Instruct: Given a question, retrieve passages that answer the question.
Query: Who created the element hassium?
Also in 1984, a research team led by Peter Armbruster and Gottfried Münzenberg at the Gesellschaft für Schwerionenforschung (GSI; Institute for Heavy Ion Research) in Darmstadt, Hesse, West Germany, attempted to create element 108. The team bombarded a target of lead with accelerated nuclei of iron. They reported synthesis of 3atoms of 265108.[12]
The previous members of group 8 have relatively high melting points (Fe, 1538°C; Ru, 2334°C; Os, 3033°C). Much like them, hassium is predicted to be a solid at room temperature,[46] although the melting point of hassium has not been precisely calculated. Hassium should crystallize in the hexagonal close-packed structure (c/a=1.59), similarly to its lighter congener osmium.[46] Pure metallic hassium is calculated to have a bulk modulus (resistance to uniform compression) comparable to that of diamond[46][47] (442GPa).[48] Hassium is expected to have a bulk density of 40.7g/cm3, the highest of any of the 118 known elements and nearly twice the density of osmium,[2] the most dense measured element,[49] at 22.61g/cm3.[50] This results from hassium's high atomic weight, the lanthanide and actinide contractions, and relativistic effects, although production of enough hassium to measure this quantity would be impractical, and the sample would quickly decay.[2] Osmium is the densest element of the first 6 periods, and its heavier congener hassium is expected to be the densest element of the first 7 periods.[2][49]
The superheavy elements from hassium to livermorium inclusive are expected to be "partially very noble metals"; chemical investigations of hassium and copernicium have established that they behave like their lighter homologs, the noble osmium and mercury, and preliminary investigations of nihonium and flerovium have suggested but not definitively established noble behavior.
According to Mendeleev's nomenclature for unnamed and undiscovered elements, hassium should be known as eka-osmium. In 1979, IUPAC published recommendations according to which the element was to be called unniloctium (with the corresponding symbol of Uno),[15] 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 108", with the symbol of E108, (108), or even simply 108, or used the proposed name "hassium".[2]
In the periodic table of the elements, it is a d-block transactinide element. Hassium is a member of the 7th period and belongs to the group 8 elements: it is thus the sixth member of the 6d series of transition metals. Chemistry experiments have confirmed that hassium behaves as the heavier homologue to osmium in group 8. The chemical properties of hassium are characterized only partly, but they compare well with the chemistry of the other group 8 elements. In bulk quantities, hassium is expected to be a silvery metal that reacts readily with oxygen in the air, forming a volatile tetroxide.
In 2004 scientists reacted hassium tetroxide and sodium hydroxide to form sodium hassate(VIII), a reaction well known with osmium. This was the first acid-base reaction with a hassium compound, forming sodium hassate(VIII):[68]
In the 1970s Oganessian invented cold fusion, a technique to produce transactinide elements (super-heavy elements). It played a vital role in the discoveries of elements from 104 to 113. From the mid-1970s to the mid-1990s, the partnership of JINR, led by Oganessian, and the GSI Helmholtz Centre for Heavy Ion Research in Germany, led to the discovery of six chemical elements (107 to 112): bohrium, meitnerium, hassium, darmstadtium, roentgenium, and copernicium. 
Temporary symbols assigned to newly or not-yet synthesized elements use 3-letter symbols based on their atomic numbers. For example, "Uno" was the temporary symbol for hassium (element 108) which had the temporary name of "unniloctium".
Group 8 is a group of chemical element in the periodic table. It consists of iron (Fe), ruthenium (Ru), osmium (Os) and hassium (Hs). They are all transition metals. Like other groups, the members of this family show patterns in electron configuration, especially in the outermost shells, resulting in trends in chemical behavior.
Hassium has been observed as decay products of darmstadtium. Darmstadtium currently has eight known isotopes, all of which have been shown to undergo alpha decays to become hassium nuclei, with mass numbers between 263 and 277. Hassium isotopes with mass numbers 266, 273, 275, and 277 to date have only been produced by darmstadtium nuclei decay. Parent darmstadtium nuclei can be themselves decay products of copernicium, flerovium, or livermorium. To date, no other elements have been known to decay to hassium. For example, in 2004, the Dubna team identified hassium-277 as a final product in the decay of livermorium via an alpha decay sequence:
In 2004, the Joint Institute for Nuclear Research conducted a search for natural hassium. This was done underground to avoid interference and false positives from cosmic rays, but no results have been released, strongly implying that no natural hassium was found. The possible extent of primordial hassium on Earth is uncertain; it might now only exist in traces, or could even have completely decayed by now after having caused the radiation damage long ago.[13]
Hahn's death did not stop his public acclamation. Proposals were made at different times, first in 1971 by American chemists, that the newly synthesized element no. 105 should be named hahnium in Hahn's honor; in 1997 the IUPAC (International Union of Pure and Applied Chemistry) named it dubnium, after the Russian research center in Dubna (see element naming controversy). Although element 108 was given the name hassium (after Hesse) by its officially recognized German discoverers in 1992, a 1994 IUPAC committee recommended that it be named hahnium (Hn), in spite of the long-standing convention to give the discoverer the right to suggest a name. This recommendation was not adopted, following protests from the German discoverers, and the name hassium (Hs) was adopted internationally in 1997.
Chemical series information for elements past hassium (except copernicium), is hypothetical and based on periodic trends.
IUPAC adopted unniloctium (Uno) as a temporary, systematic element name.
In 1997 a committee of IUPAC recommended that element 108 be named hassium (Hs), in honor of the German state of Hesse (or Hassia in Latin). This state includes the city of Darmstadt, which is home to the GSI Helmholtz Centre for Heavy Ion Research where several new elements were discovered or confirmed. The element name was accepted internationally.
Various calculations show that hassium should be the heaviest known group 8 element, consistent with the periodic law. Its properties should generally match those expected for a heavier homologue of osmium, with a few deviations arising from relativistic effects.
Hassium 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. Twelve different isotopes have been reported with atomic masses from 263 to 277 (with the exceptions of 272, 274, and 276), three of which, hassium-265, hassium-267, hassium-269, have known metastable states. Most of these decay predominantly through alpha decay, but some also undergo spontaneous fission.[28][37]
Hassium is the sixth member of the 6d series of transition metals and is expected to be much like the platinum group metals.[52] Calculations on its ionization potentials, atomic radius, as well as radii, orbital energies, and ground levels of its ionized states are similar to that of osmium, implying that hassium's properties would resemble those of the other group 8 elements, iron, ruthenium, and osmium.[2][53] Some of these properties were confirmed by gas-phase chemistry experiments.[54][55][56] The group 8 elements portray a wide variety of oxidation states, but ruthenium and osmium readily portray their group oxidation state of +8 (the second-highest known oxidation state for any element, which is very rare for other elements) and this state becomes more stable as the group is descended.[51][57][58] Thus hassium is expected to form a stable +8 state.[55] Analogously to its lighter congeners, hassium is expected to also show other stable lower oxidation states, such as +6, +5, +4, +3, and +2.[13][2][6] Indeed, hassium(IV) is expected to be more stable than hassium(VIII) in aqueous solution.[2]
Hassium is not known to occur naturally on Earth; the half-lives of all its known isotopes are short enough that no primordial hassium would have survived to the present day. This does not rule out the possibility of unknown longer-lived isotopes or nuclear isomers existing, some of which could still exist in trace quantities today if they are long-lived enough. In the early 1960s, it was predicted that long-lived deformed isomers of hassium might occur naturally on Earth in trace quantities. This was theorized in order to explain the extreme radiation damage in some minerals that could not have been caused by any known natural radioisotopes, but could have been caused by superheavy elements.[13]
Hassium (Hs) 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 Hs in 1984. There are 12 known isotopes from Hs to Hs and 1–4 isomers. The longest-lived isotope is Hs with a half-life of 10 seconds.Super-heavy elements such as hassium are produced by bombarding lighter elements in particle accelerators that induce fusion reactions. Whereas most of the isotopes of hassium can be synthesized directly this way, some heavier ones have only been observed as decay products of elements with higher atomic numbers.
With increasing atomic number, the experimental difficulties of producing and identifying a new element increase significantly. In the 1970s and 1980s, resources for new element research at Berkeley were diminishing, but the GSI laboratory at Darmstadt, Germany, under the leadership of Peter Armbruster and with considerable resources, was able to produce and identify elements 107-109 (107, bohrium; 108, hassium and 109, meitnerium). In the early 1990s, the Berkeley and Darmstadt groups made a collaborative attempt to create element 110. Experiments at Berkeley were unsuccessful, but eventually elements 110-112 (110, darmstadtium; 111, roentgenium and 112, copernicium) were identified at the Darmstadt laboratory. Subsequent work at the JINR laboratory at Dubna, led by Yuri Oganessian and a Russian-American team of scientists, was successful in identifying elements 113-118 (113, nihonium; 114, flerovium; 115, moscovium; 116, livermorium; 117, tennessine and 118, oganesson), thereby completing the seventh row of the periodic table of the elements.
The synthesis of element 108 was first attempted in 1978 by a research team led by Yuri Oganessian at the Joint Institute for Nuclear Research (JINR) in Dubna, Moscow Oblast, Russian SFSR, Soviet Union. The team used a reaction that would generate 270108 from radium and calcium. The researchers were uncertain in interpreting result data; the paper did not unambiguously claim discovery.[8] That same year, another team at JINR investigated the possibility of synthesis of element 108 in reactions between lead and iron; they were uncertain in interpreting result data as well, openly suggesting a possibility that element 108 had not been created.[9]
In 2006, it was hypothesized that an isomer of 271Hs might have a half-life of around (2.5±0.5)×108 years, which would explain the observation of alpha particles with energies of around 4.4MeV in some samples of molybdenite and osmiridium.[24] This isomer of 271Hs could be produced from the beta decay of 271Bh and 271Sg, which, being homologous to rhenium and molybdenum respectively, should occur in molybdenite along with rhenium and molybdenum if they occurred in nature. Since hassium is homologous to osmium, it should also occur along with osmium in osmiridium if it occurred in nature. The decay chains of 271Bh and 271Sg are very hypothetical and the predicted half-life of this hypothetical hassium isomer is not long enough for any sufficient quantity to remain on Earth.[24] It is possible that more 271Hs may be deposited on the Earth as the Solar System travels through the spiral arms of the Milky Way, which would also explain excesses of plutonium-239 found on the floors of the Pacific Ocean and the Gulf of Finland, but minerals enriched with 271Hs are predicted to also have excesses of uranium-235 and lead-207, and would have different proportions of elements that are formed during spontaneous fission, such as krypton, zirconium, and xenon. Thus, the occurrence of hassium in nature in minerals such as molybdenite and osmiride is theoretically possible, but highly unlikely.[24]
The synthetic element hassium, number 108 on the periodic table, was named after the state of Hesse in 1997, following a proposal of 1992.
Despite the fact that the selection of a volatile hassium compound (hassium tetroxide) for gas-phase chemical studies was clear from the beginning,[2][57] the chemical characterization of hassium was considered a difficult task for a long time.[57] Although hassium isotopes were first synthesized in 1984, it was not until 1996 that a hassium isotope long-lived enough to allow chemical studies to be performed was synthesized. Unfortunately, this hassium isotope, 269Hs, was then synthesized indirectly from the decay of 277Cn;[57] not only are indirect synthesis methods not favourable for chemical studies,[2] but also the reaction that produced the isotope 277Cn had a low yield (its cross-section was only 1pb),[57] and thus did not provide enough hassium atoms for a chemical investigation.[52] The direct synthesis of 269Hs and 270Hs in the reaction 248Cm(26Mg,xn)274−xHs (x=4 or 5) appeared more promising, as the cross-section for this reaction was somewhat larger, at 7pb.[2][57] This yield was still around ten times lower than that for the reaction used for the chemical characterization of bohrium.[57] New techniques for irradiation, separation, and detection had to be introduced before hassium could be successfully characterized chemically as a typical member of group 8 in early 2001.[2][57]
The name hassium was proposed by Peter Armbruster and his colleagues, the officially recognised German discoverers, in September 1992. It is derived from the Latin name Hassia for the German state of Hesse where the institute is located.[13][16] In 1994, IUPAC Commission on Nomenclature of Inorganic Chemistry recommended that element 108 be named hahnium (Hn) after the German physicist Otto Hahn so that elements named after Hahn and Lise Meitner (meitnerium) would be next to each other, honoring their joint discovery of nuclear fission.[17] This was because they felt that Hesse did not merit an element being named after it.[13] GSI protested saying that this contradicted the long-standing convention to give the discoverer the right to suggest a name;[18] the American Chemical Society supported the GSI.[13] IUPAC relented and the name hassium (Hs) was adopted internationally in 1997.[19]