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Ununennium

physical science Maturity 11-13 Next article →

Ununennium is a hypothetical chemical element that has not yet been discovered. It is also referred to as element 119 or eka-francium. Scientists use the temporary name ununennium and the symbol Uue until a permanent name is chosen. This element would be the first element in the eighth period of the periodic table.

It is currently the lightest element that has not been synthesized in a laboratory. If discovered, it would help scientists understand the very edges of the periodic table.

To create a superheavy element, scientists use a process called synthesis. This involves bombarding a target material with a beam of ions using a particle accelerator. In one method, a projectile nucleus hits a target nucleus to create a new, heavier compound nucleus. This process is extremely difficult because the chance of a successful collision is very low. This low probability is known as a small cross section. The resulting atoms are often highly unstable and exist for only a very short time.

Curium oxide targets
Curium oxide targets

There are different strategies for attempting to synthesize ununennium. One method involves using a berkelium-249 target and a titanium-50 beam. This reaction was predicted to be a favorable way to form the element. However, berkelium-249 decays into californium-249 with a half-life of only 327 days. Another method used by the RIKEN team in Japan involves bombarding curium-248 targets with a vanadium-51 beam. They chose curium because heavier targets like berkelium or californium are harder to prepare.

Curium oxide targets
Curium oxide targets

Research into element 119 has spanned several decades and many locations. In 1985, an attempt was made at the superHILAC accelerator in Berkeley, California, but it failed. Between April and September 2012, researchers at the GSI Helmholtz Centre in Germany tried using berkelium and titanium. They used new, fast electronics to detect decay events that happen within microseconds. Since January 2018, the RIKEN team in Japan has been running experiments 24/7. The Joint Institute for Nuclear Research in Russia plans to begin its own attempts in 2026.

Island of Stability derived from Zagrebaev
Island of Stability derived from Zagrebaev

Ununennium is expected to be an alkali metal located in the s-block. This means it would sit below francium in the periodic table. It would have a valence electron configuration of 8s1, meaning it has one electron in its outermost shell. Most alkali metals are very reactive and typically show a +1 oxidation state. However, ununennium might be different due to relativistic effects. These effects occur because electrons in superheavy atoms move at speeds close to the speed of light.

Next proton shell
Next proton shell

These relativistic effects, specifically the spin-orbit interaction, may change how the element behaves. The spin-orbit interaction is the mutual interaction between an electron's motion and its spin. This interaction can cause subshell splitting, which changes the energy levels of the electrons. Because of this, ununennium might be less reactive than caesium or francium. It might actually behave more like potassium or rubidium. It is also predicted to show +3 and +5 oxidation states, which is unknown in other alkali metals.

Next proton shell
Next proton shell

Stability is a major concern for researchers studying these heavy nuclei. Most isotopes with atomic numbers above 101 have half-lives of less than 30 hours. Ununennium isotopes are expected to be even shorter, with half-lives on the order of microseconds. For example, the isotope 294Uue is predicted to have an alpha-decay half-life of about 485 microseconds. Scientists hope to find stability in a region called the "island of stability." This concept suggests that certain superheavy elements might last longer than others.

Island of Stability derived from Zagrebaev
Island of Stability derived from Zagrebaev

Finding ununennium would connect many different fields of science. It tests our understanding of nuclear physics and the limits of the periodic table. The search for this element pushes the boundaries of modern technology, such as high-intensity beams and fast electronics. It also requires intense international cooperation between laboratories in Japan, Russia, China, and Germany. Success would confirm our theoretical models of how matter is organized at the most extreme levels.

Island of Stability derived from Zagrebaev
Island of Stability derived from Zagrebaev
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🖼️ Images & Media (6)
File:Curium oxide targets.jpg
Curium oxide targets.jpg
File:Island of Stability derived from Zagrebaev.svg
Island of Stability derived from Zagrebaev.svg
File:Next proton shell.svg
Next proton shell.svg
File:Atomic radius of alkali metals and alkaline earth metals.svg
Atomic radius of alkali metals and...
File:Electron affinity of alkali metals.svg
Electron affinity of alkali metals.svg
File:Ionization energy of alkali metals and alkaline earth metals.svg
Ionization energy of alkali metals and...
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