Flerovium [FLEA-ROH-VEE-UM] is the superheavy artificial chemical element with the symbol Fl and atomic number 114. It is an extremely radioactive element that can only be created in the laboratory and does not occur in nature. The element is named after the Flerov Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research in Dubna, Russia, where the element was discovered in 1998. The name of the laboratory, in turn, honors the Russian physicist Georgy Flyorov. The name was adopted by IUPAC on May 30, 2012 (Right after my birthday!).
In the periodic table of the elements, it is a transactinide element in the p-block. It is a member of the 7th period and is currently placed as the heaviest known member of the carbon group. Initial chemical studies performed in 2007–2008 indicated that flerovium was unexpectedly volatile for a group 14 element; in preliminary results it even seemed to exhibit properties similar to those of the noble gases. More recent results show that flerovium's reaction with gold is similar to that of copernicium, showing that it is a very volatile element that may even be gaseous at standard temperature and pressure, and that while it would show metallic properties, consistent with it being the heavier homologue of lead, it would also be the least reactive metal in group 14.
About 80 atoms of flerovium have been observed to date: 50 were synthesized directly, while the rest were made from the radioactive decay of even heavier elements. All of these flerovium atoms have been shown to have mass numbers from 285 to 289. The most stable known flerovium isotope, flerovium-289, has a half-life of around 2.6 seconds, but it is possible that this flerovium isotope may have a nuclear isomer with a longer half-life of 66 seconds; this would be one of the longest half-lives of any isotope of a superheavy element. Flerovium is predicted to be near the center of the theorized island of stability, and it is expected that heavier flerovium isotopes, especially the possibly doubly magic flerovium-298, may have even longer half-lives.
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Historical information
Only one atom of flerovium (289114Fl)has ever been made (through a nuclear reaction involving fusing a calcium atom with a plutonium atom) isolation of an observable quantity has never been achieved, and may well never be. The discovery was reported informally in January 1999 following experiments towards the end of December 1998 involving scientists at Dubna (Joint Institute for Nuclear Research) in Russia and the Lawrence Livermore National Laboratory, USA.
From the late 1940s to the early 1960s, the early days of the synthesis of heavier and heavier transuranium elements, it was predicted that since such heavy elements did not occur in nature, they would have shorter and shorter half-lives to spontaneous fission, until they stopped being able to exist altogether at around element 108. Initial work in the synthesis of the actinides appeared to confirm this. However, the nuclear shell model was introduced in the late 1960s, which stated that the protons and neutrons formed shells within a nucleus, just like electrons forming electron shells within an atom. The noble gases are unreactive due to their having full electron shells; thus it was theorized that elements with full nuclear shells – having so-called "magic" numbers of protons or neutrons – would be stabilized against radioactive decay. A doubly-magic isotope, having magic numbers of both protons and neutrons, would be especially stabilized, and it was calculated that the next doubly-magic isotope after lead-208 would be flerovium-298 with 114 protons and 184 neutrons, which would form the center of a so-called "island of stability". This island of stability, supposedly centering around elements 112 to element 118, would come just after a long "sea of instability" from elements 101 to 111, and the flerovium isotopes in it were speculated in 1966 to have half-lives in excess of a hundred million years. It was not until thirty years later, however, that the first isotopes of flerovium would be synthesized. More recent work, however, suspects that the local islands of stability around hassium and flerovium are due to these nuclei being respectively deformed and oblate, which make them resistant towards spontaneous fission, and that the true island of stability for spherical nuclei occurs at around unbibium-306 (with 122 protons and 184 neutrons.
Flerovium was first synthesized in December 1998 by a team of scientists at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia led by Yuri Oganessian, who bombarded a target of plutonium-244 with accelerated nuclei of calcium-48:
A single atom of flerovium, decaying by alpha emission with a half-life of 30 seconds, was detected. This observation was assigned to the isotope flerovium-289 and was subsequently published in January 1999. However, the decay chain observed has not been repeated and the exact identity of this activity is unknown, although it is possible that it is due to a metastable isomer, namely 289mFl.
Glenn T. Seaborg, a scientist at the Lawrence Berkeley National Laboratory who had been involved in work to synthesize such superheavy elements, stated in December 1997 that "one of his longest-lasting and most cherished dreams was to see one of these magic elements." He had, by this time, suffered a massive stroke which affected his memory. He received notice of the synthesis of flerovium from his colleague Albert Ghiorso soon after its publication 1999. Ghiorso later recalled:
“I wanted Glenn to know, so I went to his bedside and told him. I thought I saw a gleam in his eye, but the next day when I went to visit him he didn't remember seeing me. As a scientist, he had died when he had that stroke.” — Albert Ghiorso
Physical properties
- Melting point: 340 K; 67 C; 160 F (predicted)
- Boiling point: 420 K; 147 C; 297 F (predicted)
- Density of solid: 14 (predicted) g cm-3
- Heat of vaporization: 38 (predicted) kJ mol-1
Orbital properties
- Ground state electron configuration: [Rn].5f14.6d10.7s2.7p2 (a guess based upon that of lead)
- Shell structure: 2.8.18.32.32.18.4
- Term symbol: 3P0 (a guess based upon guessed electronic structure)
- Pauling electronegativity: no data (Pauling units)
- First ionization energy: no data kJ mol-1
- Second ionization energy: no data kJ mol-1
Isolation
Isolation: as only about three atoms of flerovium has ever been made (through nuclear reaction involving fusing a calcium atom with a plutonium atom) isolation of an observable quantity has never been achieved, and may well never be.
24494Pu + 4820Ca → 288114Fl + 4 1n
24494Pu + 4820Ca → 289114Fl + 3 1n
The element decomposes through the emission of an α-particle to form element 112, copernicium, with a half-life of about 30 seconds for 289114Fl and 2 seconds for 288114Fl.
A different isotope of element 114, 285114Fl, is observed as a decomposition product of the recently observed element 118. Elements 118 and 116 were identified by accelerating a beam of krypton-86 (8636Kr) ions to an energy of 449 million electron volts and directing the beam onto targets of lead-208 (20882Pb). After 11 days work, just three atoms of the new element were identified. The production rates for element 118 are approximately one in every 1012 interactions.
20882Pb + 8636Kr → 293118Uuo + 1n
Element 118 nucleus decays less than a millisecond after its formation by emitting an α-particle. This results in an isotope of flerovium (mass number 289, containing 116 protons and 173 neutrons). This isotope of element 116 is also radioactive and undergoes further α-decay processes to an isotope of flerovium, element 114, and so on down to at least element 106.
293118Uuo → 289116Lv + 42He (0.12 milliseconds)
289116Lv → 285114Fl + 42He (0.60 milliseconds)
285114Fl → 281112Cn + 42He (0.58 milliseconds)
281112Cn → 277110Ds + 42He (0.89 milliseconds)
277110Rg → 273108Hs + 42He (3 milliseconds)
273108Hs → 269106Sg + 42He (1200 milliseconds)
