Page 2 Contents: #43 Tc, #85 At, #91 Pa, #104 Unq=Rf, #105 Unp=Db, #106 Unh=Sg, #107 Uns=Bh, #108 Uno=Hs, #109 Une=Mt, #110 Uun=Ds, #111 Uuu=Rg, #112 Uub, #113 Uut, #114 Uuq, #115 Uup, #116 Uuh, #117 Uus, #118 Uuo
The German Otto Hahn (b1879, d1968) was a good student who handicapped himself by skipping physics and mathematics lectures to spend more time doing chemistry laboratory work. Interested in an industry job requiring English, he spent time in England with Sir William Ramsay. Assigned to separate Radium from Barium salts, he became acquainted with handling and measuring radioactive elements. Working with Ramsay, he discovered a
new element which he named Radiothorium. (It turned out to actually be a new isotope, 228Th, of the previously known element Thorium.) He won an appointment to study with Ernest Rutherford at McGill University where he learned state-of-the-art methods of working with radioactive materials and found two additional
elements by their unique radiation intensities and half-lives. (These turned out to actually be isotopes 212Po and 227Th of two previously know elements.) He then returned to Berlin to set up a radiation laboratory in Emil Fischer´s Chemical Institute and found another
element (later found to be a mixture of 228Ra and 228Ac).
A very shy Austrian, Lise Meitner (b1878, d1968), arrived in Berlin with exception permission from Max Planck, Professor of Theoretical Physics at the University, to audit his lectures. While women were expected to marry and tend the nursery and kitchen, Meitner had achieved a Doctorate in physics and post-graduate experience studying radioactivity. Soon Heinrich Rubens, Professor of Experimental Physics at the University, arranged for Meitner to do radiation work with Otto Hahn at the Chemical Institute. They chose to survey beta emitting elements and discovered additional isotopes. While women were not permitted in the Chemical Institute, Meitner could set foot only in the basement woodshop accessed by its own exterior door. When a toilet was needed, she could used a nearby restaurant´s facilities. A year later when women were legally admitted to universities, a ladies´ room was installed but Lise remained invisible. Their collaboration proved productive with Hahn doing tedious chemical separations and Meitner doing experimental measurements and calculations and speculating about the physics. (1910 photo at right→ shows Hahn and Meitner at Fischer Institute with electroscope radiation detectors on table.) During World War I they began a search for the parent substance that produces Actinium. Hahn spent nearly full time at the front with the gas-warfare corps. Rarely introspective, Hahn later wrote:
our minds were so numbed that we no longer had any scruples about the whole thing (poison gas warfare). Meitner served as an X-ray nurse-technician until the military stalemate provided little for her to do. Returning to Berlin, Meitner working alone measured silica fractions from pitchblende expected to contain the eka-Tantalum originally predicted by Mendeleev. Over five years Meitner detected a build up of radiation from the expected element, eliminated other possible causes of the radiation, and measured its half-life. In 1917 while Hahn was away at the front, Emile Fischer appointed Meitner head of her own section, in effect dividing the Laboratorium Hahn-Meitner in two, and increased Meitner´s pay equivalent to Hahn´s salary. In March 1918 Meitner submitted a joint paper with Hahn listed as the senior investigator describing a long-lived element that was the parent of Actinium. They proposed the name Protoactinium which eventually was shortened to Protactinium (Pa = #91). Protos (Greek) meaning prior was combined with the name of the daughter element, Actinium.
After World War I Meitner continued working with Hahn. Their German team joined by chemist Fritz Strassmann competed with an Italian team led by Enrico Fermi and a French team led by Marie Curie to artificially produce new elements heavier than Uranium by addition of neutrons. Born a Jew, Meitner had withdrawn Jewish registration and was baptized a Protestant in 1908. But mid-experiment Meitner was forced to secretly flee Germany in 1938 to avoid internment for her Jewish ancestry. She continued to obtained team results by letter. Meitner was joined on the Swedish coast for Christmas by her nephew, Otto Frisch. She shared her long held concern over discrepancies between product Strassmann seemed to identify and her mass-energy calculations for the reaction. In discussions they held out in the snow, Meitner gradually realized that contrary to the hoped for fusion to make larger atoms, Uranium atoms struck with neutrons were splitting (!) into two nearly equal halves. She relayed that explanation to Hahn and Frisch told Niels Bohr. Bohr carried the news to a meeting of physicists in New York. Hahn claimed he proposed and discovered fission and was awarded the 1944 Nobel Prize for Chemistry for the discovery. Meitner never worked with Hahn again although they remained close friends.
Earlier attempts to find element #43 were believed to had failed. In 1939 Emilio Segrè and Carlo Perrier of Palermo obtained from E.O. Lawrence of Berkeley a sample of Molybdenum which had been bombarded with deuterons in Lawrence´s cyclotron for several months. Segrè and Perrier found radioactivity that did not separate with Niobium, Zirconium or Molybdenum so was not caused by a member of those chemical families. But the radiation could be separated using Manganese and Rhenium as carriers indicating it was the missing member of their chemical family. A stream of hydrogen chloride gas volatilized the radioactive element allowing separation from the carriers. The amount estimated to be 10-10 g was not weighable. Segrè working with C.S. Wu again encountered element #43 among fission products in 1940. After F.A. Paneth suggested in 1947 that the first producer of an artificial element be entitled to name the element, Segrè and Perrier suggest the name Technetium (Tc = #43). Technetos (Greek) means artificial: Technetium was the first element artificially produced.
Successful synthesis of element #43 in Lawrence´s cyclotron suggested the possibility of preparing element #85, eka-Iodine, in a similar manner. Calculations suggested alpha particles with more than 20 MeV would be required. Upon completion of the 60" cyclotron in 1940, Emilio Segrè, R. R. Corson, and K. R. MacKenzie bombarded a water-cooled Bismuth target with 32 Mev Helium ions. They filed off the surface of the Bismuth target and dissolved the filings in concentrated nitric acid. Working with quantities too small to see or weigh, they followed the radiation emitted by the new element. Its properties were similar to the metals Polonium and Bismuth instead of Iodine. It precipitated with hydrogen sulfide in acid, was not precipitated by Silver ions, and could be electroplated on metal surfaces. They called the new element Astatine (At = #85). A-statos (Greek) means not standing or not lasting: Astatine is radioactive and disintegrates by alpha decay with a half life of about 7.5 hours. There is less than 1 mg on earth. -ine denotes Astatine is a member of the halogen family.
In 1921 the International Union of Pure and Applied Chemists (IUPAC) established the Commission on the Nomenclature of Inorganic Chemistry (CNIC). Rules for accepting element names were established in 1938 with revisions in 1957 and 1970. Proposed names for elements #102, #104 and #105 honored famous scientists. However rival claims to discoveries during the "cold war" became a nationalistic dispute. The IUPAC had difficulty establishing which country had priority.In 1976 CNIC recommended systematic numeric names for elements beyond #103 while claims for priority of discovery were being considered. According to this proposal, element #104 should be called Unnilquadium: (Latin)
quad= 4, with the ending -ium denoting a metal. The symbol would be the three letter abbreviation Unq. During 1964, scientists at Dubna in Russia claimed discovery of element #104 and suggested the name Kurchatovium and symbol Ku for the element, in honor of Igor Vasilevich Kurchatov (1903-1960), the late Head of Soviet Nuclear Research. Their experiments involved the collision reactions between Neon ions and Plutonium.
2210Ne + 24294Pu → 261104Rf + 1 10nIn 1969 an American group at Berkeley (California) in the USA reported isotopes of Element #104. The American group claimed that they were unable to reproduce the earlier Russian synthesis from 1964. But they claimed a reaction using high energy collisions of Carbon ions and Californium atoms.
The American group proposed the name Rutherfordium (Rf), in honor of Ernest Rutherford, the New Zealand physicist. Rutherfordium is now the official IUPAC name.Unnilpentium (#105 = Unp) was synthesized by Russian and American workers independently. Proposed names were Nielsbohrium (USSR) and Hahnium (USA). In 1967, Flerov reported element #105 after bombarding Americium ions with Neon ions at the Joint Research Institute, Dubnia, Russia.
2210Ne + 24395Am → 262105Db + 3 10nIn 1970, Ghiorso and others announced their synthesis of element #105 at Berkeley, California by bombarding Californium ions with Nitrogen ions.
157N + 24998Cf → 262105Db + 2 10nElement #105 is now called Dubnium after the location of first production.
Unnilhexium (#106 = Unh) is now called Seaborgium (Sg) after the American chemist. The first report of element #106 came in 1974 from the Soviet Joint Institute for Nuclear Research. 280 MeV Chromium ions from the 310 cm cyclotron were used to strike targets of 206Pb, 207Pb, and 208Pb, in separate runs. Foils exposed to a rotating target disc were used to detect spontaneous fission activities. The foils were etched and examined microscopically to detect the number of fission tracks and the half-life of the fission activity.
1993 experiments at Berkeley finally confirmed the discovery with the collision of Californium atoms with Oxygen ions.
Unnilseptium (#107 = Uns) is now called Bohrium after Niels Bohr, In 1976 Soviet scientists at Dubna announced they had synthesized element #107 by bombarding Bismuth with heavy nuclei of Chromium. Reports say that experiments in 1975 had allowed scientists
to glimpse the new element for 2/1000 s. A rapidly rotating cylinder, coated with a thin layer of bismuth metal, was used as a target. This was bombarded by a stream of Chromium ions fired tangentially.
The existence of element #107 was confirmed by a team in 1981 at the Heavy Ion Research Laboratory at Darmstadt, who created and identified six nuclei of element #107.
Unniloctium (#108 = Uno) is now called Hassium (Latin) for Germany where it was first produced at the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt.
Unnilennium (#109 = Une) is now called Meitnerium after the Austrian physicist Lise Meitner. In August 1982 the first atom of the element Meitnerium with atomic number #109 was detected at GSI in Darmstadt, Germany. The new element was produced by fusing an iron ion and a bismuth atom together in a reaction that produces a neutron. They accelerated the iron ions to a high energy in the heavy ion accelerator, UNILAC.
Ununnilium (#110 = Uun): is now called Darmstadtium (Ds). On 9 November 1994 at 4:39 PM the first atom of the heaviest chemical element with atomic number 110 was detected at GSI in Darmstadt, Germany. The element was the subject of a ten year search by many laboratories. International scientists lead by Sigurd Hofmann (on left) and Peter Armbruster (on right) to made and detected the element: [V.Ninov, F.P.Heβberger, H.Folger, G.Münzenberg, H.J.Schött of GSI; A.G.Popeko, A.V.Yeremin, A.N.Andreyev of Flerov Laboratory, Dubna, Russia; S.Saro, R.Janik of Comenius University, Bratislava, Slovakia, and M.Leino of University of Jyväskylä Jyväskylä, Finland] The element was produced by fusing Nickel and Lead together. This was achieved by accelerating many billion billion Nickel ions to a very specific high velocity in the heavy ion accelerator, UNILAC, at a Lead target.
The single atom of element #110 was produced and immediately evaporated by the energy of the collision, selected by a velocity filter and then captured in a detector system which measured the decay. The energy of the emitted alpha particle served to identify the atom produced.
Unununium (#111 = Uuu) is now called Roentgenium (Rg). It was discovered on 8 December 1994 by S. Hofmann, V. Ninov, F.P. Hessberger, P. Armbruster, H. Folger, G. Münzenberg, and others at GSI in Darmstadt, Germany. This was the second new element created by GSI within a month! Three atoms of Uuu were produced in reactions between Bismuth targets and Nickel projectiles. To achieve this, the Nickel atoms were accelerated to high energies by the heavy ion accelerator, UNILAC, and directed onto a Bismuth target.
Ununbium (#112 = Uub) was discovered on 9 February 1996 at 10:37 PM by S. Hofmann, V. Ninov, F.P. Hessberger, P. Armbruster, H. Folger, G. Münzenberg, and others at their Helmholtzzentrum für Schwerionenforschung (Center for Heavy Ion Research) a part of Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany. The atom was produced by fusing a Zinc atom with a Lead atom. To achieve this, the Zinc atom was accelerated to high energies by the heavy ion accelerator, UNILAC, and directed onto a Lead target.
Thirteen years later, after the International Union of Pure and Applied Chemistry officially acknowledged confirmation of discovery, the GSI team suggested the name Copernicium to honor astronomer Nicolaus Copernicus (b1473, d1543),. The element symbol for element #112 should be Cn (after first proposing Cp). Copernicus proposed a system of circular obits and epicycles which included the Earth orbiting a stationary Sun. Copernicus claimed that system matched observations while avoided imperfections of previous theories, thus paving the way for our modern view of the world.
Ununtrium (#113 = Uut) was formed by the alpha emission from element #115. The lifetime of one of the four atoms produced was 1.2 seconds, very lengthly compared to previously formed super-heavy elements. The chain of alpha decays continued through elements 111, 109, 107 and 105, one of which lasted about 24 hours before it fissioned.
Ununquadium (#114 = Uuq): Only one atom of element #114 was made through a nuclear reaction involving fusing a Calcium ion with a Plutonium atom. The discovery was reported informally in January 1999 following experiments towards the end of December 1998 involving scientists from the Joint Institute for Nuclear Research, Dubna, Russia and the Lawrence Livermore National Laboratory, Berkeley, California. Additional atoms were later produced as decay products of elements #118/116. (But that story continues below...)
Discovery of the elements having atomic numbers 114 and 116 was finally officially recognized as confirmed by the International Union of Pure and Applied Chemistry in June 2011. In December 2011 after approval by the IUPAC, the collaborating discoverers at the Lawrence Livermore National Laboratory-Dubna proposed names. The element 114 is to be Flerovium with symbol Fl to honor the Flerov Laboratory of Nuclear Reactions in Dubna, Russia, where a number of super-heavy elements, including element 114, were made.
Ununpentium (#115 = Uup): Scientists at Lawrence Livermore National Laboratory, in collaboration with researchers from the Joint Institute for Nuclear Research (JINR) in Dubna, Russia announced February 2, 2004, the discovery of element #115 and subsequent alpha decay to element #113. In experiments conducted over a month at the JINR U400 cyclotron between 14 July and 10 August 2003, the scientists observed alpha decay chains that confirm the existence of both element #115 and element #113. The experiments produced four atoms each of the two elements through the fusion reaction of Calcium-48 nuclei hitting an Amercium-243 target atoms coated on a spinning foil of Titanium.
Ununhexium (#116 = Uuh): First production of elements #116 and #118 was claimed in 1999 by an international team working at Lawrence Berkeley National Laboratory, the University of California, and Oregon State University: V. Ninov, K.E. Gregorich, W. Loveland, A. Ghiorso, D.C. Hoffman, D.M. Lee, H. Nitsche, W.J. Swiatecki, U.W. Kirbach, C.A. Laue, J.L. Adams, J.B. Patin, D.A. Shaughnessy, D.A. Strellis, and P.A. Wilk. The experiment was carried out following calculations by Robert Smolanczuk from Soltan Institute for Nuclear Studies, Poland, on the fusion of atomic nuclei. His calculations suggested that it might be possible to make element #118 by fusing Lead with Krypton under carefully controlled conditions. Their data suggested that the element #118 nucleus decayed in less than a millisecond after its formation by emitting an α-particle. This resulted in an isotope of element #116 which was also radioactive and underwent further α-decay to an isotope of element #114:
But these discoveries were not to last. In mid-summer 2001 the Lawrence Berkeley group retracted their claim to have made elements #118 and #116. Their attempts and those of German and Japanese laboratories to reproduce the original results failed. Re-analysis of the original data also failed to find evidence for the claimed products. However researchers from the Lawrence Livermore National Laboratory (across the ridge from Berkeley) in California and the Joint Institute for Nuclear Research in Dubna, Russia, later created element #116 directly. The elements with atomic numbers 114 and 116 the collaboration created were officially recognized in June 2011 by the International Union of Pure and Applied Chemistry. In December 2011, the collaborators at the Lawrence Livermore National Laboratory and Dubna proposed names. The element #116 is to be Livermorium with the symbol Lv to honor Lawrence Livermore National Laboratory in Livermore, Calif.
Ununseptium (#117 = Uus) is the temporary name. The team produced six atoms of the element by smashing together isotopes of Calcium and the radioactive element Berkelium in a particle accelerator about 75 miles north of Moscow on the Volga River at the Joint Institute for Nuclear Research in Dubna. Various aspects of the work were done at the particle accelerator in Dubna; the Lawrence Livermore National Laboratory, Oak Ridge National Laboratory, Vanderbilt University, the University of Nevada, Las Vegas and the Research Institute of Atomic Reactors in Dimitrovgrad, Russia. Berkelium-249 is not an element naturally found on earth, having a half-life of only about a year. Instead a research nuclear reactor at Oak Ridge produced about 20 milligrams of highly purified Berkelium (shown at right→). It was sent it to Russia, where the substance was bombarded for five months late 2009 and early 2010. Five of the six new atoms contained 176 neutrons, while one atom contained 177 neutrons. Isotopes of these new element with 117 protons were identified by observing their characteristic series of decays. Data collected by the team seem to support the island of stability which theorists have long suspected: the newly created elements and still heavier isotopes are more stable and longer-lived than those of lesser charge and mass. Some theories predict this island of stability will center around nuclei with 184 neutrons and either 120 or 126 protons. Elements #116 and #118 were produced and discovered earlier because odd numbered elements are a little less stable and have more complex decay chains.
Ununoctium (#118 = Uuo) was originally thought to be made by accelerating a beam of Krypton ions to an energy of 449 MeV and directing the beam onto targets of Lead. After 11 days, their data indicated three atoms of the new element were made:
But as described above, this was not confirmed. The claim for production of element #118 was withdrawn.
31 January 2006 (published October 2006) researchers from Russia's Joint Institute for Nuclear Research and the Lawrence Livermore National Laboratory in California (Yu. Ts. Oganessian, V. K. Utyonkov, Yu. V. Lobanov, F. Sh. Abdullin, A. N. Polyakov, R. N. Sagaidak, I. V. Shirokovsky, Yu. S. Tsyganov, A. A. Voinov, G. G. Gulbekian, S. L. Bogomolov, B. N. Gikal, A. N. Mezentsev, S. Iliev, V. G. Subbotin, A. M. Sukhov, K. Subotic, V. I. Zagrebaev, G. K. Vostokin, M. G. Itkis, K. J. Moody, J. B. Patin, D. A. Shaughnessy, M. A. Stoyer, N. J. Stoyer, P. A. Wilk, J. M. Kenneally, J. H. Landrum, J. F. Wild, and R. W. Lougheed) announced to Physical Review that they had indirectly detected element 118 produced via collisions of Calcium with Californium atoms. They used two projectile energies corresponding to 297118 compound nucleus excitation energies of E* = 29.2 MeV (±2.5) and 34.4 MeV (±2.3). The total beam irradiation was 4.1x1019 48Ca projectiles.
Element 118 decays into element 116 by α decay. The decay products of three daughter atoms have been observed.
The decay properties of daughter isotopes 290116Uuh and 291116Uuh, and the dependence of their production cross sections on the excitation energies of the compound nucleus, 293116Uuh, have been measured by alternate synthesis of larger amounts by collsions of 245Cm (48Ca, xn) 293-x116. Three similar decay chains consisting of two or three consecutive α decays and terminated by a spontaneous fission with high total kinetic energy of about 230 MeV were observed. The three decay chains originated from the even/even isotope 294118Uuo, Eα = 11.65 MeV (±0.06), Tα = 0.89 ms (+1.07-0.31) which were produced by evaporation of 3 neutrons from the intermediate compound nucleus formed from the 48Ca + 249Cf collsions with a maximum cross section of 0.5 (+1.6-0.3). Within seconds, subsequent α decays (of the odd/even isotope?) continue until the more stable Seaborgium-271, with a half-life of 1.9 min, is reached. This will further alpha decay into Rutherfordium-267, with a half-life of 1.3 hours. There was speculation that element 118 might be named Dubnadium (Dn) after Dubna, Russia where it was created. (But element 105 is already so named.)
|introduction||alchemy||planets||other celestial objects||color||other properties||myths||people||minerals||ore mines||other places|
|to site menu||Introduction to
Development of Periodic Chart
|18th Century vocabulary,
& index of people
|created 31 December 2000, amplified 11 March 2001
latest revision 10 January 2012
|by D Trapp|