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.

Roentgenium,  111Rg
Roentgenium
Pronunciation
  • /rʌntˈɡɛniəm/ (listen)
    (runt-GEN-ee-əm)
  • /rɛntˈɡɛniəm/
    (rent-GEN-ee-əm)
Appearancesilvery (predicted)[1]
Mass number282 (most stable isotope) (unconfirmed: 286)
Roentgenium 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
Au

Rg

(Uhp)
darmstadtiumroentgeniumcopernicium
Atomic number (Z)111
Groupgroup 11
Periodperiod 7
Blockd-block
Element category  unknown chemical properties, but probably a transition metal
Electron configuration[Rn] 5f14 6d9 7s2 (predicted)[1][2]
Electrons per shell
2, 8, 18, 32, 32, 17, 2 (predicted)
Physical properties
Phase at STPunknown phase (predicted)[3]
Density (near r.t.)28.7 g/cm3 (predicted)[2]
Atomic properties
Oxidation states(−1), (+1), (+3), (+5) (predicted)[2][4]
Ionization energies
  • 1st: 1020 kJ/mol
  • 2nd: 2070 kJ/mol
  • 3rd: 3080 kJ/mol
  • (more) (all estimated)[2]
Atomic radiusempirical: 138 pm (predicted)[2][4]
Covalent radius121 pm (estimated)[5]
Other properties
Natural occurrencesynthetic
Crystal structurebody-centered cubic (bcc)
Body-centered cubic crystal structure for roentgenium

(predicted)[3]
CAS Number54386-24-2
History
Namingafter Wilhelm Röntgen
DiscoveryGesellschaft für Schwerionenforschung (1994)
Main isotopes of roentgenium
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
272Rg syn 2 ms α 268Mt
274Rg syn 12 ms α 272Mt
278Rg syn 4 ms α 274Mt
279Rg syn 0.09 s α 275Mt
280Rg syn 4.6 s α 276Mt
281Rg[6][7] syn 17 s SF (90%)
α (10%) 277Mt
282Rg[8] syn 100 s α 278Mt
283Rg[9] syn 5.1 min? SF
286Rg[10] syn 10.7 min? α 282Mt

History

Roentgen2
Roentgenium was named after the physicist Wilhelm Röntgen, the discoverer of X-rays.
Backdrop for presentation of Röntgenium, element 111, at GSI Darmstadt
Backdrop for presentation of the discovery and recognition of roentgenium at GSI Darmstadt

Official discovery

Roentgenium was first synthesized by an international team led by Sigurd Hofmann at the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany, on December 8, 1994.[11] The team bombarded a target of bismuth-209 with accelerated nuclei of nickel-64 and detected three nuclei of the isotope roentgenium-272:

209
83
Bi
+ 64
28
Ni
272
111
Rg
+ 1
0
n

This reaction had previously been conducted at the Joint Institute for Nuclear Research in Dubna (then in the Soviet Union) in 1986, but no atoms of 272Rg had then been observed.[12] In 2001, the IUPAC/IUPAP Joint Working Party (JWP) concluded that there was insufficient evidence for the discovery at that time.[13] The GSI team repeated their experiment in 2002 and detected three more atoms.[14][15] In their 2003 report, the JWP decided that the GSI team should be acknowledged for the discovery of this element.[16]

Naming

Using Mendeleev's nomenclature for unnamed and undiscovered elements, roentgenium should be known as eka-gold. In 1979, IUPAC published recommendations according to which the element was to be called unununium (with the corresponding symbol of Uuu),[17] 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 111, with the symbol of E111, (111) or even simply 111.[2]

The name roentgenium (Rg) was suggested by the GSI team[18] in 2004, to honor the German physicist Wilhelm Conrad Röntgen, the discoverer of X-rays.[18] This name was accepted by IUPAC on November 1, 2004.[18]

Isotopes

Roentgenium has no stable or naturally occurring isotopes. Several radioactive isotopes have been synthesized in the laboratory, either by fusion of the nuclei of lighter elements or as intermediate decay products of heavier elements. Nine different isotopes of roentgenium have been reported with atomic masses 272, 274, 278–283, and 286 (283 and 286 unconfirmed), two of which, roentgenium-272 and roentgenium-274, have known but unconfirmed metastable states. All of these decay through alpha decay or spontaneous fission,[19] though 280Rg may also have an electron capture branch.[20]

Stability and half-lives

List of roentgenium isotopes
Isotope Half-life[a] Decay
mode
Discovery
year[21]
Discovery
reaction[21]
Recent
publications
Ref NUBASE
2016[22]
272Rg 3.8 ms [14] 4.5 ms α 1994 209Bi(64Ni,n)
274Rg 14 ms[b] [23] 29 ms α 2004 278Nh(—,α)
278Rg 4.2 ms [24] 8 ms α 2006 282Nh(—,α)
279Rg 90 ms [24] 180 ms α 2003 287Mc(—,2α)
280Rg 4.6 s [24] 4.3 s α, EC 2003 288Mc(—,2α)
281Rg 17 s [24] 24 s SF, α 2010 293Ts(—,3α)
282Rg 1.7 min [24] 1.6 min α 2010 294Ts(—,3α)
283Rg[c] 5.1 min [9] SF 1999 283Cn(ee)
286Rg[c] 10.7 min [10] α 1998 290Fl(eeα)

All roentgenium isotopes are extremely unstable and radioactive; in general, the heavier isotopes are more stable than the lighter. The most stable known roentgenium isotope, 282Rg, is also the heaviest known roentgenium isotope; it has a half-life of 100 seconds. The unconfirmed 286Rg is even heavier and appears to have an even longer half-life of about 10.7 minutes, which would make it one of the longest-lived superheavy nuclides known; likewise, the unconfirmed 283Rg appears to have a long half-life of about 5.1 minutes. The isotopes 280Rg and 281Rg have also been reported to have half-lives over a second. The remaining isotopes have half-lives in the millisecond range.[19]

Predicted properties

Chemical

Roentgenium is the ninth 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.[25] Calculations on its ionization potentials and atomic and ionic radii are similar to that of its lighter homologue gold, thus implying that roentgenium's basic properties will resemble those of the other group 11 elements, copper, silver, and gold; however, it is also predicted to show several differences from its lighter homologues.[2]

Roentgenium is predicted to be a noble metal. Based on the most stable oxidation states of the lighter group 11 elements, roentgenium is predicted to show stable +5 and +3 oxidation states, with a less stable +1 state. The +3 state is predicted to be the most stable. Roentgenium(III) is expected to be of comparable reactivity to gold(III), but should be more stable and form a larger variety of compounds. Gold also forms a somewhat stable −1 state due to relativistic effects, and it has been suggested roentgenium may do so as well:[2] nevertheless, the electron affinity of roentgenium is expected to be around 1.6 eV (37 kcal/mol), significantly lower than gold's value of 2.3 eV (53 kcal/mol), so roentgenides may not be stable or even possible.[4] The 6d orbitals are destabilized by relativistic effects and spin–orbit interactions near the end of the fourth transition metal series, thus making the high oxidation state roentgenium(V) more stable than its lighter homologue gold(V) (known only in one compound) as the 6d electrons participate in bonding to a greater extent. The spin-orbit interactions stabilize molecular roentgenium compounds with more bonding 6d electrons; for example, RgF
6
is expected to be more stable than RgF
4
, which is expected to be more stable than RgF
2
. Roentgenium(I) is expected to be difficult to obtain.[2][26][27] Gold readily forms the cyanide complex Au(CN)
2
, which is used in its extraction from ore through the process of gold cyanidation; roentgenium is expected to follow suit and form Rg(CN)
2
.[28]

The probable chemistry of roentgenium has received more interest than that of the two previous elements, meitnerium and darmstadtium, as the valence s-subshells of the group 11 elements are expected to be relativistically contracted most strongly at roentgenium.[2] Calculations on the molecular compound RgH show that relativistic effects double the strength of the roentgenium–hydrogen bond, even though spin–orbit interactions also weaken it by 0.7 eV (16 kcal/mol). The compounds AuX and RgX, where X = F, Cl, Br, O, Au, or Rg, were also studied.[2][29] Rg+ is predicted to be the softest metal ion, even softer than Au+, although there is disagreement on whether it would behave as an acid or a base.[30][31] In aqueous solution, Rg+ would form the aqua ion [Rg(H2O)2]+, with an Rg–O bond distance of 207.1 pm. It is also expected to form Rg(I) complexes with ammonia, phosphine, and hydrogen sulfide.[31]

Physical and atomic

Roentgenium 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, due to its being expected to have different electron charge densities from them.[3] It should be a very heavy metal with a density of around 28.7 g/cm3; in comparison, the densest known element that has had its density measured, osmium, has a density of only 22.61 g/cm3. This results from roentgenium's high atomic weight, the lanthanide and actinide contractions, and relativistic effects, although production of enough roentgenium to measure this quantity would be impractical, and the sample would quickly decay.[2]

The stable group 11 elements, copper, silver, and gold, all have an outer electron configuration nd10(n+1)s1. For each of these elements, the first excited state of their atoms has a configuration nd9(n+1)s2. Due to spin-orbit coupling between the d electrons, this state is split into a pair of energy levels. For copper, the difference in energy between the ground state and lowest excited state causes the metal to appear reddish. For silver, the energy gap widens and it becomes silvery. However, as the atomic number increases, the excited levels are stabilized by relativistic effects and in gold the energy gap decreases again and it appears gold. For roentgenium, calculations indicate that the 6d97s2 level is stabilized to such an extent that it becomes the ground state and the 6d107s1 level becomes the first excited state. The resulting energy difference between the new ground state and the first excited state is similar to that of silver and roentgenium is expected to be silvery in appearance.[1] The atomic radius of roentgenium is expected to be around 138 pm.[2]

Experimental chemistry

Unambiguous determination of the chemical characteristics of roentgenium has yet to have been established[32] due to the low yields of reactions that produce roentgenium isotopes.[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.[25] Even though the half-life of 282Rg, the most stable known roentgenium isotope, is 100 seconds, long enough to perform chemical studies, another obstacle is the need to increase the rate of production of roentgenium 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 roentgenium isotopes and allow automated systems to experiment on the gas-phase and solution chemistry of roentgenium, as the yields for heavier elements are predicted to be smaller than those for lighter elements. However, the experimental chemistry of roentgenium has not received as much attention as that of the heavier elements from copernicium to livermorium,[2][32][33] despite early interest in theoretical predictions due to relativistic effects on the ns subshell in group 11 reaching a maximum at roentgenium.[2] The isotopes 280Rg and 281Rg are promising for chemical experimentation and may be produced as the granddaughters of the moscovium isotopes 288Mc and 289Mc respectively;[34] their parents are the nihonium isotopes 284Nh and 285Nh, which have already received preliminary chemical investigations.[35]

See also

References

  1. ^ Different sources give different values for half-lives; the most recently published values in the literature and NUBASE are both listed below for reference.
  2. ^ Derived from a mean lifetime of 2.0 ms
  3. ^ a b This isotope is unconfirmed
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External links

Darmstadt

Darmstadt (, also UK: , US: , German: [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.

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 12.7 seconds. 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.

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 (0.01 picoseconds, or 10 femtoseconds), 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 11 element

Group 11, by modern IUPAC numbering, is a group of chemical elements in the periodic table, consisting of copper (Cu), silver (Ag), and gold (Au). Roentgenium (Rg) is also placed in this group in the periodic table, although no chemical experiments have yet been carried out to confirm that it behaves like the heavier homologue to gold. Group 11 is also known as the coinage metals, due to their former usage. They were most likely the first three elements discovered. Copper, silver, and gold all occur naturally in elemental form.

Group 9 element

Group 9 is a group (column) of chemical elements in the periodic table. Members are cobalt (Co), rhodium (Rh), iridium (Ir) and meitnerium (Mt). These are all transition metals in the d-block.

Like other groups, the members of this family show patterns in electron configuration, especially in the outermost shells, resulting in trends in chemical behavior; however, rhodium deviates from the pattern.

"Group 9" is the modern standard designation for this group, adopted by the IUPAC in 1990.In the older group naming systems, this group was combined with group 8 (iron, ruthenium, osmium, and hassium) and group 10 (nickel, palladium, platinum, and darmstadtium) and called group "VIIIB" in the Chemical Abstracts Service (CAS) "U.S. system", or "VIII" in the old IUPAC (pre-1990) "European system" (and in Mendeleev's original table).

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 meitnerium

Meitnerium (109Mt) 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 266Mt in 1982, and this is also the only isotope directly synthesized; all other isotopes are only known as decay products of heavier elements. There are eight known isotopes, from 266Mt to 278Mt. There may also be two isomers. The longest-lived of the known isotopes is 278Mt with a half-life of 8 seconds. The unconfirmed heavier 282Mt appears to have an even longer half-life of 67 seconds.

Isotopes of roentgenium

Roentgenium (111Rg) 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 272Rg in 1994, which is also the only directly synthesized isotope; all others are decay products of nihonium, moscovium, and tennessine, and possibly copernicium, flerovium, and livermorium. There are 7 known radioisotopes from 272Rg to 282Rg. The longest-lived isotope is 282Rg with a half-life of 2.1 minutes, although the unconfirmed 283Rg and 286Rg may have a longer half-life of about 5.1 minutes and 10.7 minutes respectively.

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.

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.

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'.

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.

UUU

UUU, Uuu, or UuU may refer to:

Uranium One (TSX: UUU, JSE: UUU), Canadian based uranium mining company

UUU, or uracil uracil uracil, the RNA codon for phaAwenylalanine

Unununium (Uuu), the former name of a chemical element now called Roentgenium (Rg)

WUUU-FM, a country music outlet based out of Franklinton, Louisiana

The Triple U Buffalo Ranch in Stanley county, South Dakota

UUU, the production code for the 1973–74 Doctor Who serial The Time Warrior

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.

Wilhelm Röntgen

Wilhelm Conrad Röntgen (; German: [ˈvɪlhɛlm ˈʁœntɡən]; 27 March 1845 – 10 February 1923) was a German mechanical engineer and physicist, who, on 8 November 1895, produced and detected electromagnetic radiation in a wavelength range known as X-rays or Röntgen rays, an achievement that earned him the first Nobel Prize in Physics in 1901. In honour of his accomplishments, in 2004 the International Union of Pure and Applied Chemistry (IUPAC) named element 111, roentgenium, a radioactive element with multiple unstable isotopes, after him.

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