Flerovium

The 'island of stability' is a hypothetical region where some superheavy nuclei could last longer than others. Models predict that certain proton and neutron combinations would provide additional stability. Flerovium is studied in this context, but it has not yet been demonstrated that an island with durable elements in the everyday sense exists. Investigating new isotopes helps verify these predictions.

Calcium-48 is a miraculous natural isotope for nuclear physics: it has twenty protons and twenty-eight neutrons, being doubly magic. This quantum symmetry confers it exceptional rigidity and a large neutron excess without being radioactive. When fired against actinide targets such as plutonium-244, calcium-48 contributes the indispensable neutrons to reach the superheavy element region without being destroyed by premature fission in the collision.

In experiments at Dubna's cyclotron, individual flerovium atoms were transported by helium gas over a matrix of gold-coated silicon detectors subjected to a cryogenic temperature gradient. Flerovium did not adhere at room temperature like lead, but traveled to detectors at −90 °C before weakly adsorbing. This experimentally confirmed that flerovium is an extraordinarily volatile element compared to lead.

Advanced computational chemistry theoretical calculations with Dirac-Fock relativistic equations indicate that the energy required to unscreen the two electrons of the 7p₁/₂ orbital and promote them to the 7p₃/₂ level is insurmountable for ordinary chemical oxidants. Therefore, molecules such as flerovium tetrafluoride (FlF₄) would be thermodynamically unstable and would spontaneously decompose into difluoride and gaseous fluorine, confirming that traditional tetravalent carbon chemistry does not govern flerovium.

Flerovium is below lead in group 14, but its atoms are much heavier. Relativistic effects can alter the energy of its outer electrons and make them participate less in some reactions. Therefore, calculations predict flerovium could be less reactive and more volatile than lead. However, only a few atoms have been studied and many of its properties remain uncertain.

In heavy atoms, relativistic coupling between the electron's magnetic spin and its orbital motion energetically separates p orbitals into two subshells with angular momentum j=1/2 and j=3/2. In flerovium, the energy gap between 7p₁/₂ and 7p₃/₂ exceeds three electronvolts. As a consequence, promoting electrons to form tetravalent (+4) compounds such as lead tetrachloride is energetically unviable, limiting its chemistry to divalent or neutral bonds.

Georgy Flyorov was one of the most brilliant nuclear physicists of the 20th century. In 1940 he discovered uranium spontaneous fission and in 1942 wrote a famous secret letter to Stalin alerting about the absence of atomic articles in Western journals, boosting the Soviet nuclear program. In 1957 he founded Dubna's Nuclear Reactions Laboratory, undisputed pioneer in transactinide synthesis for over five decades.