Meitnerium | |||||||||||||||||||||||||||||||
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Pronunciation | |||||||||||||||||||||||||||||||
Mass number | [278] (data not decisive) [a] | ||||||||||||||||||||||||||||||
Meitnerium in the periodic table | |||||||||||||||||||||||||||||||
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Atomic number (Z) | 109 | ||||||||||||||||||||||||||||||
Group | group 9 | ||||||||||||||||||||||||||||||
Period | period 7 | ||||||||||||||||||||||||||||||
Block | d-block | ||||||||||||||||||||||||||||||
Electron configuration | [ Rn ] 5f14 6d7 7s2(predicted) [6] [7] | ||||||||||||||||||||||||||||||
Electrons per shell | 2, 8, 18, 32, 32, 15, 2 (predicted) | ||||||||||||||||||||||||||||||
Physical properties | |||||||||||||||||||||||||||||||
Phase at STP | solid (predicted) [8] | ||||||||||||||||||||||||||||||
Density (near r.t.) | 27–28 g/cm3(predicted) [9] [10] | ||||||||||||||||||||||||||||||
Atomic properties | |||||||||||||||||||||||||||||||
Oxidation states | common: (none) (+1), (+3), (+6) [6] | ||||||||||||||||||||||||||||||
Ionization energies | |||||||||||||||||||||||||||||||
Atomic radius | empirical:128 pm (predicted) [6] [11] | ||||||||||||||||||||||||||||||
Covalent radius | 129 pm(estimated) [12] | ||||||||||||||||||||||||||||||
Other properties | |||||||||||||||||||||||||||||||
Natural occurrence | synthetic | ||||||||||||||||||||||||||||||
Crystal structure | face-centered cubic (fcc) (predicted) [8] | ||||||||||||||||||||||||||||||
Magnetic ordering | paramagnetic (predicted) [13] | ||||||||||||||||||||||||||||||
CAS Number | 54038-01-6 | ||||||||||||||||||||||||||||||
History | |||||||||||||||||||||||||||||||
Naming | after Lise Meitner | ||||||||||||||||||||||||||||||
Discovery | Gesellschaft für Schwerionenforschung (1982) | ||||||||||||||||||||||||||||||
Isotopes of meitnerium | |||||||||||||||||||||||||||||||
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Meitnerium is a synthetic chemical element; it has symbol Mt and atomic number 109. It is an extremely radioactive synthetic element (an element not found in nature, but can be created in a laboratory). The most stable known isotope, meitnerium-278, has a half-life of 4.5 seconds, although the unconfirmed meitnerium-282 may have a longer half-life of 67 seconds. The element was first synthesized in August 1982 by the GSI Helmholtz Centre for Heavy Ion Research near Darmstadt, Germany, and it was named after Lise Meitner in 1997.
In the periodic table, meitnerium is a d-block transactinide element. It is a member of the 7th period and is placed in the group 9 elements, although no chemical experiments have yet been carried out to confirm that it behaves as the heavier homologue to iridium in group 9 as the seventh member of the 6d series of transition metals. Meitnerium is calculated to have properties similar to its lighter homologues, cobalt, rhodium, and iridium.
A superheavy [b] atomic nucleus is created in a nuclear reaction that combines two other nuclei of unequal size [c] into one; roughly, the more unequal the two nuclei in terms of mass, the greater the possibility that the two react. [19] The material made of the heavier nuclei is made into a target, which is then bombarded by the beam of lighter nuclei. Two nuclei can only fuse into one if they approach each other closely enough; normally, nuclei (all positively charged) repel each other due to electrostatic repulsion. The strong interaction can overcome this repulsion but only within a very short distance from a nucleus; beam nuclei are thus greatly accelerated in order to make such repulsion insignificant compared to the velocity of the beam nucleus. [20] The energy applied to the beam nuclei to accelerate them can cause them to reach speeds as high as one-tenth of the speed of light. However, if too much energy is applied, the beam nucleus can fall apart. [20]
Coming close enough alone is not enough for two nuclei to fuse: when two nuclei approach each other, they usually remain together for about 10−20 seconds and then part ways (not necessarily in the same composition as before the reaction) rather than form a single nucleus. [20] [21] This happens because during the attempted formation of a single nucleus, electrostatic repulsion tears apart the nucleus that is being formed. [20] Each pair of a target and a beam is characterized by its cross section—the probability that fusion will occur if two nuclei approach one another expressed in terms of the transverse area that the incident particle must hit in order for the fusion to occur. [d] This fusion may occur as a result of the quantum effect in which nuclei can tunnel through electrostatic repulsion. If the two nuclei can stay close past that phase, multiple nuclear interactions result in redistribution of energy and an energy equilibrium. [20]
External videos | |
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Visualization of unsuccessful nuclear fusion, based on calculations from the Australian National University [23] |
The resulting merger is an excited state [24] —termed a compound nucleus—and thus it is very unstable. [20] To reach a more stable state, the temporary merger may fission without formation of a more stable nucleus. [25] Alternatively, the compound nucleus may eject a few neutrons, which would carry away the excitation energy; if the latter is not sufficient for a neutron expulsion, the merger would produce a gamma ray. This happens in about 10−16 seconds after the initial nuclear collision and results in creation of a more stable nucleus. [25] The definition by the IUPAC/IUPAP Joint Working Party (JWP) states that a chemical element can only be recognized as discovered if a nucleus of it has not decayed within 10−14 seconds. This value was chosen as an estimate of how long it takes a nucleus to acquire electrons and thus display its chemical properties. [26] [e]
The beam passes through the target and reaches the next chamber, the separator; if a new nucleus is produced, it is carried with this beam. [28] In the separator, the newly produced nucleus is separated from other nuclides (that of the original beam and any other reaction products) [f] and transferred to a surface-barrier detector, which stops the nucleus. The exact location of the upcoming impact on the detector is marked; also marked are its energy and the time of the arrival. [28] The transfer takes about 10−6 seconds; in order to be detected, the nucleus must survive this long. [31] The nucleus is recorded again once its decay is registered, and the location, the energy, and the time of the decay are measured. [28]
Stability of a nucleus is provided by the strong interaction. However, its range is very short; as nuclei become larger, its influence on the outermost nucleons (protons and neutrons) weakens. At the same time, the nucleus is torn apart by electrostatic repulsion between protons, and its range is not limited. [32] Total binding energy provided by the strong interaction increases linearly with the number of nucleons, whereas electrostatic repulsion increases with the square of the atomic number, i.e. the latter grows faster and becomes increasingly important for heavy and superheavy nuclei. [33] [34] Superheavy nuclei are thus theoretically predicted [35] and have so far been observed [36] to predominantly decay via decay modes that are caused by such repulsion: alpha decay and spontaneous fission. [g] Almost all alpha emitters have over 210 nucleons, [38] and the lightest nuclide primarily undergoing spontaneous fission has 238. [39] In both decay modes, nuclei are inhibited from decaying by corresponding energy barriers for each mode, but they can be tunneled through. [33] [34]
Alpha particles are commonly produced in radioactive decays because the mass of an alpha particle per nucleon is small enough to leave some energy for the alpha particle to be used as kinetic energy to leave the nucleus. [41] Spontaneous fission is caused by electrostatic repulsion tearing the nucleus apart and produces various nuclei in different instances of identical nuclei fissioning. [34] As the atomic number increases, spontaneous fission rapidly becomes more important: spontaneous fission partial half-lives decrease by 23 orders of magnitude from uranium (element 92) to nobelium (element 102), [42] and by 30 orders of magnitude from thorium (element 90) to fermium (element 100). [43] The earlier liquid drop model thus suggested that spontaneous fission would occur nearly instantly due to disappearance of the fission barrier for nuclei with about 280 nucleons. [34] [44] The later nuclear shell model suggested that nuclei with about 300 nucleons would form an island of stability in which nuclei will be more resistant to spontaneous fission and will primarily undergo alpha decay with longer half-lives. [34] [44] Subsequent discoveries suggested that the predicted island might be further than originally anticipated; they also showed that nuclei intermediate between the long-lived actinides and the predicted island are deformed, and gain additional stability from shell effects. [45] Experiments on lighter superheavy nuclei, [46] as well as those closer to the expected island, [42] have shown greater than previously anticipated stability against spontaneous fission, showing the importance of shell effects on nuclei. [h]
Alpha decays are registered by the emitted alpha particles, and the decay products are easy to determine before the actual decay; if such a decay or a series of consecutive decays produces a known nucleus, the original product of a reaction can be easily determined. [i] (That all decays within a decay chain were indeed related to each other is established by the location of these decays, which must be in the same place.) [28] The known nucleus can be recognized by the specific characteristics of decay it undergoes such as decay energy (or more specifically, the kinetic energy of the emitted particle). [j] Spontaneous fission, however, produces various nuclei as products, so the original nuclide cannot be determined from its daughters. [k]
The information available to physicists aiming to synthesize a superheavy element is thus the information collected at the detectors: location, energy, and time of arrival of a particle to the detector, and those of its decay. The physicists analyze this data and seek to conclude that it was indeed caused by a new element and could not have been caused by a different nuclide than the one claimed. Often, provided data is insufficient for a conclusion that a new element was definitely created and there is no other explanation for the observed effects; errors in interpreting data have been made. [l]Meitnerium was first synthesized on August 29, 1982, by a German research team led by Peter Armbruster and Gottfried Münzenberg at the Institute for Heavy Ion Research (Gesellschaft für Schwerionenforschung) in Darmstadt. [57] The team bombarded a target of bismuth-209 with accelerated nuclei of iron-58 and detected a single atom of the isotope meitnerium-266: [58]
This work was confirmed three years later at the Joint Institute for Nuclear Research at Dubna (then in the Soviet Union). [58]
Using Mendeleev's nomenclature for unnamed and undiscovered elements, meitnerium should be known as eka-iridium . In 1979, during the Transfermium Wars (but before the synthesis of meitnerium), IUPAC published recommendations according to which the element was to be called unnilennium (with the corresponding symbol of Une), [59] a systematic element name as a placeholder, until the element was discovered (and the discovery then confirmed) and a permanent name was decided on. Although widely used in the chemical community on all levels, from chemistry classrooms to advanced textbooks, the recommendations were mostly ignored among scientists in the field, who either called it "element 109", with the symbol of E109, (109) or even simply 109, or used the proposed name "meitnerium". [6]
The naming of meitnerium was discussed in the element naming controversy regarding the names of elements 104 to 109, but meitnerium was the only proposal and thus was never disputed. [60] [61] The name meitnerium (Mt) was suggested by the GSI team in September 1992 in honor of the Austrian physicist Lise Meitner, a co-discoverer of protactinium (with Otto Hahn), [62] [63] [64] [65] [66] and one of the discoverers of nuclear fission. [67] In 1994 the name was recommended by IUPAC, [60] and was officially adopted in 1997. [61] It is thus the only element named specifically after a non-mythological woman (curium being named for both Pierre and Marie Curie). [68]
Meitnerium has no stable or naturally occurring isotopes. Several radioactive isotopes have been synthesized in the laboratory, either by fusing two atoms or by observing the decay of heavier elements. Eight different isotopes of meitnerium have been reported with mass numbers 266, 268, 270, and 274–278, two of which, meitnerium-268 and meitnerium-270, have unconfirmed metastable states. A ninth isotope with mass number 282 is unconfirmed. Most of these decay predominantly through alpha decay, although some undergo spontaneous fission. [69]
Isotope | Half-life [m] | Decay mode | Discovery year | Discovery reaction | |
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Value | ref | ||||
266Mt | 2.0 ms | [3] | α, SF | 1982 | 209Bi(58Fe,n) |
268Mt | 23 ms | [3] | α | 1994 | 272Rg(—,α) |
270Mt | 800 ms | [3] | α | 2004 | 278Nh(—,2α) |
274Mt | 640 ms | [4] | α | 2006 | 282Nh(—,2α) |
275Mt | 20 ms | [4] | α | 2003 | 287Mc(—,3α) |
276Mt | 620 ms | [4] | α | 2003 | 288Mc(—,3α) |
277Mt | 5 ms | [70] | SF | 2012 | 293Ts(—,4α) |
278Mt | 4.5 s | [70] | α | 2010 | 294Ts(—,4α) |
282Mt [n] | 1.1 min | [5] | α | 1998 | 290Fl(e−,νe2α) |
All meitnerium isotopes are extremely unstable and radioactive; in general, heavier isotopes are more stable than the lighter. The most stable known meitnerium isotope, 278Mt, is also the heaviest known; it has a half-life of 4.5 seconds. The unconfirmed 282Mt is even heavier and appears to have a longer half-life of 67 seconds. With a half-life of 0.8 seconds, the next most stable known isotope is 270Mt. [3] The isotopes 276Mt and 274Mt have half-lives of 0.62 and 0.64 seconds respectively. [4]
The isotope 277Mt, created as the final decay product of 293Ts for the first time in 2012, was observed to undergo spontaneous fission with a half-life of 5 milliseconds. Preliminary data analysis considered the possibility of this fission event instead originating from 277Hs, for it also has a half-life of a few milliseconds, and could be populated following undetected electron capture somewhere along the decay chain. [71] [72] This possibility was later deemed very unlikely based on observed decay energies of 281Ds and 281Rg and the short half-life of 277Mt, although there is still some uncertainty of the assignment. [72] Regardless, the rapid fission of 277Mt and 277Hs is strongly suggestive of a region of instability for superheavy nuclei with N = 168–170. The existence of this region, characterized by a decrease in fission barrier height between the deformed shell closure at N = 162 and spherical shell closure at N = 184, is consistent with theoretical models. [71]
Other than nuclear properties, no properties of meitnerium or its compounds have been measured; this is due to its extremely limited and expensive production [o] and the fact that meitnerium and its parents decay very quickly. Properties of meitnerium metal remain unknown and only predictions are available.
Meitnerium is the seventh member of the 6d series of transition metals, and should be much like the platinum group metals. [65] Calculations on its ionization potentials and atomic and ionic radii are similar to that of its lighter homologue iridium, thus implying that meitnerium's basic properties will resemble those of the other group 9 elements, cobalt, rhodium, and iridium. [6]
Prediction of the probable chemical properties of meitnerium has not received much attention recently. Meitnerium is expected to be a noble metal. The standard electrode potential for the Mt3+/Mt couple is expected to be 0.8 V. Based on the most stable oxidation states of the lighter group 9 elements, the most stable oxidation states of meitnerium are predicted to be the +6, +3, and +1 states, with the +3 state being the most stable in aqueous solutions. In comparison, rhodium and iridium show a maximum oxidation state of +6, while the most stable states are +4 and +3 for iridium and +3 for rhodium. [6] The oxidation state +9, represented only by iridium in [IrO4]+, might be possible for its congener meitnerium in the nonafluoride (MtF9) and the [MtO4]+ cation, although [IrO4]+ is expected to be more stable than these meitnerium compounds. [74] The tetrahalides of meitnerium have also been predicted to have similar stabilities to those of iridium, thus also allowing a stable +4 state. [75] It is further expected that the maximum oxidation states of elements from bohrium (element 107) to darmstadtium (element 110) may be stable in the gas phase but not in aqueous solution. [6]
Meitnerium is expected to be a solid under normal conditions and assume a face-centered cubic crystal structure, similarly to its lighter congener iridium. [8] It should be a very heavy metal with a density of around 27–28 g/cm3, which would be among the highest of any of the 118 known elements. [9] [10] Meitnerium is also predicted to be paramagnetic. [13]
Theoreticians have predicted the covalent radius of meitnerium to be 6 to 10 pm larger than that of iridium. [76] The atomic radius of meitnerium is expected to be around 128 pm. [11]
Meitnerium is the first element on the periodic table whose chemistry has not yet been investigated. Unambiguous determination of the chemical characteristics of meitnerium has yet to have been established [77] [78] due to the short half-lives of meitnerium isotopes [6] and a limited number of likely volatile compounds that could be studied on a very small scale. One of the few meitnerium compounds that are likely to be sufficiently volatile is meitnerium hexafluoride (MtF
6), as its lighter homologue iridium hexafluoride (IrF
6) is volatile above 60 °C and therefore the analogous compound of meitnerium might also be sufficiently volatile; [65] a volatile octafluoride (MtF
8) might also be possible. [6] For chemical studies to be carried out on a transactinide, at least four atoms must be produced, the half-life of the isotope used must be at least 1 second, and the rate of production must be at least one atom per week. [65] Even though the half-life of 278Mt, the most stable confirmed meitnerium isotope, is 4.5 seconds, long enough to perform chemical studies, another obstacle is the need to increase the rate of production of meitnerium isotopes and allow experiments to carry on for weeks or months so that statistically significant results can be obtained. Separation and detection must be carried out continuously to separate out the meitnerium isotopes and have automated systems experiment on the gas-phase and solution chemistry of meitnerium, as the yields for heavier elements are predicted to be smaller than those for lighter elements; some of the separation techniques used for bohrium and hassium could be reused. However, the experimental chemistry of meitnerium has not received as much attention as that of the heavier elements from copernicium to livermorium. [6] [77] [79]
The Lawrence Berkeley National Laboratory attempted to synthesize the isotope 271Mt in 2002–2003 for a possible chemical investigation of meitnerium, because it was expected that it might be more stable than nearby isotopes due to having 162 neutrons, a magic number for deformed nuclei; its half-life was predicted to be a few seconds, long enough for a chemical investigation. [6] [80] [81] However, no atoms of 271Mt were detected; [82] this isotope of meitnerium is currently unknown. [69]
An experiment determining the chemical properties of a transactinide would need to compare a compound of that transactinide with analogous compounds of some of its lighter homologues: [6] for example, in the chemical characterization of hassium, hassium tetroxide (HsO4) was compared with the analogous osmium compound, osmium tetroxide (OsO4). [83] In a preliminary step towards determining the chemical properties of meitnerium, the GSI attempted sublimation of the rhodium compounds rhodium(III) oxide (Rh2O3) and rhodium(III) chloride (RhCl3). However, macroscopic amounts of the oxide would not sublimate until 1000 °C and the chloride would not until 780 °C, and then only in the presence of carbon aerosol particles: these temperatures are far too high for such procedures to be used on meitnerium, as most of the current methods used for the investigation of the chemistry of superheavy elements do not work above 500 °C. [78]
Following the 2014 successful synthesis of seaborgium hexacarbonyl, Sg(CO)6, [84] studies were conducted with the stable transition metals of groups 7 through 9, suggesting that carbonyl formation could be extended to further probe the chemistries of the early 6d transition metals from rutherfordium to meitnerium inclusive. [85] [86] Nevertheless, the challenges of low half-lives and difficult production reactions make meitnerium difficult to access for radiochemists, though the isotopes 278Mt and 276Mt are long-lived enough for chemical research and may be produced in the decay chains of 294 Ts and 288 Mc respectively. 276Mt is likely more suitable, since producing tennessine requires a rare and rather short-lived berkelium target. [87] The isotope 270Mt, observed in the decay chain of 278Nh with a half-life of 0.69 seconds, may also be sufficiently long-lived for chemical investigations, though a direct synthesis route leading to this isotope and more precise measurements of its decay properties would be required. [81]
Bohrium is a synthetic chemical element; it has symbol Bh and atomic number 107. It is named after Danish physicist Niels Bohr. As a synthetic element, it can be created in particle accelerators but is not found in nature. All known isotopes of bohrium are highly radioactive; the most stable known isotope is 270Bh with a half-life of approximately 2.4 minutes, though the unconfirmed 278Bh may have a longer half-life of about 11.5 minutes.
Dubnium is a synthetic chemical element; it has symbol Db and atomic number 105. It is highly radioactive: the most stable known isotope, dubnium-268, has a half-life of about 16 hours. This greatly limits extended research on the element.
Hassium is a synthetic chemical element; it has symbol Hs and atomic number 108. It is highly radioactive: its most stable known isotopes have half-lives of approximately ten seconds. One of its isotopes, 270Hs, has magic numbers of protons and neutrons for deformed nuclei, giving it greater stability against spontaneous fission. Hassium is a superheavy element; it has been produced in a laboratory in very small quantities by fusing heavy nuclei with lighter ones. Natural occurrences of the element have been hypothesised but never found.
Nobelium is a synthetic chemical element; it has symbol No and atomic number 102. It is named after Alfred Nobel, the inventor of dynamite and benefactor of science. A radioactive metal, it is the tenth transuranium element, the second transfermium, and is the penultimate member of the actinide series. Like all elements with atomic number over 100, nobelium can only be produced in particle accelerators by bombarding lighter elements with charged particles. A total of twelve nobelium isotopes are known to exist; the most stable is 259No with a half-life of 58 minutes, but the shorter-lived 255No is most commonly used in chemistry because it can be produced on a larger scale.
Rutherfordium is a synthetic chemical element; it has symbol Rf and atomic number 104. It is named after physicist Ernest Rutherford. As a synthetic element, it is not found in nature and can only be made in a particle accelerator. It is radioactive; the most stable known isotope, 267Rf, has a half-life of about 48 minutes.
Seaborgium is a synthetic chemical element; it has symbol Sg and atomic number 106. It is named after the American nuclear chemist Glenn T. Seaborg. As a synthetic element, it can be created in a laboratory but is not found in nature. It is also radioactive; the most stable known isotopes have half lives on the order of several minutes.
Darmstadtium is a synthetic chemical element; it has symbol Ds and atomic number 110. It is extremely radioactive: the most stable known isotope, darmstadtium-281, has a half-life of approximately 14 seconds. Darmstadtium was first created in November 1994 by the GSI Helmholtz Centre for Heavy Ion Research in the city of Darmstadt, Germany, after which it was named.
Roentgenium is a synthetic chemical element; it has symbol Rg and atomic number 111. It is extremely radioactive and can only be created in a laboratory. The most stable known isotope, roentgenium-282, has a half-life of 130 seconds, although the unconfirmed roentgenium-286 may have a longer half-life of about 10.7 minutes. Roentgenium was first created in December 1994 by the GSI Helmholtz Centre for Heavy Ion Research near Darmstadt, Germany. It is named after the physicist Wilhelm Röntgen, who discovered X-rays. Only a few roentgenium atoms have ever been synthesized, and they have no practical application.
Livermorium is a synthetic chemical element; it has symbol Lv and atomic number 116. It is an extremely radioactive element that has only been created in a laboratory setting and has not been observed in nature. The element is named after the Lawrence Livermore National Laboratory in the United States, which collaborated with the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, to discover livermorium during experiments conducted between 2000 and 2006. The name of the laboratory refers to the city of Livermore, California, where it is located, which in turn was named after the rancher and landowner Robert Livermore. The name was adopted by IUPAC on May 30, 2012. Six isotopes of livermorium are known, with mass numbers of 288–293 inclusive; the longest-lived among them is livermorium-293 with a half-life of about 80 milliseconds. A seventh possible isotope with mass number 294 has been reported but not yet confirmed.
Oganesson is a synthetic chemical element; it has symbol Og and atomic number 118. It was first synthesized in 2002 at the Joint Institute for Nuclear Research (JINR) in Dubna, near Moscow, Russia, by a joint team of Russian and American scientists. In December 2015, it was recognized as one of four new elements by the Joint Working Party of the international scientific bodies IUPAC and IUPAP. It was formally named on 28 November 2016. The name honors the nuclear physicist Yuri Oganessian, who played a leading role in the discovery of the heaviest elements in the periodic table. It is one of only two elements named after a person who was alive at the time of naming, the other being seaborgium, and the only element whose eponym is alive as of 2024.
Unbinilium, also known as eka-radium or element 120, is a hypothetical chemical element; it has symbol Ubn and atomic number 120. Unbinilium and Ubn are the temporary systematic IUPAC name and symbol, which are used until the element is discovered, confirmed, and a permanent name is decided upon. In the periodic table of the elements, it is expected to be an s-block element, an alkaline earth metal, and the second element in the eighth period. It has attracted attention because of some predictions that it may be in the island of stability.
Moscovium is a synthetic chemical element; it has symbol Mc and atomic number 115. It was first synthesized in 2003 by a joint team of Russian and American scientists at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. In December 2015, it was recognized as one of four new elements by the Joint Working Party of international scientific bodies IUPAC and IUPAP. On 28 November 2016, it was officially named after the Moscow Oblast, in which the JINR is situated.
Tennessine is a synthetic chemical element; it has symbol Ts and atomic number 117. It has the second-highest atomic number and joint-highest atomic mass of all known elements and is the penultimate element of the 7th period of the periodic table. It is named after the U.S. state of Tennessee, where key research institutions involved in its discovery are located.
Flerovium is a synthetic chemical element; it has symbol Fl and atomic number 114. It is an extremely radioactive, superheavy element, named after the Flerov Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research in Dubna, Russia, where the element was discovered in 1999. The lab's name, in turn, honours Russian physicist Georgy Flyorov. IUPAC adopted the name on 30 May 2012. The name and symbol had previously been proposed for element 102 (nobelium), but was not accepted by IUPAC at that time.
Nihonium is a synthetic chemical element; it has the symbol Nh and atomic number 113. It is extremely radioactive: its most stable known isotope, nihonium-286, has a half-life of about 10 seconds. In the periodic table, nihonium is a transactinide element in the p-block. It is a member of period 7 and group 13.
Unbibium, also known as element 122 or eka-thorium, is a hypothetical chemical element; it has placeholder symbol Ubb and atomic number 122. Unbibium and Ubb are the temporary systematic IUPAC name and symbol respectively, which are used until the element is discovered, confirmed, and a permanent name is decided upon. In the periodic table of the elements, it is expected to follow unbiunium as the second element of the superactinides and the fourth element of the 8th period. Similarly to unbiunium, it is expected to fall within the range of the island of stability, potentially conferring additional stability on some isotopes, especially 306Ubb which is expected to have a magic number of neutrons (184).
Superheavy elements, also known as transactinide elements, transactinides, or super-heavy elements, or superheavies for short, are the chemical elements with atomic number greater than 104. The superheavy elements are those beyond the actinides in the periodic table; the last actinide is lawrencium. By definition, superheavy elements are also transuranium elements, i.e., having atomic numbers greater than that of uranium (92). Depending on the definition of group 3 adopted by authors, lawrencium may also be included to complete the 6d series.
Unbiunium, also known as eka-actinium or element 121, is a hypothetical chemical element; it has symbol Ubu and atomic number 121. Unbiunium and Ubu are the temporary systematic IUPAC name and symbol respectively, which are used until the element is discovered, confirmed, and a permanent name is decided upon. In the periodic table of the elements, it is expected to be the first of the superactinides, and the third element in the eighth period. It has attracted attention because of some predictions that it may be in the island of stability. It is also likely to be the first of a new g-block of elements.
Unbiquadium, also known as element 124 or eka-uranium, is a hypothetical chemical element; it has placeholder symbol Ubq and atomic number 124. Unbiquadium and Ubq are the temporary IUPAC name and symbol, respectively, until the element is discovered, confirmed, and a permanent name is decided upon. In the periodic table, unbiquadium is expected to be a g-block superactinide and the sixth element in the 8th period. Unbiquadium has attracted attention, as it may lie within the island of stability, leading to longer half-lives, especially for 308Ubq which is predicted to have a magic number of neutrons (184).
Unbihexium, also known as element 126 or eka-plutonium, is a hypothetical chemical element; it has atomic number 126 and placeholder symbol Ubh. Unbihexium and Ubh are the temporary IUPAC name and symbol, respectively, until the element is discovered, confirmed, and a permanent name is decided upon. In the periodic table, unbihexium is expected to be a g-block superactinide and the eighth element in the 8th period. Unbihexium has attracted attention among nuclear physicists, especially in early predictions targeting properties of superheavy elements, for 126 may be a magic number of protons near the center of an island of stability, leading to longer half-lives, especially for 310Ubh or 354Ubh which may also have magic numbers of neutrons.