Livermorium

Livermorium is a synthetic element with the symbol Lv and atomic number 116. It is highly radioactive and exists only in laboratory settings, with no natural occurrence; as of 2020, roughly 35 atoms had been produced. Its name honors the Lawrence Livermore National Laboratory in California, which worked with Russia’s Joint Institute for Nuclear Research (JINR) in Dubna to discover the element through experiments from 2000 to 2006. The lab itself takes its name from Livermore, California, which was named after rancher Robert Livermore. The International Union of Pure and Applied Chemistry (IUPAC) officially added livermorium to the periodic table on June 1, 2011, and approved its name on May 30, 2012. Six isotopes are known, with mass numbers from 288 to 293; the most stable is livermorium-293, which has a half-life of about 80 milliseconds. A seventh possible isotope, with mass number 294, has been reported but not yet confirmed.

In the periodic table, livermorium sits in the p-block as a transactinide element. It belongs to period 7 and group 16, making it the heaviest chalcogen, though it has not been confirmed to behave like its lighter relative polonium. Calculations suggest it shares some traits with oxygen, sulfur, selenium, tellurium, and polonium, and it is expected to be a post-transition metal, but it should also show several significant differences from them.

The first search for element 116 occurred in 1977, when Ken Hulet’s team at Lawrence Livermore National Laboratory tried to produce it by bombarding curium-248 with calcium-48, but found no atoms. Yuri Oganessian’s group at JINR’s Flerov Laboratory of Nuclear Reactions attempted the same reaction in 1978, also without success. In 1985, a joint experiment between Berkeley and Peter Armbruster’s team at GSI in Germany again yielded nothing, setting a cross-section limit of 10–100 picobarns. Despite these failures, work with calcium-48 beams continued at Dubna. Researchers developed a superheavy element separator in 1989, began searching for target materials and collaborating with LLNL in 1990, produced more intense calcium-48 beams in 1996, and ran long-term experiments with three orders of magnitude higher sensitivity in the early 1990s. This effort directly led to the creation of new isotopes of elements 112 through 118, and the discovery of the five heaviest elements: flerovium, moscovium, livermorium, tennessine, and oganesson.

In 1995, an international team led by Sigurd Hofmann at GSI in Darmstadt, Germany, tried to synthesize element 116 via a radiative capture reaction—where the compound nucleus releases energy purely through gamma emission without neutron evaporation—using a lead-208 target and selenium-82 projectiles. No atoms of element 116 were identified.

In late 1998, Polish physicist Robert Smolańczuk published calculations on fusing atomic nuclei to create superheavy elements, including 118 and 116. His work suggested that these elements might be made by fusing lead with krypton under carefully controlled conditions. In 1999, researchers at Lawrence Berkeley National Laboratory used these predictions and announced the discovery of elements 118 and 116 in a paper in *Physical Review Letters*, with results soon reported in *Science*. They claimed to have performed the reaction krypton-86 plus lead-208, producing oganesson-293 plus a neutron, which then decayed via alpha emission to livermorium-289. The following year, they retracted the claim after other labs could not replicate the results, and Berkeley itself also failed to do so. In June 2002, the lab’s director stated that the original discovery claim was based on data fabricated by lead author Victor Ninov. The isotope livermorium-289 was finally confirmed in 2024 at JINR.

Livermorium was first successfully synthesized on July 19, 2000, at Dubna. Scientists bombarded a curium-248 target with accelerated calcium-48 ions, producing a single atom that decayed by alpha emission with an energy of 10.54 MeV into an isotope of flerovium. The results were published in December 2000. The reaction produced livermorium-293 after three neutron emissions, which then decayed to flerovium-289. The daughter flerovium isotope matched properties of a flerovium isotope first made in June 1999, originally assigned as flerovium-288, which implied the parent livermorium was livermorium-292. Later work in December 2002 showed that the flerovium isotope was actually flerovium-289, so the livermorium atom was reassigned as livermorium-293.

During a second experiment from April to May 2001, Dubna reported two more livermorium atoms. In the same run, they also detected a decay chain matching the first observed flerovium decay from December 1998, which had been assigned to flerovium-289. No flerovium isotope with those same properties has ever been seen again, even in repeats of the same reaction. It was later determined that flerovium-289 has different decay characteristics, and the 1998 atom may have been its nuclear isomer, flerovium-289m. The observation of this isomer in the 2001 experiments could indicate the formation of a parent isomer of livermorium, livermorium-293m, or a rare, previously unseen decay branch.