Flerovium

Flerovium, element 114, is positioned directly below lead in Group 14 and carries the predicted electron configuration [Rn] 5f14 6d10 7s2 7p2. It lies at what nuclear physicists call a magic proton number for superheavy nuclei — 114 protons sit close to a predicted closed nuclear shell — making flerovium's isotopes among the longest-lived in the superheavy region. Fl-289 has a half-life of about 2.6 seconds, long enough for gas-phase chemical experiments. Relativistic effects are predicted to stabilize flerovium's 7s and 7p electrons so strongly that it may behave less like lead and more like a noble gas, potentially making it extremely volatile and chemically inert.

Flerovium is studied primarily to probe the nuclear shell model near the predicted island of stability, where certain combinations of proton and neutron numbers are expected to confer anomalous longevity on superheavy nuclei. Gas-phase adsorption experiments at GSI and JINR have attempted to measure flerovium's interaction with gold surfaces, with results suggesting it is unusually volatile. These measurements test the predictive power of relativistic atomic theory and inform the search for even heavier, longer-lived isotopes near the stability island's center.

Flerovium was first synthesized at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, in December 1998 by a team led by Yuri Oganessian. The experiment fused calcium-48 ions with a plutonium-244 target, producing an atom of element 114. The hot fusion technique using calcium-48 beams proved far more productive for reaching superheavy elements than the cold fusion approach used at GSI, and subsequent experiments confirmed several isotopes of flerovium over the following years. IUPAC formally recognized the discovery in 2011 and approved the name flerovium — honoring the Flerov Laboratory of Nuclear Reactions at JINR, itself named for Soviet nuclear physicist Georgy Flyorov, a pioneer of heavy element research — along with the symbol Fl in 2012.

Flerovium does not occur naturally. Its nucleus requires 114 protons and enough neutrons to achieve adequate stability, a configuration that cannot be assembled by any natural process occurring on Earth. Even in neutron star merger ejecta, the r-process nucleosynthesis that builds heavy nuclei proceeds along neutron-rich pathways and would not produce the proton-rich isotopes of flerovium accessible to present accelerator techniques.

No chemical compounds of flerovium have been synthesized. Gas-phase chromatography experiments designed to measure adsorption on gold and silicon oxide surfaces yielded results interpreted as evidence of weak metallic interaction and high volatility, though debate continues about whether the observations indicate noble-gas-like or highly volatile metallic behavior. Theoretical predictions suggest that flerovium's closed-shell-like electronic structure might make it more chemically inert than any other Group 14 element, with even simple fluorides such as FlF2 possibly being only marginally stable.

• Element 114 sits near the theorized island of stability, where nuclear shell closures are predicted to give superheavy nuclei lifetimes far longer than their neighbors — Fl-289 with its 2.6-second half-life is already considered long-lived by superheavy element standards.
• Gas-phase experiments studying flerovium atoms bouncing along a gold-coated detector found that the element barely stuck at all, suggesting it may be more volatile than even mercury, its nearest metallic neighbor in volatility.
• The Flerov Laboratory of Nuclear Reactions, for which flerovium is named, was founded by Georgy Flyorov, who also wrote a letter to Joseph Stalin in 1942 arguing that the West's silence on nuclear fission research was ominous — a letter that helped spur the Soviet atomic bomb program.
• Calcium-48, the beam used to make flerovium, is itself an extraordinarily rare isotope comprising only about 0.187 percent of natural calcium; accelerator experiments require careful enrichment and recycling of this precious material.
• Flerovium is predicted by some relativistic calculations to have a filled-shell electronic character akin to a noble gas, which would make Group 14 — normally home to carbon, silicon, and lead — harbor one of the least reactive elements in the entire periodic table.