and Applied Chemistry) will meet to discuss an official name for element 115. Usually the name will be derived from something apolitical, such as a famous research or institution that is globally recognized for their work in science. Or, if IUPAC has some gamers on the board, maybe they’ll name it elerium…