Darmstadtium

Darmstadtium is a synthetic chemical element with symbol Ds and atomic number 110. It is an extremely radioactive synthetic element. The most stable known isotope, darmstadtium-281, has a half-life of approximately 10 seconds.[6] Darmstadtium was first created in 1994 by the GSI Helmholtz Centre for Heavy Ion Research near the city of Darmstadt, Germany, after which it was named.

In the periodic table, it is a d-block transactinide element. It is a member of the 7th period and is placed in the group 10 elements, although no chemical experiments have yet been carried out to confirm that it behaves as the heavier homologue to platinum in group 10 as the eighth member of the 6d series of transition metals. Darmstadtium is calculated to have similar properties to its lighter homologues, nickel, palladium, and platinum.

Darmstadtium,  110Ds
Darmstadtium
Pronunciation/dɑːrmˈʃtɑːtiəm/ (listen)[1] (darm-SHTAH-tee-əm)
Mass number281 (most stable isotope)
Darmstadtium in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
Pt

Ds

(Uhq)
meitneriumdarmstadtiumroentgenium
Atomic number (Z)110
Groupgroup 10
Periodperiod 7
Blockd-block
Element category  unknown chemical properties, but probably a transition metal
Electron configuration[Rn] 5f14 6d8 7s2 (predicted)[2]
Electrons per shell
2, 8, 18, 32, 32, 16, 2 (predicted)[2]
Physical properties
Phase at STPunknown phase (predicted)[3]
Density (near r.t.)34.8 g/cm3 (predicted)[2]
Atomic properties
Oxidation states(0), (+2), (+4), (+6), (+8) (predicted)[2][4]
Ionization energies
  • 1st: 960 kJ/mol
  • 2nd: 1890 kJ/mol
  • 3rd: 3030 kJ/mol
  • (more) (all estimated)[2]
Atomic radiusempirical: 132 pm (predicted)[2][4]
Covalent radius128 pm (estimated)[5]
Other properties
Natural occurrencesynthetic
Crystal structurebody-centered cubic (bcc)
Body-centered cubic crystal structure for darmstadtium

(predicted)[3]
CAS Number54083-77-1
History
Namingafter Darmstadt, Germany, where it was discovered
DiscoveryGesellschaft für Schwerionenforschung (1994)
Main isotopes of darmstadtium
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
279Ds syn 0.2 s 10% α 275Hs
90% SF
281Ds syn 14 s 94% SF
6% α 277Hs

History

Luisenplatz
The city center of Darmstadt, the namesake of darmstadtium

Discovery

Darmstadtium was first created on November 9, 1994, at the Institute for Heavy Ion Research (Gesellschaft für Schwerionenforschung, GSI) in Darmstadt, Germany, by Peter Armbruster and Gottfried Münzenberg, under the direction of Sigurd Hofmann. The team bombarded a lead-208 target with accelerated nuclei of nickel-62 in a heavy ion accelerator and detected a single atom of the isotope darmstadtium-269:[7]

208
82
Pb + 62
28
Ni → 269
110
Ds + 1
0
n

In the same series of experiments, the same team also carried out the reaction using heavier nickel-64 ions. During two runs, 9 atoms of 271Ds were convincingly detected by correlation with known daughter decay properties:[8]

208
82
Pb + 64
28
Ni → 271
110
Ds + 1
0
n

Prior to this, there had been failed synthesis attempts in 1986–7 at the Joint Institute for Nuclear Research in Dubna (then in the Soviet Union) and in 1990 at the GSI; a 1995 attempt at the Lawrence Berkeley National Laboratory resulted in signs suggesting but not pointing conclusively at the discovery of a new isotope 267Ds formed in the bombardment of 209Bi with 59Co, and a similarly inconclusive 1994 attempt at the JINR showed signs of 273Ds being produced from 244Pu and 34S. Each team proposed its own name for element 110: the American team proposed hahnium after Otto Hahn in an attempt to resolve the situation on element 105 (which they had long been suggesting this name for), the Russian team proposed becquerelium after Henri Becquerel, and the German team proposed darmstadtium after Darmstadt, the location of their institute.[9] The IUPAC/IUPAP Joint Working Party (JWP) recognised the GSI team as discoverers in their 2001 report, giving them the right to suggest a name for the element.[10]

Naming

Darmstadtium official naming ceremony
Ceremony conducted at the GSI for the official naming of darmstadtium on 2 December 2003

Using Mendeleev's nomenclature for unnamed and undiscovered elements, darmstadtium should be known as eka-platinum. In 1979, IUPAC published recommendations according to which the element was to be called ununnilium (with the corresponding symbol of Uun),[11] 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 called it "element 110", with the symbol of E110, (110) or even simply 110.[2]

In 1996, the Russian team proposed the name becquerelium after Henri Becquerel.[12] The American team in 1997 proposed the name hahnium[13] after Otto Hahn (previously this name had been used for element 105).

The name darmstadtium (Ds) was suggested by the GSI team in honor of the city of Darmstadt, where the element was discovered.[14][15] The GSI team originally also considered naming the element wixhausium, after the suburb of Darmstadt known as Wixhausen where the element was discovered, but eventually decided on darmstadtium.[16] Policium had also been proposed as a joke due to the emergency telephone number in Germany being 1-1-0. The new name darmstadtium was officially recommended by IUPAC on August 16, 2003.[14]

Isotopes

For a detailed list of information on the discovery of each individual darmstadtium isotope, see isotopes of darmstadtium.

Darmstadtium 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. Nine different isotopes of darmstadtium have been reported with atomic masses 267, 269–271, 273, 277, and 279–281, although darmstadtium-267 and darmstadtium-280 are unconfirmed. Two darmstadtium isotopes, darmstadtium-270 and darmstadtium-271, have known metastable states. Most of these decay predominantly through alpha decay, but some undergo spontaneous fission.[17]

Stability and half-lives

All darmstadtium isotopes are extremely unstable and radioactive; in general, the heavier isotopes are more stable than the lighter. The most stable known darmstadtium isotope, 281Ds, is also the heaviest known darmstadtium isotope; it has a half-life of 11 seconds. The isotope 279Ds has a half-life of 0.18 seconds respectively. The remaining six isotopes and two metastable states have half-lives between 1 microsecond and 70 milliseconds.[17] Some unknown darmstadtium isotopes may have longer half-lives, however.[18]

List of darmstadtium isotopes
Isotope
Half-life
[17][19]
Decay
mode[17][19]
Discovery
year
Reaction
267Ds ? 2.8 μs α 1994 209Bi(59Co,n)[20]
269Ds 179 μs α 1994 208Pb(62Ni,n)[7]
270Ds 100 μs α, SF 2000 207Pb(64Ni,n)[21]
270mDs 6.0 ms α, IT 2000 207Pb(64Ni,n)[21]
271Ds 1.63 ms α 1994 208Pb(64Ni,n)[8]
271mDs 69 ms α 1994 208Pb(64Ni,n)[8]
273Ds 170 μs α 1996 244Pu(34S,5n)[22]
277Ds 3.5 ms α 2010 285Fl(—,2α)[23][24]
279Ds 0.18 s SF, α 2002 291Lv(—,3α)[25]
280Ds 6.7 ms SF 2014 292Lv(—,3α)[26][27][28]
281Ds 9.6 s SF, α 1999 289Fl(—,2α)[6]

Theoretical calculation in a quantum tunneling model reproduces the experimental alpha decay half-life data for the known darmstadtium isotopes.[29][30] It also predicts that the undiscovered isotope 294Ds, which has a magic number of neutrons (184),[2] would have an alpha decay half-life on the order of 311 years; exactly the same approach predicts a ~3500-year alpha half-life for the non-magic 293Ds isotope, however.[18][31]

Predicted properties

Chemical

Darmstadtium is the eighth member of the 6d series of transition metals. Since copernicium (element 112) has been shown to be a group 12 metal, it is expected that all the elements from 104 to 111 would continue a fourth transition metal series, with darmstadtium as part of the platinum group metals[15] and a noble metal.[2] Calculations on its ionization potentials and atomic and ionic radii are similar to that of its lighter homologue platinum, thus implying that darmstadtium's basic properties will resemble those of the other group 10 elements, nickel, palladium, and platinum.[2]

Prediction of the probable chemical properties of darmstadtium has not received much attention recently. Darmstadtium is expected to be a noble metal. Based on the most stable oxidation states of the lighter group 10 elements, the most stable oxidation states of darmstadtium are predicted to be the +6, +4, and +2 states; however, the neutral state is predicted to be the most stable in aqueous solutions. In comparison, only palladium and platinum are known to show the maximum oxidation state in the group, +6, while the most stable states are +4 and +2 for both nickel and palladium. 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.[2] Darmstadtium hexafluoride (DsF6) is predicted to have very similar properties to its lighter homologue platinum hexafluoride (PtF6), having very similar electronic structures and ionization potentials.[2][32][33] It is also expected to have the same octahedral molecular geometry as PtF6.[34] Other predicted darmstadtium compounds are darmstadtium carbide (DsC) and darmstadtium tetrachloride (DsCl4), both of which are expected to behave like their lighter homologues.[34] Unlike platinum, which preferentially forms a cyanide complex in its +2 oxidation state, Pt(CN)2, darmstadtium is expected to preferentially remain in its neutral state and form Ds(CN)2−
2
instead, forming a strong Ds–C bond with some multiple bond character.[35]

Physical and atomic

Darmstadtium is expected to be a solid under normal conditions and to crystallize in the body-centered cubic structure, unlike its lighter congeners which crystallize in the face-centered cubic structure, because it is expected to have different electron charge densities from them.[3] It should be a very heavy metal with a density of around 34.8 g/cm3. In comparison, the densest known element that has had its density measured, osmium, has a density of only 22.61 g/cm3.[2] This results from darmstadtium's high atomic weight, the lanthanide and actinide contractions, and relativistic effects, although production of enough darmstadtium to measure this quantity would be impractical, and the sample would quickly decay.[2]

The outer electron configuration of darmstadtium is calculated to be 6d87s2, which obeys the Aufbau principle and does not follow platinum's outer electron configuration of 5d96s1. This is due to the relativistic stabilization of the 7s2 electron pair over the whole seventh period, so that none of the elements from 104 to 112 are expected to have electron configurations violating the Aufbau principle. The atomic radius of darmstadtium is expected to be around 132 pm.[2]

Experimental chemistry

Unambiguous determination of the chemical characteristics of darmstadtium has yet to have been established[36] due to the short half-lives of darmstadtium isotopes and a limited number of likely volatile compounds that could be studied on a very small scale. One of the few darmstadtium compounds that are likely to be sufficiently volatile is darmstadtium hexafluoride (DsF
6
), as its lighter homologue platinum hexafluoride (PtF
6
) is volatile above 60 °C and therefore the analogous compound of darmstadtium might also be sufficiently volatile;[15] a volatile octafluoride (DsF
8
) might also be possible.[2] 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.[15] Even though the half-life of 281Ds, the most stable confirmed darmstadtium isotope, is 11 seconds, long enough to perform chemical studies, another obstacle is the need to increase the rate of production of darmstadtium 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 darmstadtium isotopes and have automated systems experiment on the gas-phase and solution chemistry of darmstadtium, 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 darmstadtium has not received as much attention as that of the heavier elements from copernicium to livermorium.[2][36][37]

The more neutron-rich darmstadtium isotopes are the most stable[17] and are thus more promising for chemical studies;[2][15] however, they can only be produced indirectly from the alpha decay of heavier elements.[6][23][25] and indirect synthesis methods are not as favourable for chemical studies as direct synthesis methods.[2] The more neutron-rich isotopes 276Ds and 277Ds might be produced directly in the reaction between thorium-232 and calcium-48, but the yield is expected to be low.[2][38][39] Furthermore, this reaction has already been tested without success,[38] and more recent experiments that have successfully synthesized 277Ds using indirect methods show that it has a short half-life of 3.5 ms, not long enough to perform chemical studies.[24][23] The only known darmstadtium isotope with a half-life long enough for chemical research is 281Ds, which would have to be produced as the granddaughter of 289Fl.[40]

See also

References

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External links

Darmstadt

Darmstadt (German pronunciation: [ˈdaɐ̯mʃtat] (listen)) is a city in the state of Hesse in Germany, located in the southern part of the Rhine-Main-Area (Frankfurt Metropolitan Region). Darmstadt had a population of around 157,437 at the end of 2016. The Darmstadt Larger Urban Zone has 430,993 inhabitants.Darmstadt holds the official title "City of Science" (German: Wissenschaftsstadt) as it is a major centre of scientific institutions, universities, and high-technology companies. The European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) and the European Space Operations Centre (ESOC) are located in Darmstadt, as well as GSI Centre for Heavy Ion Research, where several chemical elements such as bohrium (1981), meitnerium (1982), hassium (1984), darmstadtium (1994), roentgenium (1994), and copernicium (1996) were discovered. The existence of the following elements were also confirmed at GSI Centre for Heavy Ion Research: nihonium (2012), flerovium (2009), moscovium (2012), livermorium (2010), and tennessine (2012). The Facility for Antiproton and Ion Research (FAIR) is an international accelerator facility under construction. Darmstadt is also the seat of the world's oldest pharmaceutical company, Merck, which is the city's largest employer.

Darmstadt was formerly the capital of a sovereign country, the Grand Duchy of Hesse and its successor, the People's State of Hesse, a federal state of Germany. As the capital of an increasingly prosperous duchy, the city gained some international prominence and remains one of the wealthiest cities in Europe. In the 20th century, industry (especially chemicals), as well as large science and electronics (later information technology) sectors became increasingly important, and are still a major part of the city's economy. It is also home to the football club SV Darmstadt 98.

Extended periodic table

An extended periodic table theorizes about chemical elements beyond those currently known in the periodic table and proven up through oganesson, which completes the seventh period (row) in the periodic table at atomic number (Z) 118.

If further elements with higher atomic numbers than this are discovered, they will be placed in additional periods, laid out (as with the existing periods) to illustrate periodically recurring trends in the properties of the elements concerned. Any additional periods are expected to contain a larger number of elements than the seventh period, as they are calculated to have an additional so-called g-block, containing at least 18 elements with partially filled g-orbitals in each period.An eight-period table containing this block was suggested by Glenn T. Seaborg in 1969. The first element of the g-block may have atomic number 121, and thus would have the systematic name unbiunium. Despite many searches, no elements in this region have been synthesized or discovered in nature.According to the orbital approximation in quantum mechanical descriptions of atomic structure, the g-block would correspond to elements with partially filled g-orbitals, but spin-orbit coupling effects reduce the validity of the orbital approximation substantially for elements of high atomic number. While Seaborg's version of the extended period had the heavier elements following the pattern set by lighter elements, as it did not take into account relativistic effects, models that take relativistic effects into account do not. Pekka Pyykkö and Burkhard Fricke used computer modeling to calculate the positions of elements up to Z = 172, and found that several were displaced from the Madelung rule. As a result of uncertainty and variability in predictions of chemical and physical properties of elements beyond 120, there is currently no consensus on their placement in the extended periodic table.

Elements in this region are likely to be highly unstable with respect to radioactive decay and undergo alpha decay or spontaneous fission with extremely short half-lives, though element 126 is hypothesized to be within an island of stability that is resistant to fission but not to alpha decay. Other islands of stability beyond the known elements may also be possible, including one theorized around element 164, though the extent of stabilizing effects from closed nuclear shells is uncertain. It is not clear how many elements beyond the expected island of stability are physically possible, whether period 8 is complete, or if there is a period 9. The International Union of Pure and Applied Chemistry (IUPAC) defines an element to exist if its lifetime is longer than 10−14 seconds, which is the time it takes for the nucleus to form an electron cloud.As early as 1940, it was noted that a simplistic interpretation of the relativistic Dirac equation runs into problems with electron orbitals at Z > 1/α ≈ 137, suggesting that neutral atoms cannot exist beyond element 137, and that a periodic table of elements based on electron orbitals therefore breaks down at this point. On the other hand, a more rigorous analysis calculates the analogous limit to be Z ≈ 173 where the 1s subshell dives into the Dirac sea, and that it is instead not neutral atoms that cannot exist beyond element 173, but bare nuclei, thus posing no obstacle to the further extension of the periodic system. Atoms beyond this critical atomic number are called supercritical atoms.

Gottfried Münzenberg

Gottfried Münzenberg (born 17 March 1940 in Nordhausen, Province of Saxony) is a German physicist.

He studied physics at Justus-Liebig-Universität in Giessen and Leopold-Franzens-Universität Innsbruck and completed his studies with a Ph.D. at the University of Giessen, Germany, in 1971. In 1976 he moved to the department of nuclear chemistry at GSI in Darmstadt, Germany, which was headed by Peter Armbruster. He played a leading role in the construction of SHIP, the 'Separator of Heavy Ion Reaction Products'. He was the driving force in the discovery of the cold heavy ion fusion and the discovery of the elements bohrium (Bh Z=107), hassium (Hs Z=108), meitnerium (Mt Z=109), darmstadtium (Ds Z=110), roentgenium (Rg Z=111) and copernicium (Cn Z=112). In 1984 he became head of the new GSI project, the fragment separator, a project which opened new research topics, such as interactions of relativistic heavy ions with matter, production and separation of exotic nuclear beams and structure of exotic nuclei. He directed the Nuclear Structure and Nuclear Chemistry department of the GSI and was professor of physics at the University of Mainz until he retired in March 2005.

Gottfried Münzenberg was born into a family of Protestant ministers (father Pastor Heinz and mother Helene Münzenberg). All his life he is deeply concerned about the philosophical and theological implications of physics.

Among the rewards he received should be mentioned the Röntgen-Prize of the University of Giessen in 1983 and (together with Sigurd Hofmann) the Otto-Hahn-Prize of the city of Frankfurt/Main in 1996.

Group 10 element

Group 10, numbered by current IUPAC style, is the group of chemical elements in the periodic table that consists of nickel (Ni), palladium (Pd), platinum (Pt), and perhaps also the chemically uncharacterized darmstadtium (Ds). All are d-block transition metals. All known isotopes of darmstadtium are radioactive with short half-lives, and are not known to occur in nature; only minute quantities have been synthesized in laboratories.

Like other groups, the members of this group show patterns in electron configuration, especially in the outermost shells, although for this group they are particularly weak, with palladium being an exceptional case. The relativistic stabilization of the 7s orbital is the explanation to the predicted electron configuration of darmstadtium, which, unusually for this group, conforms to that predicted by the Aufbau principle.

Inorganic compounds by element

This is a list of common inorganic and organometallic compounds of each element. Compounds are listed alphabetically by their chemical element name rather than by symbol, as in list of inorganic compounds.

Isotopes of darmstadtium

Darmstadtium (110Ds) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 269Ds in 1994. There are 9 known radioisotopes from 267Ds to 281Ds (with many gaps) and 2 or 3 known isomers. The longest-lived isotope is 281Ds with a half-life of 9.6 seconds.

Isotopes of hassium

Hassium (108Hs) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 265Hs in 1984. There are 12 known isotopes from 263Hs to 277Hs and 1–4 isomers. The longest-lived isotope is 270Hs with a half-life of 10 seconds.

List of chemical elements naming controversies

The currently accepted names and symbols of the chemical elements are determined by the International Union of Pure and Applied Chemistry (IUPAC), usually following recommendations by the recognized discoverers of each element. However the names of several elements have been the subject of controversies until IUPAC established an official name. In most cases the controversy was due to a priority dispute as to who first found conclusive evidence for the existence of an element, or as to what evidence was in fact conclusive.

List of radioactive isotopes by half-life

This is a list of radioactive isotopes ordered by half-life from shortest to longest.

Major actinide

Major actinides is a term used in the nuclear power industry that refers to the plutonium and uranium present in used nuclear fuel, as opposed to the minor actinides neptunium, americium, curium, berkelium, and californium.

Meitnerium

Meitnerium is a synthetic chemical element with 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 7.6 seconds, although the unconfirmed meitnerium-282 may have a longer half-life of 67 seconds. The GSI Helmholtz Centre for Heavy Ion Research near Darmstadt, Germany, first created this element in 1982. It is named after Lise Meitner.

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 similar properties to its lighter homologues, cobalt, rhodium, and iridium.

Minor actinide

The minor actinides are the actinide elements in used nuclear fuel other than uranium and plutonium, which are termed the major actinides. The minor actinides include neptunium (element 93), americium (element 95), curium (element 96), berkelium (element 97), californium (element 98), einsteinium (element 99), and fermium (element 100). The most important isotopes in spent nuclear fuel are neptunium-237, americium-241, americium-243, curium-242 through -248, and californium-249 through -252.

Plutonium and the minor actinides will be responsible for the bulk of the radiotoxicity and heat generation of used nuclear fuel in the medium term (300 to 20,000 years in the future).The plutonium from a power reactor tends to have a greater amount of Pu-241 than the plutonium generated by the lower burnup operations designed to create weapons-grade plutonium. Because the reactor-grade plutonium contains so much Pu-241 the presence of americium-241 makes the plutonium less suitable for making a nuclear weapon. The ingrowth of americium in plutonium is one of the methods for identifying the origin of an unknown sample of plutonium and the time since it was last separated chemically from the americium.

Americium is commonly used in industry as both an alpha particle and as a low photon energy gamma radiation source. For instance it is used in many smoke detectors. Americium can be formed by neutron capture of Pu-239 and Pu-240 forming Pu-241 which then beta decays to Am-241. In general, as the energy of the neutrons increases, the ratio of the fission cross section to the neutron capture cross section changes in favour of fission. Hence if MOX is used in a thermal reactor such as a boiling water reactor (BWR) or pressurized water reactor (PWR) then more americium can be expected in the used fuel than that from a fast neutron reactor.Some of the minor actinides have been found in fallout from bomb tests. See Actinides in the environment for details.

Peter Armbruster

Peter Armbruster (born 25 July 1931 in Dachau, Bavaria) is a physicist at the Gesellschaft für Schwerionenforschung (GSI) facility in Darmstadt, Germany, and is credited with co-discovering elements 107 (bohrium), 108 (hassium), 109 (meitnerium), 110 (darmstadtium), 111 (roentgenium), and 112 (copernicium) with research partner Gottfried Münzenberg.

He studied physics at the Technical University of Stuttgart and Munich, and obtained his Ph.D. in 1961 under Heinz Maier-Leibnitz, Technical University of Munich. His major research fields are fission, interaction of heavy ions in matter and atomic physics with fission product beams at the Research Centre of Jülich (1965 to 1970). He was Senior Scientist at the Gesellschaft für Schwerionenforschung Darmstadt, GSI, from 1971 to 1996. From 1989 to 1992 he was research Director of the European Institut Laue-Langevin (ILL), Grenoble. Since 1996 he has been involved in a project on incineration of nuclear waste by spallation and fission reactions.

He was affiliated as professor to the University of Cologne (1968) and the Darmstadt University of Technology since 1984.

He has received many awards for his work, including the Max-Born Medal awarded by the Institute of Physics London and the Deutsche Physikalische Gesellschaft in 1988, and the Stern-Gerlach Medal awarded by the Deutsche Physikalische Gesellschaft in 1997. The American Chemical Society honoured Peter Armbruster 1997 as one of few non-Americans with the 'Nuclear Chemistry Award'.

Roentgenium

Roentgenium is a chemical element with symbol Rg and atomic number 111. It is an extremely radioactive synthetic element that can be created in a laboratory but is not found in nature. The most stable known isotope, roentgenium-282, has a half-life of 100 seconds, although the unconfirmed roentgenium-286 may have a longer half-life of about 10.7 minutes. Roentgenium was first created in 1994 by the GSI Helmholtz Centre for Heavy Ion Research near Darmstadt, Germany. It is named after the physicist Wilhelm Röntgen (also spelled Roentgen), who discovered X-rays.

In the periodic table, it is a d-block transactinide element. It is a member of the 7th period and is placed in the group 11 elements, although no chemical experiments have been carried out to confirm that it behaves as the heavier homologue to gold in group 11 as the ninth member of the 6d series of transition metals. Roentgenium is calculated to have similar properties to its lighter homologues, copper, silver, and gold, although it may show some differences from them.

Seaborgium

Seaborgium is a synthetic chemical element with 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 isotope, 269Sg, has a half-life of approximately 14 minutes.In the periodic table of the elements, it is a d-block transactinide element. It is a member of the 7th period and belongs to the group 6 elements as the fourth member of the 6d series of transition metals. Chemistry experiments have confirmed that seaborgium behaves as the heavier homologue to tungsten in group 6. The chemical properties of seaborgium are characterized only partly, but they compare well with the chemistry of the other group 6 elements.

In 1974, a few atoms of seaborgium were produced in laboratories in the Soviet Union and in the United States. The priority of the discovery and therefore the naming of the element was disputed between Soviet and American scientists, and it was not until 1997 that International Union of Pure and Applied Chemistry (IUPAC) established seaborgium as the official name for the element. It is one of only two elements named after a living person at the time of naming, the other being oganesson, element 118.

Synthetic element

In chemistry, a synthetic element is a chemical element that does not occur naturally on Earth, and can only be created artificially. So far, 24 synthetic elements have been created (those with atomic numbers 95–118). All are unstable, decaying with half-lives ranging from 15.6 million years to a few hundred microseconds.

Seven other elements were first created artificially and thus considered synthetic, but later discovered to exist naturally (in trace quantities) as well; among them plutonium—first synthesized in 1940—the one best known to laypeople, because of its use in atomic bombs and nuclear reactors.

Transactinide element

In chemistry, transactinide elements (also transactinides, superheavy elements, or super-heavy elements) are the chemical elements with atomic numbers from 104 to 120. Their atomic numbers are immediately greater than those of the actinides, the heaviest of which is lawrencium (atomic number 103).

Glenn T. Seaborg first proposed the actinide concept, which led to the acceptance of the actinide series. He also proposed the transactinide series ranging from element 104 to 121 and the superactinide series approximately spanning elements 122 to 153. The transactinide seaborgium was named in his honor.By definition, transactinide elements are also transuranic elements, i.e. have an atomic number greater than uranium (92).

The transactinide elements all have electrons in the 6d subshell in their ground state. Except for rutherfordium and dubnium, even the longest-lasting isotopes of transactinide elements have extremely short half-lives of minutes or less. The element naming controversy involved the first five or six transactinide elements. These elements thus used systematic names for many years after their discovery had been confirmed. (Usually the systematic names are replaced with permanent names proposed by the discoverers relatively shortly after a discovery has been confirmed.)

Transactinides are radioactive and have only been obtained synthetically in laboratories. None of these elements have ever been collected in a macroscopic sample. Transactinide elements are all named after physicists and chemists or important locations involved in the synthesis of the elements.

IUPAC defines an element to exist if its lifetime is longer than 10−14 seconds, which is the time it takes for the nucleus to form an electron cloud.

Transuranium element

The transuranium elements (also known as transuranic elements) are the chemical elements with atomic numbers greater than 92, which is the atomic number of uranium. All of these elements are unstable and decay radioactively into other elements.

Victor Ninov

Victor Ninov (Bulgarian: Виктор Нинов, born 1959) is a former researcher in the nuclear chemistry group at Lawrence Berkeley National Laboratory (LBNL) who was alleged to have fabricated the evidence used to claim the creation of elements 118 and 116. These elements were later genuinely discovered by a Russian-American team at the Joint Institute for Nuclear Research in Dubna, Russia and named oganesson and livermorium respectively.Ninov was trained at the Gesellschaft für Schwerionenforschung (GSI) in Germany. His hiring by the LBNL from GSI had been considered a coup: he had been involved in the discovery of darmstadtium, roentgenium, and copernicium (elements 110, 111, and 112) and was considered one of the leading experts at using the complex types of software needed to detect the decay chain of unstable transuranium elements.

An internal committee at the lab concluded that Ninov was the only person in the large project to translate the raw computer results into human-readable results and had used this opportunity to inject false data. Re-examination of the data determined that the raw data contained some factual decay chains of elements 110 and 112, but one false decay chain had also been injected into the data for each element.Reports on the Ninov affair were released around the same time that the final report on the Schön affair, another major incident of fraud in physics. As a result, the American Physical Society adopted more stringent ethical guidelines, especially those regulating the conduct of co-authors.

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