Flerovium

Flerovium
Atomic number	114
Symbol	Fl
Group	14 (carbon group)
Electron configuration	[Rn] 5f14 6d10 7s2 7p2
Period	7
Main isotopes	289Fl, 288Fl, 287Fl
Block	p
Oxidation states	0, +2, +4
Wikidata	Q1302

Flerovium (pronounced FLER-oh-vee-əm) is a synthetic superheavy element with atomic number 114. It is the heaviest known member of the carbon group (group 14) in the periodic table No stable or naturally occurring isotopes of flerovium exist – only a few atoms have ever been produced in nuclear laboratories. Relativistic effects (due to its very high atomic number) are predicted to give Fl an almost “noble-gas–like” or extremely volatile character In the laboratory it has only been observed atom-by-atom, but theory implies it melts at a low temperature (around 340 K) and vaporizes easily, unlike its lighter homologue lead Flerovium’s properties continue to challenge periodic trends and chemical intuition.

Overview and Key Facts

• Symbol and atomic number: Fl, Z = 114. Flerovium lies below lead (Pb) in group 14 of the periodic table
• Periodic placement: It is a p-block element in Period 7 (carbon group). It is often classified as a post-transition metal.
• Atomic weight: Being entirely synthetic, Fl has no fixed “standard” atomic weight. The atomic mass of the longest-lived isotope (around 289) is about 289.19 u which is sometimes given in brackets (e.g. [289 like other short-lived transactinides.
• Oxidation states: Chemistry theory predicts Fl will preferentially use a +2 oxidation state (analogous to Pb^2+), and that +4 is strongly disfavored In practice all compounds of Fl would be extremely unstable. (A +1 state or negative states have not been observed or predicted.)
• Phase at STP: No macroscopic amount has been isolated, so its true phase at standard temperature and pressure is unknown. Calculations suggest a very low melting point (~340 K) and boiling point (~420 K) In other words, if bulk flerovium could be made it would likely be a liquid or easily vaporized metal near room temperature – a striking departure from lead.

Atomic Structure and Electron Configuration

Flerovium has 114 electrons with a ground-state configuration [Rn] 5f^14 6d^10 7s^2 7p^2 Like all group-14 elements it nominally has four valence electrons, but for Fl those electrons feel extreme relativistic effects. The 7s and 7p orbitals (especially the 7p1/2 subshell) are strongly stabilized by spin–orbit coupling. The 7p orbital splits into a spherical 7p1/2 and a larger 7p3/2, with a large energy gap (~3 eV) between them As a result, Fl’s outer 7s^2 7p^2 shell is effectively very tightly bound. The first excitation of Fl (from the closed-shell^1S0 ground state to an excited^3P1 state) would require over 3 eV These strong relativistic effects make Fl’s valence shell behave more like a closed noble-gas shell than a typical metallic one. Indeed, early calculations concluded that promoting Fl’s electrons into bonding configurations is very costly, making it unusually inert

Quantitatively, the predicted first ionization energy of flerovium is around 8.5 eV (second only to lead within the group, reflecting its closed-like shell). There are no experimental values for Fl’s electronegativity, but by analogy to lead and its high ionization energy it would likely be fairly high (in the 1.7–1.8 range on the Pauling scale, similar to Pb). Theoretical calculations estimate Fl’s single-bond covalent radius at roughly 143 pm (compare Pb≈175 pm), and a van der Waals radius on the order of 200 pm. (Direct measurements of atomic size are of course impossible.) Overall, Fl follows the trend of increasing inert-pair effects down the group: its 7s^2 electrons are deeply bound and contribute little to bonding, so the chemistry is centered on the 7p electrons (which themselves are stabilized).

Isotopes and Nuclear Properties

All isotopes of flerovium are artificial and very short-lived. Known nuclides range roughly from ^285Fl up to ^289Fl (and possibly ^290Fl), with mass numbers in the high 200s. The longest-lived isotope observed so far is ^289Fl, with a half-life on the order of 2–3 seconds For example, ^289Fl (electron-capture and β^+ decay are negligible) decays by ~10.0 MeV α-emission to ^285Cn with >94% probability (the rest decays by spontaneous fission at a very low probability). Another example, ^285Fl has a half-life of only about 0.10 s and decays mainly by ~10.6 MeV α to ^281Cn (with a small fission branch). These odd-mass isotopes have nonzero nuclear spins (e.g. ^289Fl has spin 5/2^+ ^285Fl is 3/2^+ Other isotopes (like ^286–^288Fl) have similarly short lifetimes (milliseconds to seconds) and decay chains via sequential α-decays and occasional fission. The predicted island of stability at N=184 suggests that much heavier Fl isotopes (e.g. ^298Fl) might live much longer (theory predicts ^298Fl could have a half-life of days but such neutron-rich isotopes have not yet been synthesized. In practice, no isotope of Fl is useful for dating or long-term applications – they exist only briefly after creation and disappear by radioactive decay.

Allotropes and Typical Compounds

No allotropes or bulk forms of flerovium have ever been observed, and none are expected since no macroscopic sample exists. If a macroscopic metal could be formed, it would likely have a dense, close-packed structure (fcc or hcp) like lead, but with much weaker bonding. Chemically, Fl’s inertness means very few compounds are predicted. As a group-14 element analog of lead, one might imagine Fl forming dihalides or oxides in the +2 state. In fact, relativistic calculations suggest that Flerovium(II) fluoride (FlF2) and monoxide (FlO) are the only simple Fl compounds with any thermodynamic stability No FlX4 (e.g. FlF4) or higher-oxidation compounds are expected to exist. All other Fl–element bonds would be extremely weak and likely transient. For example, theoreticians have considered FlCl2 by analogy to PbCl2, but even such a compound would see only very weak bonding. No hydrides, sulfides, or complex salts of Fl have been detected or are expected. In practice, the only “chemistry” studied has been gas-phase interactions of single atoms with surfaces. These experiments show that Fl atoms adhere only very weakly to other materials. For instance, a gas-chromatography study found that the adsorption enthalpy of Fl on gold was only about 34 kJ/mol (exceedingly low – this is dominated by van der Waals forces). In other words, Fl adsorbs to surfaces almost as feebly as a noble gas.

Physical Properties

Because flerovium has never been produced in bulk, its physical properties are entirely theoretical. Using the best relativistic calculations, Fl is predicted to be a very dense, soft metal. Typical estimates put its density on the order of 11–14 g/cm^3 (by comparison, lead is 11.34 g/cm^3). In high-energy physics tables a value of ~14.0 g/cm^3 is often assumed Calculated cohesive (bulk binding) energy is low (around –0.5 eV per atom) consistent with a weakly bonded metal. The remarkable feature is Fl’s low melting point: calculations suggest Fl may melt around 340 K (≈67 °C) and boil at ~420 K (≈147 °C) If true, ninimum, flerovium would be a liquid at or near room temperature (much lower than lead’s 600 K melting point). Crystal-structure studies find that face-centered cubic and hexagonal close-packed lattice energies are nearly equal, but uncertainties remain.

Electrically, Fl is predicted to be a poor metal or even a small-gap semiconductor. Some band-structure models give a band gap ~0.8 eV in a hexagonal lattice implying semiconducting behavior rather than good metallic conductivity. In any case, no conductivity measurements exist. No atomic spectral lines have been observed (the atom’s transitions lie far into the UV). Theory finds the lowest excited state requiring >3 eV so Fl’s optical/UV emission would be in the far-UV. One nuclear-spectroscopy experiment did detect gamma transitions along a decay chain from Fl, identifying excited nuclear levels but that probes nuclear, not atomic, energy levels.

Most importantly, all experimental evidence points to extraordinary volatility. Even single Fl atoms have been observed to travel through gas-flow columns under conditions that condense normal metals. For example, initial gas-solid chromatography studies showed Fl atoms barely stuck to a gold surface – a result consistent with a noble-gas-like volatility In one experiment the observed adsorption enthalpy on gold was so small (≈34 kJ/mol) that Fl atoms effectively behaved like a “super-heavy noble gas.” Another more recent test actually saw Fl atoms depositing on gold at room temperature, hinting at somewhat stronger (metal-like) adsorption Even in that case, the binding energy is predicted to be only a few tenths of an eV In short, Fl’s physical behavior is dominated by weak London forces and relativistic inertness, making it a highly volatile metal.

Chemical Reactivity and Trends

In chemical terms, flerovium is exceptionally inert. The relativistic stabilization of its valence electrons means that Fl atoms do not easily form bonds. The element’s behavior has been probed by “one-atom-at-a-time” gas-phase experiments, which show only very weak interactions with surfaces or reagents According to periodic trends, one would compare Fl to lead or tin; however, the inert-pair effect (and additional relativistic effects) is far stronger in Fl. Most predictions portray Fl as less reactive than any lighter carbon-group element. Indeed, theoretical models by Pitzer (1975) and others concluded that both copernicium (Cn) and flerovium should be “very inert, like noble gases” because promoting electrons into bonding orbitals would cost more energy than could be gained

Accordingly, flerovium would be a very poor reducing agent (it is hard to oxidize) and it would resist complexation or acid–base reactions. For instance, no solid oxide or halide of Fl is known – almost the only possible stable neutral compounds are FlF2 and FlO (both +2 compounds) Lead analogs like PbO2 or PbCl4 are not expected; Fl^{+4} salts would be thermodynamically unstable. In aqueous terms, even if Fl^2+ ions could exist momentarily, they would hydrolyze immediately (if sample size were not the problem). Likewise, Fl is not expected to form organometallic complexes or coordination compounds in any usual way.

On metal surfaces, Fl shows only feeble bonding. The adsorption of a single Fl atom on a gold surface is calculated to be only ~0.5 eV (much lower than for any common metal) In practical terms, Fl atoms in a gas stream essentially “skim” over surfaces rather than sticking chemically. Thus the element is placed effectively at the bottom of any electrochemical or reactivity series. In spirit it resembles the late noble metals (Hg, Cn) in its unreactivity. There is no known corrosion or passivation chemistry of Fl: if an isolated Fl atom landed on an oxide or reacted with oxygen, it might form FlO briefly, but it would not form a stable oxide layer like many metals.

In summary, whether viewed as a lead-like metal or as a heavy noble-metal analog, Fl’s chemistry is dominated by weak, dispersion Bonding. Experiments have been limited to adsorption studies and these confirm that flerovium bonds hardly at all under typical conditions. All lighter analogs suggest that Fl would chiefly exhibit a +2 oxidation state at most; otherwise it is essentially inert.

Occurrence and Production

Flerovium is not found in nature. Any primordial atoms would have long since decayed, and there are no known geological processes that produce element 114 in significant amounts. It is only produced artificially in particle accelerators. The first synthesis was achieved in 1998–1999 at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, by bombarding plutonium targets with calcium-48 ions For example, a ^{244}Pu target hit by ^{48}Ca ions can fuse to ^{292}Fl, which then loses neutrons to form isotopes like ^{289}Fl. The yields are extremely low (a few atoms over weeks of beam time). Subsequent syntheses have used various Pu isotopes (and even mixtures or neighboring elements like Am or Cm) to produce ^{285–289}Fl by 2–5 neutron evaporation channels.

Leading laboratories that have produced flerovium include JINR Dubna (Russia), often collaborating with Lawrence Livermore National Laboratory (USA) as well as GSI Darmstadt (Germany) and the U.S. national laboratories. In 2009, independent teams at Berkeley (USA) and GSI confirmed isotopes ^{286–289}Fl Today, only a handful of research groups have the equipment (intense beams of ^{48}Ca and actinide targets) necessary to create just a few atoms of flerovium at a time. Because of the extremely short half-lives, the very small number of atoms is detected on-the-fly by their decay signatures in recoil separators.

In astrophysical terms, flerovium would be exceedingly rare. It might be briefly formed by rapid neutron capture (r-process) in supernovae or neutron-star mergers, but even if so such isotopes (especially heavy Fl) would decay long before any detection. Thus cosmic or terrestrial abundance of 114 is effectively zero.

Applications and Technology

There are no practical applications of flerovium outside of scientific research. Its isotopes last only seconds, and only a few atoms have ever existed at once, so it has no industrial, medical, or commercial uses. Flerovium’s role is purely in fundamental studies: exploring the limits of the periodic table, testing nuclear shell models (the “island of stability”), and probing relativistic chemistry theories. For example, chemists study Fl to see if it truly behaves like a noble gas or noble metal analog But unlike lead (used in batteries, radiation shielding, etc.), flerovium serves only as a research curiosity. Its fleeting existence limits it to the laboratory, and it has no engineered applications or products.

Biology, Environment, and Safety

Flerovium has no biological function. In fact, it is too short-lived to interact with any living system meaningfully. The longest-lived isotopes survive only seconds and decay rapidly into lighter elements. Since no appreciable quantity of Fl can accumulate, it poses no environmental risk in the usual sense.

From a safety perspective, any exposure to flerovium would involve intense ionizing radiation. Its observed decays are nearly all alpha particles (plus some spontaneous fission). For example, ^{289}Fl decays by emitting a ~9.95 MeV alpha particle If a milligram of ^{289}Fl could be amassed (a purely hypothetical scenario), its alpha radioactivity would be extremely high (tens of petabecquerels). However, in practice only isolated atoms exist for a few seconds, so ordinary radiation-safety limits don’t really apply. Handling flerovium is done with remote instruments; any chemical toxicity (if any) is irrelevant compared to the lethal radioactivity of even a few atoms.

In summary, there is no natural exposure or environmental cycling of Fl. If produced, it would quickly decay to lead-group elements (Cn, Ds, etc.). As with other transactinides, the main hazard is the radiation from its decays, but this is only of academic concern given the minute quantities.

History and Etymology

The first reports of element 114 came from Dubna, Russia, in the late 1990s. In 1999 the JINR team (in collaboration with Lawrence Livermore Lab) bombarded plutonium targets with ^{48}Ca, observing characteristic decay chains later attributed to new isotopes of Z=114 This work, along with confirmatory experiments, led IUPAC’s Joint Working Party in 2011 to credit the JINR/LLNL team with the discovery of 114

Initially known by the temporary systematic name “ununquadium” (Uuq), element 114 was officially named flerovium (Fl) in May 2012 The name honors Georgiy N. Flerov (1913–1990), a pioneering Russian physicist who founded the Flerov Laboratory of Nuclear Reactions at JINR (where the element was discovered) (Flerov is best known for discovering spontaneous fission and for early heavy-ion research.) The naming citation explicitly notes that the name recognizes both Flerov and the FLNR institute in Dubna

Before adoption of the name, proposals and informal names included “eka–lead” (by analogy with Mendeleev’s predictions) and “atomic number 114”. The discovery of flerovium marked an important achievement in the search for superheavy elements and the “island of stability.” It confirmed decades of theoretical work suggesting that nuclear shell effects could stabilize elements beyond lead. Subsequent nuclear experiments in the 2000s (at GSI and Berkeley) mapped out more isotopes of 114 Throughout its short history, flerovium has been a symbol of modern nuclear and relativistic chemistry, illustrating how element discovery and theory intertwine.

Data Table

Property	Value
Atomic number (Z)	114
Element name	Flerovium
Symbol	Fl
Period / Group / Block	7 / 14 (carbon group) / p-block
Atomic mass	[289.187(5 g·mol^–1
Electron configuration	[Rn] 5f^14 6d^10 7s^2 7p^2
Valence electrons	4 (two 7s, two 7p)
Common oxidation state(s)	+2 (predicted)
Phase at STP	— (not applicable; predicted liquid at ~340 K)
Density	~14 g·cm^–3 (theoretical)
Melting point	~340 K (67 °C)
Boiling point	~420 K (147 °C)
Covalent radius	~143 pm (predicted)
First ionization energy	~8.5 eV
Most stable isotope	^289Fl, t1/2 ≈ 2.4 s
Discovery	Synthesized 1998–99 (Dubna, Russia); named 2012

Each entry above is drawn from theoretical predictions or the limited experimental data. The values in brackets for atomic mass and isotope refer to measured values from specific Fl nuclides (No stable atomic weight is defined for such a transient element.)

Sources: Authoritative nuclear and element data compilations and research papers