Fermium, Nobelium , Lawrencium , Rutherfordium , Dubnium
Mendelevium is a synthetic element with the symbol Md (formerly Mv) and the atomic number 101. A metallic radioactivetransuranic element in the actinide series, mendelevium is usually synthesized by bombarding einsteinium with alpha particles. It was named after Dmitri Ivanovich Mendeleev, who created the Periodic Table. Sony VAIO VGN-SR290JTQ Battery
Mendeleev's periodic system is the fundamental way to classify all the chemical elements. The name "mendelevium" was accepted by the International Union of Pure and Applied Chemistry (IUPAC). On the other hand, the proposed symbol "Mv" submitted by the discoverers was not accepted, and the IUPAC selected "Md" instead. Sony VAIO VGN-SR290JVH/C Battery,Sony VAIO VGN-SR290NTB Battery
Researchers have shown that mendelevium has a moderately stable dipositive (II) oxidation state in addition to the more characteristic (for actinide elements) tripositive (III) oxidation state, the latter being the more dominantly exhibited state in an aqueous solution (chromatography being the process used). Sony VAIO VGN-SR29VN/S Battery
Sometimes, mendelevium can even be shown to exhibit a monopositive (I) state. 256Md has been used to find out some of the chemical properties of this element while in an aqueoussolution. There are no other known uses of mendelevium and only trace amounts of the element have ever been produced. Sony VAIO VGN-SR29XN/S Battery
Otherisotopes of mendelevium, all radioactive, have been discovered, with 258Md being the most stable with a two-month half-life (about 55 days). Other isotopes range from 248 to 258 mass numbers and half-lives from a few seconds to about 51 days. The original 256Md had a half-life of 87 minutes. Sony VAIO VGN-SR390NAB Battery
The radioactivity of the trivalent element, mendelevium, is definitely noteworthy. It was expected that the reaction would be253Es (?,n) 255Md, where 255Md was ?-active with a t½ of 5 minutes and the corresponding ?-energy. No such ?-activity was observed, but the 101 fraction showed spontaneous fission representing a t½ less than 3 hours. Sony VAIO VGN-SR41M/P Battery,Sony VAIO VGN-SR41M/S Battery
Because spontaneous fission was also observed in the fraction containing fermium, the ?-bombardment of 253Einsteinium (Es) produced 256Md. The latter underwent electron capture to become 256Fermium (Fm), which then decayed by spontaneous fission. So 256Fm was produced by the decays of cyclotron-synthesized mendelevium. Sony VAIO VGN-SR49VN/H Battery
Johansson and Rosengren predicted in 1975 that Md would prefer a divalent metallic state, similar to europium (Eu) andytterbium(Yb), rather than a trivalent one. Thermochromatographic studies conducted with trace amounts of Md concluded that Md forms a divalent metal. Sony VAIO VGN-SR51B/P Battery
With the aid of empirical correlation method, a divalent metallic radius of (0.194 ± 0.010) nmhas been estimated. The estimated enthalpy of sublimation is in the range of 134-142 kJ/mol.
Before the actual discovery of mendelevium, the trivalent state was the most stable one in aqueous solution. Sony VAIO VGN-SR51B/S Battery
Accordingly, a similar chemical behavior to the other 3+ actinides and lanthanides was expected. The elution of Md just before Fm in theelution sequence of the trivalent actinides from the cation-exchange resin column, confirmed this prediction. Afterwards, Md in the form of insoluble hydroxides and fluorides that are quantitatively coprecipitated with trivalent lanthanides was found. Sony VAIO VGN-SR51MF/P Battery
The cation-exchange resin column as well as the HDEHP solvent extraction column elution date is consistent with a trivalent state for Md and an ionic radius smaller than Fm. An ionic radius of 0.0192 nm and a coordination number of 6 for Md3+ was predicted using empirical correlations. Sony VAIO VGN-SR51MF/S Battery
Using the known ionic radii for the trivalent rare earths and the linear correlation of log distribution coefficient with ionic radius, an average ionic radius of 0.089 nm was estimated for Md3+ and a heat of hydration of – (3654 ± 12) kJ/mol calculated using empirical models and the Born-Haber cycle. Sony VAIO VGN-SR51MF/W Battery
In reducing conditions, an anomalous chemical behavior of Md was found. Coprecipitation with BaSO4and solvent extraction chromatography experiments using HDEHP were carried out in different reducing agents. These showed that Md3+ could easily be reduced to a stable Md2+ in aqueous solution. Mendelevium can also be reduced to the monovalent state in water-ethanol solutions.Sony VAIO VGN-SR59VG Battery
The cocrystallization of Md+ with salts of divalent ions is due to the formation of mixed crystals. For Md+, an ionic radius of 0.117 nm was found. The oxidation of Md3+ to Md4+ was rather unsuccessful. Sony VAIO VGN-SR59VG/H Battery
Mendelevium (for Dimitri Ivanovich Mendeleev, surname commonly transliterated into Latin script as Mendeleev, Mendeleyev, Mendeléef, or even Mendelejeff, and first name sometimes transliterated as Dmitry or Dmitriy) was first synthesized by Albert Ghiorso, Glenn T. Seaborg, Gregory R. Choppin, Bernard G. Harvey, and Stanley G. Thompson (team leader) in early 1955 at the University of California, Berkeley. Sony VAIO VGN-SR70B/S Battery
The team produced 256Md (half-life of 87 minutes) when they bombarded an 253Es target with alpha particles (helium nuclei) in the Berkeley Radiation Laboratory's 60-inch cyclotron (256Md was the first isotope of any element to be synthesized one atom at a time). Element 101 was the ninth transuranic element synthesized. Sony VAIO VGN-SR72B/S Battery
The first 17 atoms of this element were created and analyzed using the ion-exchange adsorption-elution method. During the process, mendelevium behaved very much like thulium, its naturally occurring homologue.
Discovery in detail
The discovery was based on a grand total of only 17 atoms. Sony VAIO VGN-SR73JB/S Battery
It is synthesized via the 253Es (?,n) 256101 reaction in the 60-Inch-Cyclotron (= 152 cm) at Berkeley (California). The target can be produced by irradiation of lighter isotopes as plutonium in the Materials Testing Reactor at the Arco Reactor Station in Idaho. Remarkable is that this target consisted of only 109 atoms of highly radioactive 253Es (with a half-life of 20.5 days). Sony VAIO VGN-SR74FB/S Battery
By elution through a calibrated cation exchange resin column, mendelevium was separated and chemically identified.
To predict if this method would be possible, they made use of a rough calculation. Sony VAIO VGN-SR90NS Battery
The number of atoms that would be produced, would be approximately equal to the number of atoms of target material times its cross section times the ion beam intensity times the time of bombardment related to the half-life of the product when bombarding for a time of the order of its half-life). This gave 1 atom per experiment. Sony VAIO VGN-SR90S Battery
Thus under optimum conditions, the preparation of only one atom of element 101 per experiment could be expected. This calculation demonstrated that it was feasible to go ahead with the experiment.
The actual synthesis was done by a recoil technique, introduced by Albert Ghiorso. Sony VAIO VGN-SR90US Battery
In this technique, the target element was placed on the opposite side of the target from the beam and caught the recoiling atoms on a catcher foil. This recoil target was made by an electroplating technique, developed by Alfred Chetham-Strode. This technique gave a very high yield, which is absolutely necessary when working with such a rare product as the einsteinium target material. Sony VAIO VGN-SR91NS Battery
The recoil target consisted of 10?9 of 253Es which were deposited electrolytically on a thin gold foil (also Be, Al and Pt can be used). It was bombarded by 41 eV ?-particles in the Berkeley cyclotron with a very high beam density of 6?1013 particles per second over an area of 0.05 cm2. The target was cooled by water or liquid helium. Sony VAIO VGN-SR91S Battery
The use of helium, in a gaseous atmosphere, slowed down the recoil atoms. This gas could be pumped out of the reaction chamber through a small orifice to form a ‘gas-jet’. Some fraction of the nonvolatile product atoms carried along with the gas, were deposited permanently on the foil surface. The foil could be removed periodically and a new foil could be installed. Sony VAIO VGN-SR91US Battery
The next reaction was used for the mendelevium discovery experiment: 253Es + 4He ? 256Md + 1n.
Purification and isolation
The removal of the Md atoms from the collector foil was done by acid etching or total dissolution of the thin gold foil. They can be purified and isolated from other product activities by several techniques. Sony VAIO VGN-SR92PS Battery
Separation of trivalent actinides from lanthanide fission products and La carrier can be done by a cation-exchange resin column using a 90% water/10% ethanol solution saturated with HClas eluant. To separate Md rapidly from the catcher foil, an anion-exchange chromatography using 6M HCl as eluant can be used. The gold remained on the column while the Md and other actinides passed through. Sony VAIO VGN-SR92US Battery
A final isolation of Md3+ from other trivalent actinides was also required. To separate fractions containing elements 99, 100 and 101, a cation-exchange resin column (Dowex-50 exchange column) treated with ammonium salts was used. A chemical identification was made on the basis of its elution position just before Fm. In series of repetitive experiments, they made use of the eluant: ?-hydroxyisobutyrate solution (?-HIB). Sony VAIO VGN-SR93JS Batery
Using the ‘gas-jet’ method, the first two steps can be eliminated. There was shown that in this method it is possible to transport and collect individual product atoms in a fraction of a second some tens of meters away from the target area. Effective transport over long distances requires the presence of large clusters (KCl aerosols) in the ‘carrier’ gas. It is used frequently in the production and isolation of transeinsteinium elements. Sony VAIO VGN-SR93YS Battery
Another possible way to separate the 3+ actinides can be achieved by solvent extraction chromatography using bis-(2-ethylhexyl) phosphoric acid (abbreviated as HDEHP) as the stationary organic phase and HNO3 as the mobile aqueous phase. The actinide elution sequence is reversed from that of the cation-exchange resin column. Sony VAIO VGN-SR94GS Battery
The Md separated by this method has the advantage to be free of organic complexing agent compared to the resin column. The disadvantage of this method is that Md elutes after Fm late in the sequence.
The first "Hooray!"
The data sheet, showing stylus tracing and notes, that proved the discovery of mendelevium. Sony VAIO VGN-SR94HS Battery
There was no direct detection, but by observation of spontaneous fission events arising from its electron-capture daughter 256Fm. These events were recorded during the night of February 19, 1955. The first one was identified with a "hooray" followed by a "double hooray" and a "triple hooray". Sony VAIO VGN-SZ35B/B Battery
The fourth one eventually officially proved the chemical identification of the 101st element, mendelevium. Additional analysis and further experimentation, showed the isotope to have mass 256 and to decay by electron capture with a half-life of 1.5 h. Sony VAIO VGN-SZ55B/B Battery
Sixteen isotopes of mendelevium from mass 245 to 260 have been characterized, with the most stable being 258Md with a half-life of 51.5 days, 260Md with a half-life of 31.8 days, and 257Md with a half-life of 5.52 hours. All of the remaining radioactiveisotopes have half-lives that are less than 97 minutes, and the majority of these have half-lives that are less than 5 minutes. Sony VAIO VGN-SZ55GN/B Battery
This element also has 5 meta states, with the longest-lived being 258mMd (t½ = 58 minutes). The isotopes of mendelevium range inatomic weight from 245.091 u (245Md) to 260.104 u (260Md).
Nobelium is a synthetic element with the symbol No andatomic number 102. Sony VAIO VGN-SZ561N Battery
It was first correctly identified in 1966 by scientists at the Flerov Laboratory of Nuclear Reactions in Dubna, Soviet Union. Little is known about the element but limited chemical experiments have shown that it forms a stable divalent ion in solution as well as the predicted trivalent ion that is associated with its presence as one of the actinoids. Sony VAIO VGN-SZ562N Battery
The discovery of element 102 was first announced by physicists at the Nobel Institute in Sweden in 1957. The team reported that they created an isotope with a half-life of 10 minutes, decaying by emission of an 8.5 MeV alpha particle, after bombarding 244Cm with 13C nuclei. Sony VAIO VGN-SZ58GN Battery
The activity was assigned to 251No or 253No. The scientists proposed the name nobelium (No) for the new element. Later they retracted their claim and associated the activity to background effects.
The synthesis of element 102 was then claimed in April 1958 at the University of California, Berkeley by Albert Ghiorso, Glenn T. Seaborg, John R. Walton and Torbjørn Sikkeland. Sony VAIO VGN-SZ58N Battery
The team used the new heavy-ion linear accelerator(HILAC) to bombard a curiumtarget (95% 244Cm and 5% 246Cm) with 13C and 12C ions. They were unable to confirm the 8.5 MeV activity claimed by the Swedes but were instead able to detect decays from 250Fm, supposedly the daughter of254102, which had an apparent half-life of ~3 s. Sony VAIO VGN-SZ61VN/X Battery
In 1959 the team continued their studies and claimed that they were able to produce an isotope that decayed predominantly by emission of an 8.3 MeV alpha particle, with a half-life of 3 s with an associated 30% spontaneous fission branch. The activity was initially assigned to 254No but later changed to 252No. The Berkeley team decided to adopt the name nobelium for the element.Sony VAIO VGN-SZ61WN/C Battery
Further work in 1961 on the attempted synthesis of element 103 produced evidence for a Z=102 alpha activity decaying by emission of an 8.2 MeV particle with a half-life of 15 s, and assigned to 255No. Sony VAIO VGN-SZ645P3 Battery
Following initial work between 1958–1964, in 1966, a team at the Flerov Laboratory of Nuclear Reactions (FLNR) reported that they had been able to detect 250Fm from the decay of a parent nucleus (254No) with a half-life of ~50s, in contradiction to the Berkeley claim. Furthermore, they were able to show that the parent decayed by emission of 8.1 MeV alpha particles with a half-life of ~35 s.Sony VAIO VGN-SZ650N/C Battery
In 1969, the Dubna team carried out chemical experiments on element 102 and concluded that it behaved as the heavier homologue of ytterbium. The Russian scientists proposed the name joliotium (Jo) for the new element.
Later work in 1967 at Berkeley and 1971 at Oak Ridge fully confirmed the discovery of element 102 and clarified earlier observations.Sony VAIO VGN-SZ670N/C Battery
In 1992, the IUPAC-IUPAP Transfermium Working Group (TWG) assessed the claims of discovery and concluded that only the Dubna work from 1966 correctly detected and assigned decays to Z=102 nuclei at the time. The Dubna team are therefore officially recognised as the discoverers of nobelium although it is possible that it was detected at Berkeley in 1959. Sony VAIO VGN-SZ691N/X Battery
Element 102 was first named nobelium (No) by its claimed discoverers in 1957 by scientists at the Nobel Institute in Sweden. The name was later adopted by Berkeley scientists who claimed its discovery in 1959. Sony VAIO VGN-SZ71VN/X Battery
The International Union of Pure and Applied Chemistry (IUPAC) officially recognised the name nobelium following the Berkeley results.
In 1994, and subsequently in 1997, the IUPAC ratified the name nobelium (No) for the element on the basis that it had become entrenched in the literature over the course of 30 years and that Alfred Nobel should be commemorated in this fashion. Sony VAIO VGN-SZ71WN/C Battery,Sony VAIO VGN-SZ74B/B Battery
The appearance of this element is unknown, however it is most likely silvery-white or gray and metallic. If sufficient amounts of nobelium were produced, it would pose a radiation hazard. Some sources quote a melting point of 827 °C for nobelium but this cannot be substantiated from an official source and seems implausible regarding the requirements of such a measurement. Sony VAIO VGN-SZ750N/C Battery
However, the 1st, 2nd and 3rd ionization energies have been measured. In addition, an electronegativity value of 1.3 is also sometimes quoted.
Aqueous phase chemistry
First experiments involving nobelium assumed that it predominantly formed a +III state like earlier actinoids. Sony VAIO VGN-SZ76 Battery
However, it was later found that nobelium forms a stable +II state in solution, although it can be oxidised to an oxidising +III state. A reduction potential of ?1.78 V has been measured for the No3+ ion. The hexaaquanobelium(II) ion has been determined to have an ionic radius of 110 pm. Sony VAIO VGN-SZ770N/C Battery
Summary of compounds and (complex) ions
Twelve radioisotopes of nobelium have been characterized, with the most stable being 259No with a half-life of 58 minutes. Longer half-lives are expected for the as-yet-unknown 261No and 263No. An isomeric level has been found in 253No and K-isomers have been found in 250No, 252No and 254No to date. Sony VAIO VGN-SZ780 Battery,Sony VAIO VGN-SZ78N Battery,Sony VAIO VGN-SZ791N/X Battery
Synthesis of isotopes as decay products
Isotopes of nobelium have also been identified in the decay of heavier elements. Observations to date are summarised in the table below:
Isomerism in nobelium nuclides
254No The study of K-isomerism was recently studied by physicists at the University of Jyväskylä physics laboratory (JYFL). Sony VAIO VGN-SZ84NS Battery
They were able to confirm a previously reported K-isomer and detected a second K-isomer. They assigned spins and parities of 8- and 16+to the two K-isomers.
253No In 1971, Bemis et al. was able to determine an isomeric level decaying with a half-life of 31 µs from the decay of 257Rf. Sony VAIO VGN-SZ84S Battery
This was confirmed in 2003 at the GSI by also studying the decay of 257Rf. Further support in the same year from the FLNR appeared with a slightly higher half-life of 43.5 µs, decaying by M2 gamma emission to the ground state.
252No In a recent study by the GSI into K-isomerism in even-even isotopes, a K-isomer with a half-life of 110 ms was detected for 252No. Sony VAIO VGN-SZ85NS Battery
A spin and parity of 8- was assigned to the isomer.
250No In 2003, scientists at the FLNR reported that they had been able to synthesise 249No which decayed by SF with a half-life of 54µs. Further work in 2006 by scientists at the ANL showed that the activity was actually due to a K-isomer in 250No. The ground state isomer was also detected with a very short half-life of 3.7µs. Sony VAIO VGN-SZ85US Battery,Sony VAIO VGN-SZ94NS Battery
The table below provides cross-sections and excitation energies for cold fusion reactions producing nobelium isotopes directly. Data in bold represents maxima derived from excitation function measurements. + represents an observed exit channel. Sony VAIO VGN-SZ94PS Battery
The table below provides cross-sections and excitation energies for hot fusion reactions producing nobelium isotopes directly. Data in bold represents maxima derived from excitation function measurements. + represents an observed exit channel. Sony VAIO VGN-SZ94US Battery?Sony VAIO VGN-SZ95NS Battery
In 2003, scientists at the FLNR claimed to have discovered the lightest known isotope of nobelium. However, subsequent work showed that the 54 µs activity was actually due to 250No and the isotope 249No was retracted. Sony VAIO VGN-SZ95S Battery
Lawrencium is a radioactive synthetic chemical element with the symbol Lr and atomic number 103. In the periodic table of the elements, it is a period 7 d-block element and the last element of actinideseries. Chemistry experiments have confirmed that lawrencium behaves as the heavier homologue to lutetium and is chemically similar to other actinides. Sony VAIO VGN-TZ121 Battery,Sony VAIO VGN-TZ13 Battery
Lawrencium was first synthesized by the nuclear-physics team led by Albert Ghiorso on February 14, 1961, at theLawrence Berkeley National Laboratory of the University of California. Sony VAIO VGN-TZ130N/B Battery
The first atoms of lawrencium were produced by bombarding a three-milligram target consisting of three isotopes of the element californium with boron-10 and boron-11 nuclei from the Heavy Ion Linear Accelerator. The team suggested the name lawrencium, and the symbol Lw, but Lr was officially accepted instead. It was the last element of actinide series produced. Sony VAIO VGN-TZ131 Battery,Sony VAIO VGN-TZ132/N Battery
All isotopes of lawrencium are radioactive; its most stable known isotope is lawrencium-262, with a half-life of approximately 3.6 hours. All its isotopes except for lawrencium-260, -261 and -262 decay with a half-life of less than a minute. Sony VAIO VGN-TZ132N Battery
Lawrencium was first synthesized by the nuclear-physics team of Albert Ghiorso, Torbjørn Sikkeland, Almon Larsh, Robert M. Latimer, and their co-workers on February 14, 1961, at the Lawrence Radiation Laboratory (now called theLawrence Berkeley National Laboratory) at the University of California. Sony VAIO VGN-TZ150N/B Battery
The first atoms of lawrencium were produced by bombarding a three-milligramtarget consisting of three isotopes of the element californium with boron-10 and boron-11nuclei from the Heavy Ion Linear Accelerator (HILAC). The Berkeley team reported that the isotope 257Lr was detected in this manner, and that it decayed by emitting an 8.6 MeV alpha particle with a half-life of about eight seconds. Sony VAIO VGN-TZ150N/N Battery?Sony VAIO VGN-TZ160CB Battery
This identification was later corrected to be 258Lr.
In 1967, nuclear-physics researchers in Dubna, Russia, reported that they were not able to confirm assignment of an alpha emitter with a half-life of eight seconds to 257Lr. This isotope was later deduced to be 258Lr. Instead, the Dubna team reported an isotope with a half-life of about 45 seconds as 256Lr. Sony VAIO VGN-TZ160N/B Battery?Sony VAIO VGN-TZ16GN/B Battery
Further experiments have demonstrated an actinide chemistry for the new element, so by 1970 it was known that lawrencium is an actinide, and what is more, the last one. In 1971, the nuclear physics team at the University of California at Berkeley successfully performed a whole series of experiments aimed at measuring the nuclear decay properties of the lawrencium isotopes with mass numbers from 255 through 260. Sony VAIO VGN-TZ16N Battery,Sony VAIO VGN-TZ16N/B Battery
In 1992, the IUPAC Trans-fermium Working Group (TWG) officially recognized the nuclear physics teams at Dubna and Berkeley as the co-discoverers of lawrencium.
The origin of the name, ratified by the American Chemical Society, is in reference to the nuclear-physicist Ernest O. Lawrence, of the University of California, who invented the cyclotron particle accelerator. Sony VAIO VGN-TZ17/N Battery?Sony VAIO VGN-TZ170N/B Battery
The symbol Lw was used originally, but the element was assigned the Lr symbol. In August 1997, the International Union of Pure and Applied Chemistry (IUPAC) ratified the name lawrencium and the symbol Lr during a meeting in Geneva. Sony VAIO VGN-TZ170N/N Battery
Lawrencium is element 103 in the periodic table. It is the first member of the 6d-block; in accordance with theMadelung rule, its electronic configuration should be [Rn]7s25f146d1. However, results from quantum mechanical research have suggested that this configuration is incorrect, and is in fact [Rn]7s25f147p1. Sony VAIO VGN-TZ17GN/B Battery?Sony VAIO VGN-TZ17N Battery
A direct measurement of this is not possible. Though early calculations gave conflicting results, more recent studies and calculations confirm the suggestion.
A strict correlation between the periodic table blocks and the orbital-shell configurations for neutral atoms would classify lawrencium as a transition metal because it could be classed as a d-block element. Sony VAIO VGN-TZ18/N Battery?Sony VAIO VGN-TZ180N/RC Battery
However, lawrencium is classified as an actinide element according to the IUPAC
Experimental chemical properties
The first gaseous-phase studies of lawrencium were reported in 1969 by a nuclear-physics team at the FlerovLaboratory of Nuclear Reactions (FLNR) in the Soviet Union. Sony VAIO VGN-TZ185N/WC Battery
They used the nuclear reaction 243Am+18O to produce lawrencium nuclei, which they then exposed to a stream of chlorine gas, and a volatile chloride product was formed. This product was deduced to be 256LrCl3, and this confirmed that lawrencium is a typical actinide element. Sony VAIO VGN-TZ18N Battery
The first aqueous-phase studies of lawrencium were reported in 1970 by a nuclear-physics team at the Lawrence Berkeley National Laboratory in California. This team used the nuclear reaction 249Cf+11B to produce lawrencium nuclei. Sony VAIO VGN-TZ190N/B Battery
They were able to show that lawrencium forms a trivalent ion, similar to those of the other actinide elements, but in contrast with that of nobelium. Further experiments in 1988 confirmed the formation of a trivalent lawrencium(III) ion using anion-exchange chromatography using ?-hydroxyisobutyrate (?-HIB) complex. Sony VAIO VGN-TZ190N/BC Battery
Comparison of the elution time with other actinides allowed a determination of 88.6 picometers for the ionic radius for Lr3+. Attempts to reduce lawrencium in the lawrencium(III) ionization state to lawrencium(I) using the potent reducing agent hydroxylamine hydrochloride were unsuccessful. Sony VAIO VGN-TZ191N/XC Battery
This reaction was studied in a series of experiments in 1976 by Yuri Oganessian and his team at the FLNR. Evidence was provided for the formation of 253Lr in the 2n exit channel. Sony VAIO VGN-TZ250N/B Battery
This reaction was studied in a series of experiments in 1976 by Yuri Oganessian and his team at the FLNR.
This reaction was reported in 1984 by Yuri Oganessian at the FLNR. The team was able to detect decays of 246Cf, a descendant of 254Lr. Sony VAIO VGN-TZ250N/N Battery
This reaction was studied in a series of experiments in 1976 by Yuri Oganessian and his team at the FLNR. Results are not readily available.
This reaction has been used to study the spectroscopic properties of 255Lr. Sony VAIO VGN-TZ250N/P Battery
The team at GANIL used the reaction in 2003 and the team at the FLNR used it between 2004-2006 to provide further information for the decay scheme of 255Lr. The work provided evidence for an isomeric level in 255Lr.
This reaction was first studied in 1965 by the team at the FLNR. They were able to detect activity with a characteristic decay of 45 seconds, which was assigned to256Lr or 257Lr. Sony VAIO VGN-TZ27/N Battery
Later work suggests an assignment to 256Lr. Further studies in 1968 produced an 8.35–8.60 MeV alpha activity with a half-life of 35 seconds. This activity was also initially assigned to 256Lr or 257Lr and later to solely 256Lr.
This reaction was studied in 1970 by the team at the FLNR. They were able to detect an 8.38 MeV alpha activity with a half-life of 20s. This was assigned to 255Lr. Sony VAIO VGN-TZ27N Battery
This reaction was studied in 1971 by the team at the LBNL in their large study of lawrencium isotopes. They were able to assign alpha activities to 260Lr,259Lr and258Lr from the 3-5n exit channels. Sony VAIO VGN-TZ285N/RC Battery
This reaction was studied in 1988 at the LBNL in order to assess the possibility of producing 262Lr and 261Lr without using the exotic 254Es target. It was also used to attempt to measure an electron capture (EC) branch in 261mRf from the 5n exit channel.Sony VAIO VGN-TZ28N Battery
After extraction of the Lr(III) component, they were able to measure thespontaneous fission of 261Lr with an improved half-life of 44 minutes. The production cross-section was 700 pb. On this basis, a 14% electron capture branch was calculated if this isotope was produced via the 5n channel rather than the p4n channel. Sony VAIO VGN-TZ290EAB Battery,Sony VAIO VGN-TZ290EAN Battery
A lower bombarding energy (93 MeV c.f. 97 MeV) was then used to measure the production of 262Lr in the p3n channel. The isotope was successfully detected and a yield of 240 pb was measured. The yield was lower than expected compared to the p4n channel. Sony VAIO VGN-TZ290EAP Battery
However, the results were judged to indicate that the 261Lr was most likely produced by a p3n channel and an upper limit of 14% for the electron capture branch of 261mRf was therefore suggested.
This reaction was studied briefly in 1958 at the LBNL using an enriched 244Cm target (5% 246Cm). Sony VAIO VGN-TZ295N/XC Battery
They observed a ~9 MeV alpha activity with a half-life of ~0.25 seconds. Later results suggest a tentative assignment to 257Lr from the 3n channel
This reaction was studied briefly in 1958 at the LBNL using an enriched 244Cm target (5% 246Cm). They observed a ~9 MeV alpha activity with a half-life of ~0.25s. Sony VAIO VGN-TZ33/B Battery
Later results suggest a tentative assignment to 257Lr from the 3n channel with the 246Cm component. No activities assigned to reaction with the 244Cm component have been reported.
This reaction was studied in 1971 by the team at the LBNL in their large study of lawrencium isotopes. They were able to detect an activity assigned to 260Lr. Sony VAIO VGN-TZ33/W Battery
The reaction was further studied in 1988 to study the aqueous chemistry of lawrencium. A total of 23 alpha decays were measured for 260Lr, with a mean energy of 8.03 MeV and an improved half-life of 2.7 minutes. The calculated cross-section was 8.7 nb. Sony VAIO VGN-TZ350N/N Battery
This reaction was first studied in 1961 at the University of California by Albert Ghiorso by using a californium target (52% 252Cf). They observed three alpha activities of 8.6, 8.4 and 8.2 MeV, with half-lives of about 8 and 15 seconds, respectively. Sony VAIO VGN-TZ350N/P Battery
The 8.6 MeV activity was tentatively assigned to 257Lr. Later results suggest a reassignment to 258Lr, resulting from the 5n exit channel. The 8.4 MeV activity was also assigned to 257Lr. Later results suggest a reassignment to 256Lr. This is most likely from the 33% 250Cf component in the target rather than from the 7n channel. The 8.2 MeV was subsequently associated with nobelium. Sony VAIO VGN-TZ370N/B Battery
This reaction was first studied in 1961 at the University of California by Albert Ghiorso by using a californium target (52% 252Cf). They observed three alpha activities of 8.6, 8.4 and 8.2 MeV, with half-lives of about 8 and 15 seconds, respectively. Sony VAIO VGN-TZ37N/P Battery
The 8.6 MeV activity was tentatively assigned to 257Lr. Later results suggest a reassignment to 258Lr. The 8.4 MeV activity was also assigned to 257Lr. Later results suggest a reassignment to 256Lr. The 8.2 MeV was subsequently associated with nobelium. Sony VAIO VGN-TZ37N/R Battery
This reaction was studied in 1971 at the LBNL. They were able to identify a 0.7s alpha activity with two alpha lines at 8.87 and 8.82 MeV. This was assigned to257Lr.
This reaction was first studied in 1970 at the LBNL in an attempt to study the aqueous chemistry of lawrencium. Sony VAIO VGN-TZ37N/X Battery
They were able to measure a Lr3+ activity. The reaction was repeated in 1976 at Oak Ridge and 26s 256Lr was confirmed by measurement of coincident X-rays.
This reaction was studied in 1971 by the team at the LBNL. They were able to detect an activity assigned to 258Lr from the p2n channel. Sony VAIO VGN-TZ398U/XC Battery
This reaction was studied in 1971 by the team at the LBNL. They were able to detect an activities assigned to 258Lr and 257Lr from the ?2n and ?3n and channels. The reaction was repeated in 1976 at Oak Ridge and the synthesis of 258Lr was confirmed. Sony VAIO VGN-TZ90HS Battery
254Es + 22Ne – transfer
This reaction was studied in 1987 at the LLNL. They were able to detect new spontaneous fission (SF) activities assigned to 261Lr and 262Lr, resulting from transfer from the 22Ne nuclei to the 254Es target. In addition, a 5 ms SF activity was detected in delayed coincidence with nobelium K-shell X-rays and was assigned to 262No, resulting from the electron capture of 262Lr. Sony VAIO VGN-TZ90NS Battery
Isotopes of lawrencium have also been identified in the decay of heavier elements. Observations to date are summarised in the table below:
Eleven isotopes of lawrencium plus one isomer have been synthesized with 262Lr being the longest-lived and the heaviest, with a half-life of 216 minutes. Sony VAIO VPC CW2MFX/PU Battery
252Lr is the lightest isotope of lawrencium to be produced to date.
A study of the decay properties of 257Db (see dubnium) in 2001 by Hessberger et al. at the GSI provided some data for the decay of 253Lr. Analysis of the data indicated the population of two isomeric levels in 253Lr from the decay of the corresponding isomers in 257Db. Sony VAIO VPC S11V9E/B Battery
The ground state was assigned spin and parity of 7/2-, decaying by emission of an 8794 KeV alpha particle with a half
Rutherfordium is a chemical element with symbol Rf and atomic number 104, named in honor of New Zealand physicist Ernest Rutherford. It is a synthetic element (an element that can be created in a laboratory but is not found in nature) and radioactive; the most stable known isotope, 267Rf, has a half-life of approximately 1.3 hours. Sony VAIO VPCB11AGJ Battery,Sony VAIO VPCB11AVJ Battery
In the periodic table of the elements, it is a d-block element and the first of the transactinide elements. It is a member of the 7th period and belongs to the group 4 elements. Chemistry experiments have confirmed that rutherfordium behaves as the heavier homologue to hafnium in group 4. Sony VAIO VPCB11V9E Battery,Sony VAIO VPCB11X9E Battery
The chemical properties of rutherfordium are characterized only partly. They compare well with the chemistry of the other group 4 elements, even though some calculations had indicated that the element might show significantly different properties due to relativistic effects. Sony VAIO VPCCW18FJ/P Battery
In the 1960s, small amounts of rutherfordium were produced in laboratories in the former Soviet Union and in California. 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 rutherfordium as the official name for the element. Sony VAIO VPCCW18FJ/R Battery,Sony VAIO VPCCW18FJ/W Battery
Rutherfordium was reportedly first detected in 1966 at the Joint Institute of Nuclear Research at Dubna (then in theSoviet Union). Researchers there bombarded a plutonium-242 target with neon-22 ions and separated the reaction products by gradient thermochromatography after conversion to chlorides by interaction with ZrCl4. Sony VAIO VPCCW19FJ/W Battery?Sony VAIO VPCCW1AFJ Battery
The team identified spontaneous fission activity contained within a volatile chloride portraying eka-hafnium properties. Although a half-life was not accurately determined, later calculations indicated that the product was most likely rutherfordium-259 (or simply259Rf): Sony VAIO VPCCW1AHJ Battery
In 1969, researchers at the University of California, Berkeley conclusively synthesized the element by bombarding acalifornium-249 target with carbon-12 ions and measured the alpha decay of 257Rf, correlated with the daughter decay ofnobelium-253: Sony VAIO VPCCW1S1E Battery
The American synthesis was independently confirmed in 1973 and secured the identification of rutherfordium as the parent by the observation of K-alpha X-rays in the elemental signature of the 257Rf decay product, nobelium-253.  Sony VAIO VPCCW1S1E/B Battery
The 104th element was eventually named after Ernest Rutherford (left side) (1871–1937), a British-New Zealand chemist and physicist who became known as the father of nuclear physics. Sony VAIO VPCCW1S1E/L Battery
The element was initially proposed to be named after Igor Kurchatov(right side) (1903–1960), a Soviet nuclear physicist who is remembered as "The Father of the Soviet Atomic Bomb".
The Russian scientists proposed the name kurchatovium and the American scientists suggested the name rutherfordium for the new element. Sony VAIO VPCCW1S1E/P Battery
In 1992, the IUPAC/IUPAPTransfermium Working Group (TWG) assessed the claims of discovery and concluded that both teams provided contemporaneous evidence to the synthesis of element 104 and that credit should be shared between the two groups.
The American group wrote a scathing response to the findings of the TWG, stating that they had given too much emphasis on the results from the Dubna group. Sony VAIO VPCCW1S1E/R Battery
In particular they pointed out that the Russian group had altered the details of their claims several times over a period of 20 years, a fact that the Russian team does not deny. They also stressed that the TWG had given too much credence to the chemistry experiments performed by the Russians and accused the TWG of not having appropriately qualified personnel on the committee.Sony VAIO VPCCW21FX/B Battery
The TWG responded by saying that this was not the case and having assessed each point raised by the American group said that they found no reason to alter their conclusion regarding priority of discovery. The IUPAC finally used the name suggested by the American team (rutherfordium) which may in some way reflect a change of opinion. Sony VAIO VPCCW21FX/R Battery
As a consequence of the initial competing claims of discovery, an element naming controversy arose. Since the Soviets claimed to have first detected the new element they suggested the name kurchatovium, Ku, in honor of Igor Kurchatov (1903–1960), former head of Soviet nuclear research. Sony VAIO VPCCW21FX/W Battery
This name had been used in books of the Soviet Bloc as the official name of the element. The Americans, however, proposed rutherfordium (Rf) for the new element to honor Ernest Rutherford, who is known as the "father" ofnuclear physics. Sony VAIO VPCCW26FX/B Battery
The International Union of Pure and Applied Chemistry (IUPAC) adopted unnilquadium, Unq, as a temporary, systematic element name, derived from the Latin names for digits 1, 0, and 4. In 1994, IUPAC suggested the name dubnium to be used since rutherfordium was suggested for element 106 and IUPAC felt that the Dubna team should be rightly recognized for their contributions. Sony VAIO VPCCW28EC Battery?Sony VAIO VPCCW28FJ/P Battery
However, there was still a dispute over the names of elements 104–107. In 1997 the teams involved resolved the dispute and adopted the current name rutherfordium. The name dubnium was given to element 105 at the same time. Sony VAIO VPCCW28FJ/R Battery
The chemical properties of rutherfordium were based on calculation which indicated that the relativistic effects on the electron shell might be strong enough that the p orbitals have a lower energy level than the d orbitals and therefore the element more behaves like lead. Sony VAIO VPCCW28FJ/W Battery
With better calculation methods and studies of the chemical properties of rutherfordium compounds it could be shown that rutherfordium behaves according to the rest of the group 4 elements.
Super-heavy elements such as rutherfordium are produced by bombarding lighter elements in particle accelerators that induces fusion reactions. Sony VAIO VPCCW29FJ/W Battery,Sony VAIO VPCCW2AFJ Battery
Whereas most of the isotopes of rutherfordium can be synthesized directly this way, some heavier ones have only been observed as decay products of elements with higher atomic numbers.
Depending on the energies involved, the former are separated into "hot" and "cold".Sony VAIO VPCCW2AHJ Battery
In hot fusion reactions, very light, high-energy projectiles are accelerated toward very heavy targets (actinides), giving rise to compound nuclei at high excitation energy (~40–50 MeV) that may either fission or evaporate several (3 to 5) neutrons. In cold fusion reactions, the produced fused nuclei have a relatively low excitation energy (~10–20 MeV), which decreases the probability that these products will undergo fission reactions. Sony VAIO VPCCW2S1E Battery
As the fused nuclei cool to the ground state, they require emission of only one or two neutrons, and thus, allows for the generation of more neutron-rich products. The latter is a distinct concept from that of where nuclear fusion claimed to be achieved at room temperature conditions (see cold fusion). Sony VAIO VPCCW2S1E/L Battery
Hot fusion studies
The synthesis of rutherfordium was first attempted in 1964 by the team at Dubna using the hot fusion reaction of neon-22 projectiles with plutonium-242 targets:
The first study produced evidence for a spontaneous fission with a 0.3 second half-life and another one at 8 seconds. Sony VAIO VPCCW2S1E/R Battery
While the former observation was eventually retracted, the latter eventually became associated with the 259Rf isotope. In 1966, the Soviet team repeated the experiment using a chemical study of volatile chloride products. They identified a volatile chloride with eka-hafnium properties that decayed fast through spontaneous fission. Sony VAIO VPCCW2S5C CN1 Battery?Sony VAIO VPCF112FX/B Battery
This gave strong evidence for the formation of RfCl4, and although a half-life was not accurately measured, later evidence suggested that the product was most likely 259Rf. The team repeated the experiment several times over the next few years, and in 1971, they revised the spontaneous fission half time for the isotope at 4.5 seconds. Sony VAIO VPCF115FG/B Battery,Sony VAIO VPCF116FGBI Battery
In 1969, researchers at the University of California led by Albert Ghiorso, tried to confirm the original results reported at Dubna. In a reaction of curium-248 withoxygen-16, they were unable to confirm the result of the Soviet team, but managed to observe the spontaneous fission of 260Rf with a very short half-life of 10–30 ms: Sony VAIO VPCF117FJ/W Battery?Sony VAIO VPCF117HG/BI Battery
In 1970, team also studied the same reaction with oxygen-18 and identified 261Rf with a half-life of 65 seconds (later refined to 75 seconds). Later experiments at the Lawrence Berkeley National Laboratory in California also revealed the formation of a short-lived isomer of 262Rf (which undergoes spontaneous fission with a half-life of 47 ms), and spontaneous fission activities with long lifetimes tentatively assigned to 263Rf. Sony VAIO VPCF118FJ/W Battery,Sony VAIO VPCF119FC Battery
Diagram of the experimental set-up used in the discovery of isotopes 257Rf and 259 Rf
The reaction of californium-249 with carbon-13 was also investigated by the Ghiorso team, which indicated the formation of the short-lived 258Rf (which undergoes spontaneous fission in 11 ms): Sony VAIO VPCF119FC/BI Battery?Sony VAIO VPCF119FJ/BI Battery
In trying to confirm these results by using carbon-12 instead, they also observed the first alpha decays from257Rf.
The reaction of berkelium-249 with nitrogen-14 was first studied in Dubna in 1977, and in 1985, researchers there confirmed the formation of the 260Rf isotope which quickly undergoes spontaneous fission in 28 ms: Sony VAIO VPCF11AFJ Battery,Sony VAIO VPCF11AGJ Battery
In 1996 the isotope 262Rf was observed in LBNL from the fusion of plutonium-244 with neon-22:
The team determined a half-life of 2.1 seconds, in contrast to earlier reports of 47 ms and suggested that the two half-lives might be due to different isomeric states of 262Rf. Sony VAIO VPCF11AHJ Battery
Studies on the same reaction by a team at Dubna, lead to the observation in 2000 of alpha decays from 261Rf and spontaneous fissions of 261mRf.
The hot fusion reaction using a uranium target was first reported at Dubna in 2000:
They observed decays from 260Rf and 259Rf, and later for 259Rf. In 2006, as part of their program on the study of uranium targets in hot fusion reactions, the team at LBNL also observed 261Rf. Sony VAIO VPCF11M1E Battery
Cold fusion studies
The first cold fusion experiments involving element 104 were done in 1974 at Dubna, by using light titanium-50 nuclei aimed at lead-208 isotope targets:
The measurement of a spontaneous fission activity was assigned to 256Rf, while later studies done at the Gesellschaft für Schwerionenforschung Institute (GSI), also measured decay properties for the isotopes 257Rf, and 255Rf. Sony VAIO VPCF11MFX/B Battery?Sony VAIO VPCF11S1E Battery
In 1974 researchers at Dubna investigated the reaction of lead-207 with titanium-50 to produce the isotope 255Rf. In a 1994 study at GSI using the lead-206 isotope, 255Rf as well as 254Rf were detected. 253Rf was similarly detected that year when lead-204 was used instead. Sony VAIO VPCF11S1E/B Battery
Most isotopes with an atomic mass below 262 have also observed as decay products of elements with a higher atomic number, allowing for refinement of their previously measured properties. Heavier isotopes of rutherfordium have only been observed as decay products. Sony VAIO VPCF11Z1E Battery
For example, a few alpha decay events terminating in 267Rf were observed in the decay chain of darmstadtium-279 since 2004:
This further underwent spontaneous fission with a half-time of about 1.3 h.
Investigations on the synthesis of the dubnium-263 isotope in 1999 at the University of Bern revealed events consistent with electron capture to form 263Rf. Sony VAIO VPCF11Z1E/BI Battery
A rutherfordium fraction was separated, and several spontaneous fission events with long lifetimes of about 15 minutes were observed, as well as and alpha decays with lifetimes of about 10 minutes. Reports on the decay chain of ununquadium-285 in 2010 showed five sequential alpha decays that terminate in 265Rf, which further undergoes spontaneous fission with a life-time of 152 seconds. Sony VAIO VPCF11ZHJ Battery,Sony VAIO VPCF127HGBI Battery
Some experimental evidence was obtained in 2004 for an even heavier isotope, 268Rf, in the decay chain of an isotope of ununpentium:
However, the last step in this chain was uncertain. After observing the five alpha decay events that generate dubnium-268, spontaneous fission events were observed with a long half-time. Sony VAIO VPCF137HG/BI Battery,Sony VAIO VPCS111FM/S Battery
It is unclear whether these events were due to direct spontaneous fission of 268Db, or 268Db produced electron capture events with long half-times to generate 268Rf. If the latter is produced and decays with a short life-time, the two possibilities cannot be distinguished. Sony VAIO VPCS115EC Battery
Given that the electron capture of 268Db cannot be detected, these spontaneous fission events may be due to 268Rf, in which case the half-life of this isotope cannot be extracted.
A 2007 report on the synthesis of ununtrium, the isotope 282113 was observed to undergo a similar decay to form 266Db, which undergoes spontaneous fission with a half-life of 22 minutes. Sony VAIO VPCS115FG Battery,Sony VAIO VPCS117GG Battery
Given that the electron capture of 266Db cannot be detected, these spontaneous fission events may be due to 266Rf, in which case the half-life of this isotope cannot be extracted.
Rutherfordium 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. Sony VAIO VPCS117GGB Battery?Sony VAIO VPCS118EC Battery
Fifteen different isotopes have been reported with atomic masses from 253 to 268 (with the exception of 264). Most of these decay predominantly through spontaneous fission pathways.
The lighter isotopes usually have shorter half-lives; Sony VAIO VPCS119FJ/B Battery
half-lives of under 50 ?s for 253Rf and 254Rf were observed. 256Rf, 258Rf, 260Rf are more stable at around 10 ms, 255Rf, 257Rf, 259Rf, and 262Rf live between 1 and 5 seconds, and 261Rf, 265Rf, and 263Rf are more stable, at around 1, 1.5, and 10 min, respectively. The heaviest isotopes are the most stable, with 267Rf having a measured half-life of about 1.3 h. Sony VAIO VPCS11AFJ Battery
The lightest isotopes were synthesized by direct fusion between two lighter nuclei and as decay products. The heaviest isotope produced by direct fusion is 262Rf; heavier isotopes have only been observed as decay products of elements with larger atomic numbers, of which only 267Rf has been confirmed. Sony VAIO VPCS11AGJ Battery
Isotopes 266Rf and268Rf may have also been observed as decay products and are thought to have long half-lives of 10 h and 6 h, respectively—but these have been measured indirectly, through systematic studies. While the isotopes 264Rf and 265Rf have yet to be observed, they are predicted to have long half-lives of 1 and 13h, respectively. Sony VAIO VPCS11AHJ Battery
In 1999, American scientists at the University of California, Berkeley, announced that they had succeeded in synthesizing three atoms of 293118. These parent nuclei were reported to have successively emitted seven alpha particles to form 265Rf nuclei, but their claim was retracted in 2001. Sony VAIO VPCS11AVJ Battery
Several early studies on the synthesis of 263Rf have indicated that this nuclide decays primarily by spontaneous fission with a half-life of 10–20 minutes. More recently, a study of hassium isotopes allowed the synthesis of atoms of 263Rf decaying with a shorter half-life of 8 seconds. Sony VAIO VPCS11J7E/B Battery
These two different decay modes must be associated with two isomeric states, but specific assignments are difficult due to the low number of observed events.
During research on the synthesis of rutherfordium isotopes utilizing the 244Pu(22Ne,5n)261Rf reaction, the product was found to undergo exclusive 8.28 MeV alpha decay with a half-life of 78 seconds. Sony VAIO VPCS11M1E/W Battery,Sony VAIO VPCS11V9E Battery
Later studies at GSI on the synthesis of copernicium and hassium isotopes produced conflicting data, as 261Rf produced in the decay chain was found to undergo 8.52 MeV alpha decay with a half-life of 4 seconds. Later results indicated a predominant fission branch. These contradictions led to some doubt on the discovery of copernicium. Sony VAIO VPCS11V9E/B Battery
The first isomer is currently denoted 261aRf whilst the second is denoted 261bRf. However, it is thought that the first nucleus belongs to a high-spin ground state and the latter to a low-spin metastable state. The discovery and confirmation of 261bRf provided proof for the discovery of copernicium in 1996. Sony VAIO VPCS11X9E/B Battery
A detailed spectroscopic study of the production of 257Rf nuclei using the reaction 208Pb(50Ti,n)257Rf allowed the identification of an isomeric level in 257Rf. The work confirmed that 257gRf has a complex spectrum with 15 alpha lines. A level structure diagram was calculated for both isomers. Similar isomers were reported for 256Rf also. Sony VAIO VPCS123FGB Battery