Nobelium is a synthetic chemical element with symbol No and atomic number 102. It is named in honor of Alfred Nobel, the inventor of dynamite and benefactor of science. A radioactive metal, it is the tenth transuranic element and is the penultimate member of the actinide series. Like all elements with atomic number over 100, nobelium can only be produced in particle accelerators by bombarding lighter elements with charged particles. A total of twelve nobelium isotopes are known to exist; the most stable is 259No with a half-life of 58 minutes, but the shorter-lived 255No (half-life 3.1 minutes) is most commonly used in chemistry because it can be produced on a larger scale.

Chemistry experiments have confirmed that nobelium behaves as a heavier homolog to ytterbium in the periodic table. The chemical properties of nobelium are not completely known: they are mostly only known in aqueous solution. Before nobelium's discovery, it was predicted that it would show a stable +2 oxidation state as well as the +3 state characteristic of the other actinides: these predictions were later confirmed, as the +2 state is much more stable than the +3 state in aqueous solution and it is difficult to keep nobelium in the +3 state.

In the 1950s and 1960s, many claims of the discovery of nobelium were made from laboratories in Sweden, the Soviet Union, and the United States. Although the Swedish scientists soon retracted their claims, 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) credited the Soviet team with the discovery, but retained nobelium, the Swedish proposal, as the name of the element due to its long-standing use in the literature.

Nobelium,  102No
  • /noʊˈbɛliəm/ (listen)
  • /noʊˈbiːliəm/
Mass number259 (most stable isotope)
Nobelium 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


Atomic number (Z)102
Groupgroup n/a
Periodperiod 7
Element category  actinide
Electron configuration[Rn] 5f14 7s2
Electrons per shell
2, 8, 18, 32, 32, 8, 2
Physical properties
Phase at STPunknown phase (predicted)[1]
Melting point1100 K ​(827 °C, ​1521 °F) (predicted)[1]
Density (near r.t.)9.9(4) g/cm3 (predicted)[2]
Atomic properties
Oxidation states+2, +3
ElectronegativityPauling scale: 1.3 (predicted)[3]
Ionization energies
  • 1st: 641.6 kJ/mol
  • 2nd: 1254.3 kJ/mol
  • 3rd: 2605.1 kJ/mol
  • (all estimated)
Other properties
Natural occurrencesynthetic
Crystal structureface-centered cubic (fcc)
Face-centered cubic crystal structure for nobelium

CAS Number10028-14-5
Namingafter Alfred Nobel
DiscoveryJoint Institute for Nuclear Research (1966)
Main isotopes of nobelium
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
253No syn 1.6 min 80% α 249Fm
20% β+ 253Md
254No syn 51 s 90% α 250Fm
10% β+ 254Md
255No syn 3.1 min 61% α 251Fm
39% β+ 255Md
257No syn 25 s 99% α 253Fm
1% β+ 257Md
259No syn 58 min 75% α 255Fm
25% ε 259Md
<10% SF


The element was named after Alfred Nobel.

The discovery of element 102 was a complicated process and was claimed by groups from Sweden, the United States, and the Soviet Union. The first complete and incontrovertible report of its detection only came in 1966 from the Joint Institute of Nuclear Research at Dubna (then in the Soviet Union).[4]

The first announcement of the discovery of element 102 was announced by physicists at the Nobel Institute in Sweden in 1957. The team reported that they had bombarded a curium target with carbon-13 ions for twenty-five hours in half-hour intervals. Between bombardments, ion-exchange chemistry was performed on the target. Twelve out of the fifty bombardments contained samples emitting (8.5 ± 0.1) MeV alpha particles, which were in drops which eluted earlier than fermium (atomic number Z = 100) and californium (Z = 98). The half-life reported was 10 minutes and was assigned to either 251102 or 253102, although the possibility that the alpha particles observed were from a presumably short-lived mendelevium (Z = 101) isotope created from the electron capture of element 102 was not excluded.[4] The team proposed the name nobelium (No) for the new element,[5][6] which was immediately approved by IUPAC,[7] a decision which the Dubna group characterized in 1968 as being hasty.[8] The following year, scientists at the Lawrence Berkeley National Laboratory repeated the experiment but were unable to find any 8.5 MeV events which were not background effects.[4]

In 1959, the Swedish team attempted to explain the Berkeley team's inability to detect element 102 in 1958, maintaining that they did discover it. However, later work has shown that no nobelium isotopes lighter than 259No (no heavier isotopes could have been produced in the Swedish experiments) with a half-life over 3 minutes exist, and that the Swedish team's results are most likely from thorium-225, which has a half-life of 8 minutes and quickly undergoes triple alpha decay to polonium-213, which has a decay energy of 8.53612 MeV. This hypothesis is lent weight by the fact that thorium-225 can easily be produced in the reaction used and would not be separated out by the chemical methods used. Later work on nobelium also showed that the divalent state is more stable than the trivalent one and hence that the samples emitting the alpha particles could not have contained nobelium, as the divalent nobelium would not have eluted with the other trivalent actinides.[4] Thus, the Swedish team later retracted their claim and associated the activity to background effects.[7]

The Berkeley team, consisting of Albert Ghiorso, Glenn T. Seaborg, John R. Walton and Torbjørn Sikkeland, then claimed the synthesis of element 102 in 1958. The team used the new heavy-ion linear accelerator (HILAC) to bombard a curium target (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 fermium-250, supposedly the daughter of 254102 (produced from the curium-246), which had an apparent half-life of ~3 s. Later 1963 Dubna work confirmed that 254102 could be produced in this reaction, but that its half-life was actually 50±10 s. In 1967, the Berkeley team attempted to defend their work, stating that the isotope found was indeed 250Fm but the isotope that the half-life measurements actually related to was californium-244, granddaughter of 252102, produced from the more abundant curium-244. Energy differences were then attributed to "resolution and drift problems", although these had not been previously reported and should also have influenced other results. 1977 experiments showed that 252102 indeed had a 2.3-second half-life. However, 1973 work also showed that the 250Fm recoil could have also easily been produced from the isomeric transition of 250mFm (half-life 1.8 s) which could also have been formed in the reaction at the energy used.[4] Given this, it is probable that no nobelium was actually produced in this experiment.[4]

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 254102 but later changed to 252102. However, they also noted that it was not certain that nobelium had been produced due to difficult conditions.[4] The Berkeley team decided to adopt the proposed name of the Swedish team, "nobelium", for the element.[7]

+ 12
+ 4 1


Meanwhile, in Dubna, experiments were carried out in 1958 and 1960 aiming to synthesize element 102 as well. The first 1958 experiment bombarded plutonium-239 and -241 with oxygen-16 ions. Some alpha decays with energies just over 8.5 MeV were observed, and they were assigned to 251,252,253102, although the team wrote that formation of isotopes from lead or bismuth impurities (which would not produce nobelium) could not be ruled out. While later 1958 experiments noted that new isotopes could be produced from mercury, thallium, lead, or bismuth impurities, the scientists still stood by their conclusion that element 102 could be produced from this reaction, mentioning a half-life of under 30 seconds and a decay energy of (8.8 ± 0.5) MeV. Later 1960 experiments proved that these were background effects. 1967 experiments also lowered the decay energy to (8.6 ± 0.4) MeV, but both values are too high to possibly match those of 253No or 254No.[4] The Dubna team later stated in 1970 and again in 1987 that these results were not conclusive.[4]

In 1961, Berkeley scientists claimed the discovery of element 103 in the reaction of californium with boron and carbon ions. They claimed the production of the isotope 257103, and also claimed to have synthesized an alpha decaying isotope of element 102 that had a half-life of 15 s and alpha decay energy 8.2 MeV. They assigned this to 255102 without giving a reason for the assignment. The values do not agree with those now known for 255No, although they do agree with those now known for 257No, and while this isotope probably played a part in this experiment its discovery was inconclusive.[4]

Work on element 102 also continued in Dubna, and in 1964, experiments were carried out there to detect alpha-decay daughters of element 102 isotopes by synthesizing element 102 from the reaction of a uranium-238 target with neon ions. The products were carried along a silver catcher foil and purified chemically, and the isotopes 250Fm and 252Fm were detected. The yield of 252Fm was interpreted as evidence that its parent 256102 was also synthesized: as it was noted that 252Fm could also be produced directly in this reaction by the simultaneous emission of an alpha particle with the excess neutrons, steps were taken to ensure that 252Fm could not go directly to the catcher foil. The half-life detected for 256102 was 8 s, which is much higher than the more modern 1967 value of (3.2 ± 0.2) s.[4] Further experiments were conducted in 1966 for 254102, using the reactions 243Am(15N,4n)254102 and 238U(22Ne,6n)254102, finding a half-life of (50 ± 10) s: at that time the discrepancy between this value and the earlier Berkeley value was not understood, although later work proved that the formation of the isomer 250mFm was less likely in the Dubna experiments than at the Berkeley ones. In hindsight, the Dubna results on 254102 were probably correct and can be now considered a conclusive detection of element 102.[4]

One more very convincing experiment from Dubna was published in 1966, again using the same two reactions, which concluded that 254102 indeed had a half-life much longer than the 3 seconds claimed by Berkeley.[4] Later work in 1967 at Berkeley and 1971 at the Oak Ridge National Laboratory fully confirmed the discovery of element 102 and clarified earlier observations.[7] In December 1966, the Berkeley group repeated the Dubna experiments and fully confirmed them, and used this data to finally assign correctly the isotopes they had previously synthesized but could not yet identify at the time, and thus claimed to have discovered nobelium in 1958 to 1961.[7]

+ 22
+ 6 1


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 after Irène Joliot-Curie, who had recently died, creating an element naming controversy that would not be resolved for several decades, which each group using its own proposed names.[7]

In 1992, the IUPAC-IUPAP Transfermium Working Group (TWG) reassessed the claims of discovery and concluded that only the Dubna work from 1966 correctly detected and assigned decays to nuclei with atomic number 102 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.[4] This decision was criticized by Berkeley the following year, calling the reopening of the cases of elements 101 to 103 a "futile waste of time", while Dubna agreed with IUPAC's decision.[8]

In 1994, as part of an attempted resolution to the element naming controversy, IUPAC ratified names for elements 101–109. For element 102, it ratified the name nobelium (No) 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.[9] Because of outcry over the 1994 names, which mostly did not respect the choices of the discoverers, a comment period ensued, and in 1995 IUPAC named element 102 flerovium (Fl) as part of a new proposal, after either Georgy Flyorov or his eponymous Flerov Laboratory of Nuclear Reactions.[10] This proposal was also not accepted, and in 1997 the name "nobelium" was restored.[9] Today the name "flerovium", with the same symbol, refers to element 114.[11]



Fblock fd promotion energy
Energy required to promote an f electron to the d subshell for the f-block lanthanides and actinides. Above around 210 kJ/mol, this energy is too high to be provided for by the greater crystal energy of the trivalent state and thus einsteinium, fermium, and mendelevium form divalent metals like the lanthanides europium and ytterbium. Nobelium is also expected to form a divalent metal, but this has not yet been confirmed.[12]

In the periodic table, nobelium is located to the right of the actinide mendelevium, to the left of the actinide lawrencium, and below the lanthanide ytterbium. Nobelium metal has not yet been prepared in bulk quantities, and bulk preparation is currently impossible.[13] Nevertheless, a number of predictions and some preliminary experimental results have been done regarding its properties.[13]

The lanthanides and actinides, in the metallic state, can exist as either divalent (such as europium and ytterbium) or trivalent (most other lanthanides) metals. The former have fn+1s2 configurations, whereas the latter have fnd1s2 configurations. In 1975, Johansson and Rosengren examined the measured and predicted values for the cohesive energies (enthalpies of crystallization) of the metallic lanthanides and actinides, both as divalent and trivalent metals.[14][15] The conclusion was that the increased binding energy of the [Rn]5f136d17s2 configuration over the [Rn]5f147s2 configuration for nobelium was not enough to compensate for the energy needed to promote one 5f electron to 6d, as is true also for the very late actinides: thus einsteinium, fermium, mendelevium, and nobelium were expected to be divalent metals, although for nobelium this prediction has not yet been confirmed.[14] The increasing predominance of the divalent state well before the actinide series concludes is attributed to the relativistic stabilization of the 5f electrons, which increases with increasing atomic number: an effect of this is that nobelium is predominantly divalent instead of trivalent, unlike all the other lanthanides and actinides.[16] In 1986, nobelium metal was estimated to have an enthalpy of sublimation between 126 kJ/mol, a value close to the values for einsteinium, fermium, and mendelevium and supporting the theory that nobelium would form a divalent metal.[13] Like the other divalent late actinides (except the once again trivalent lawrencium), metallic nobelium should assume a face-centered cubic crystal structure.[2] Divalent nobelium metal should have a metallic radius of around 197 pm.[13] Nobelium's melting point has been predicted to be 827 °C, the same value as that estimated for the neighboring element mendelevium.[17] Its density is predicted to be around 9.9 ± 0.4 g/cm3.[2]


The chemistry of nobelium is incompletely characterized and is known only in aqueous solution, in which it can take on the +3 or +2 oxidation states, the latter being more stable.[5] It was largely expected before the discovery of nobelium that in solution, it would behave like the other actinides, with the trivalent state being predominant; however, Seaborg predicted in 1949 that the +2 state would also be relatively stable for nobelium, as the No2+ ion would have the ground-state electron configuration [Rn]5f14, including the stable filled 5f14 shell. It took nineteen years before this prediction was confirmed.[18]

In 1967, experiments were conducted to compare nobelium's chemical behavior to that of terbium, californium, and fermium. All four elements were reacted with chlorine and the resulting chlorides were deposited along a tube, along which they were carried by a gas. It was found that the nobelium chloride produced was strongly adsorbed on solid surfaces, proving that it was not very volatile, like the chlorides of the other three investigated elements. However, both NoCl2 and NoCl3 were expected to exhibit nonvolatile behavior and hence this experiment was inconclusive as to what the preferred oxidation state of nobelium was.[18] Determination of nobelium's favoring of the +2 state had to wait until the next year, when cation-exchange chromatography and coprecipitation experiments were carried out on around fifty thousand 255No atoms, finding that it behaved differently from the other actinides and more like the divalent alkaline earth metals. This proved that in aqueous solution, nobelium is most stable in the divalent state when strong oxidizers are absent.[18] Later experimentation in 1974 showed that nobelium eluted with the alkaline earth metals, between Ca2+ and Sr2+.[18] Nobelium is the only f-block element for which the +2 state is the most common and stable one in aqueous solution. This occurs because of the large energy gap between the 5f and 6d orbitals at the end of the actinide series.[19]

The relativistic stability of the 7s subshell greatly destabilizes nobelium dihydride, NoH2, and relativistic stabilisation of the 7p1/2 spinor over the 6d3/2 spinor mean that excited states in nobelium atoms have 7s and 7p contribution instead of the expected 6d contribution. The long No–H distances in the NoH2 molecule and the significant charge transfer lead to extreme ionicity with a dipole moment of 5.94 D for this molecule. In this molecule, nobelium is expected to exhibit main-group-like behavior, specifically acting like an alkaline earth metal with its ns2 valence shell configuration and core-like 5f orbitals.[20]

Nobelium's complexing ability with chloride ions is most similar to that of barium, which complexes rather weakly.[18] Its complexing ability with citrate, oxalate, and acetate in an aqueous solution of 0.5 M ammonium nitrate is between that of calcium and strontium, although it is somewhat closer to that of strontium.[18]

The standard reduction potential of the E°(No3+→No2+) couple was estimated in 1967 to be between +1.4 and +1.5 V;[18] it was later found in 2009 to be only about +0.75 V.[21] The positive value shows that No2+ is more stable than No3+ and that No3+ is a good oxidizing agent. While the quoted values for the E°(No2+→No0) and E°(No3+→No0) vary among sources, the accepted standard estimates are −2.61 and −1.26 V.[18] It has been predicted that the value for the E°(No4+→No3+) couple would be +6.5 V.[18] The Gibbs energies of formation for No3+ and No2+ are estimated to be −342 and −480 kJ/mol, respectively.[18]


A nobelium atom has 102 electrons, of which three can act as valence electrons. They are expected to be arranged in the configuration [Rn]5f147s2 (ground state term symbol 1S0), although experimental verification of this electron configuration had not yet been made as of 2006.[13] In forming compounds, all the three valence electrons may be lost, leaving behind a [Rn]5f13 core: this conforms to the trend set by the other actinides with their [Rn]5fn electron configurations in the tripositive state. Nevertheless, it is more likely that only two valence electrons may be lost, leaving behind a stable [Rn]5f14 core with a filled 5f14 shell. The first ionization potential of nobelium was measured to be at most (6.65 ± 0.07) eV in 1974, based on the assumption that the 7s electrons would ionize before the 5f ones;[22] this value has since not yet been refined further due to nobelium's scarcity and high radioactivity.[23] The ionic radius of hexacoordinate and octacoordinate No3+ had been preliminarily estimated in 1978 to be around 90 and 102 pm respectively;[18] the ionic radius of No2+ has been experimentally found to be 100 pm to two significant figures.[13] The enthalpy of hydration of No2+ has been calculated as 1486 kJ/mol.[18]


Twelve isotopes of nobelium are known, with mass numbers 250–260 and 262; all are radioactive.[24] Additionally, nuclear isomers are known for mass numbers 251, 253, and 254.[25][26] Of these, the longest-lived isotope is 259No with a half-life of 58 minutes, and the longest-lived isomer is 251mNo with a half-life of 1.7 seconds.[25][26] However, the still undiscovered isotope 261No is predicted to have a still longer half-life of 170 min.[25][26] Additionally, the shorter-lived 255No (half-life 3.1 minutes) is more often used in chemical experimentation because it can be produced in larger quantities from irradiation of californium-249 with carbon-12 ions.[24] After 259No and 255No, the next most stable nobelium isotopes are 253No (half-life 1.62 minutes), 254No (51 seconds), 257No (25 seconds), 256No (2.91 seconds), and 252No (2.57 seconds).[24][25][26] All of the remaining nobelium isotopes have half-lives that are less than a second, and the shortest-lived known nobelium isotope (250No) has a half-life of only 0.25 milliseconds.[24][25][26] The isotope 254No is especially interesting theoretically as it is in the middle of a series of prolate nuclei from 231Pa to 279Rg, and the formation of its nuclear isomers (of which two are known) is controlled by proton orbitals such as 2f5/2 which come just above the spherical proton shell; it can be synthesized in the reaction of 208Pb with 48Ca.[27]

The half-lives of nobelium isotopes increase smoothly from 250No to 253No. However, a dip appears at 254No, and beyond this the half-lives of even-even nobelium isotopes drop sharply as spontaneous fission becomes the dominant decay mode. For example, the half-life of 256No is almost three seconds, but that of 258No is only 1.2 milliseconds.[24][25][26] This shows that at nobelium, the mutual repulsion of protons poses a limit to the region of long-lived nuclei in the actinide series.[28] The even-odd nobelium isotopes mostly continue to have longer half-lives as their mass numbers increase, with a dip in the trend at 257No.[24][25][26]

Preparation and purification

The isotopes of nobelium are mostly produced by bombarding actinide targets (uranium, plutonium, curium, californium, or einsteinium), with the exception of nobelium-262, which is produced as the daughter of lawrencium-262.[24] The most commonly used isotope, 255No, can be produced from bombarding curium-248 or californium-249 with carbon-12: the latter method is more common. Irradiating a 350 μg cm−2 target of californium-249 with three trillion (3 × 1012) 73 MeV carbon-12 ions per second for ten minutes can produce around 1200 nobelium-255 atoms.[24]

Once the nobelium-255 is produced, it can be separated out in a similar way as used to purify the neighboring actinide mendelevium. The recoil momentum of the produced nobelium-255 atoms is used to bring them physically far away from the target from which they are produced, bringing them onto a thin foil of metal (usually beryllium, aluminium, platinum, or gold) just behind the target in a vacuum: this is usually combined by trapping the nobelium atoms in a gas atmosphere (frequently helium), and carrying them along with a gas jet from a small opening in the reaction chamber. Using a long capillary tube, and including potassium chloride aerosols in the helium gas, the nobelium atoms can be transported over tens of meters.[29] The thin layer of nobelium collected on the foil can then be removed with dilute acid without completely dissolving the foil.[29] The nobelium can then be isolated by exploiting its tendency to form the divalent state, unlike the other trivalent actinides: under typically used elution conditions (bis-(2-ethylhexyl) phosphoric acid (HDEHP) as stationary organic phase and 0.05 M hydrochloric acid as mobile aqueous phase, or using 3 M hydrochloric acid as an eluant from cation-exchange resin columns), nobelium will pass through the column and elute while the other trivalent actinides remain on the column.[29] However, if a direct "catcher" gold foil is used, the process is complicated by the need to separate out the gold using anion-exchange chromatography before isolating the nobelium by elution from chromatographic extraction columns using HDEHP.[29]


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  22. ^ Martin, William C.; Hagan, Lucy; Reader, Joseph; Sugar, Jack (1974). "Ground Levels and Ionization Potentials for Lanthanide and Actinide Atoms and Ions". Journal of Physical and Chemical Reference Data. 3 (3): 771–9. Bibcode:1974JPCRD...3..771M. doi:10.1063/1.3253147.
  23. ^ Lide, David R. (editor), CRC Handbook of Chemistry and Physics, 84th Edition, CRC Press, Boca Raton (FL), 2003, section 10, Atomic, Molecular, and Optical Physics; Ionization Potentials of Atoms and Atomic Ions
  24. ^ a b c d e f g h Silva, pp. 1637–8
  25. ^ a b c d e f g "Nucleonica :: Web driven nuclear science".
  26. ^ a b c d e f g Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
  27. ^ Kratz, Jens Volker (5 September 2011). The Impact of Superheavy Elements on the Chemical and Physical Sciences (PDF). 4th International Conference on the Chemistry and Physics of the Transactinide Elements. Retrieved 27 August 2013.
  28. ^ Nurmia, Matti (2003). "Nobelium". Chemical and Engineering News. 81 (36).
  29. ^ a b c d Silva, pp. 1638–9


  • Silva, Robert J. (2011). "Chapter 13. Fermium, Mendelevium, Nobelium, and Lawrencium". In Morss, Lester R.; Edelstein, Norman M.; Fuger, Jean. The Chemistry of the Actinide and Transactinide Elements. Netherlands: Springer. pp. 1621–1651. doi:10.1007/978-94-007-0211-0_13. ISBN 978-94-007-0210-3.

External links


The actinide or actinoid (IUPAC nomenclature) series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium.Strictly speaking, both actinium and lawrencium have been labeled as group 3 elements, but both elements are often included in any general discussion of the chemistry of the actinide elements. Actinium is the more often omitted of the two, because its placement as a group 3 element is somewhat more common in texts and for semantic reasons: since "actinide" means "like actinium", it has been argued that actinium cannot logically be an actinide, but IUPAC acknowledges its inclusion based on common usage.The actinide series derives its name from the first element in the series, actinium. The informal chemical symbol An is used in general discussions of actinide chemistry to refer to any actinide. All but one of the actinides are f-block elements, with the exception being either actinium or lawrencium. The series mostly corresponds to the filling of the 5f electron shell, although actinium and thorium lack any 5f electrons, and curium and lawrencium have the same number as the preceding element. In comparison with the lanthanides, also mostly f-block elements, the actinides show much more variable valence. They all have very large atomic and ionic radii and exhibit an unusually large range of physical properties. While actinium and the late actinides (from americium onwards) behave similarly to the lanthanides, the elements thorium, protactinium, and uranium are much more similar to transition metals in their chemistry, with neptunium and plutonium occupying an intermediate position.

All actinides are radioactive and release energy upon radioactive decay; naturally occurring uranium and thorium, and synthetically produced plutonium are the most abundant actinides on Earth. These are used in nuclear reactors and nuclear weapons. Uranium and thorium also have diverse current or historical uses, and americium is used in the ionization chambers of most modern smoke detectors.

Of the actinides, primordial thorium and uranium occur naturally in substantial quantities. The radioactive decay of uranium produces transient amounts of actinium and protactinium, and atoms of neptunium and plutonium are occasionally produced from transmutation reactions in uranium ores. The other actinides are purely synthetic elements. Nuclear weapons tests have released at least six actinides heavier than plutonium into the environment; analysis of debris from a 1952 hydrogen bomb explosion showed the presence of americium, curium, berkelium, californium, einsteinium and fermium.In presentations of the periodic table, the lanthanides and the actinides are customarily shown as two additional rows below the main body of the table, with placeholders or else a selected single element of each series (either lanthanum or lutetium, and either actinium or lawrencium, respectively) shown in a single cell of the main table, between barium and hafnium, and radium and rutherfordium, respectively. This convention is entirely a matter of aesthetics and formatting practicality; a rarely used wide-formatted periodic table inserts the lanthanide and actinide series in their proper places, as parts of the table's sixth and seventh rows (periods).

Alfred Nobel

Alfred Bernhard Nobel (; Swedish: [ˈalfrɛd nʊˈbɛlː] (listen); 21 October 1833 – 10 December 1896) was a Swedish businessman, chemist, engineer, inventor, and philanthropist.

Nobel held 355 different patents, dynamite being the most famous. The synthetic element nobelium was named after him.Known for inventing dynamite, Nobel also owned Bofors, which he had redirected from its previous role as primarily an iron and steel producer to a major manufacturer of cannon and other armaments.

After reading a premature obituary which condemned him for profiting from the sales of arms, he bequeathed his fortune to institute the Nobel Prizes.His name also survives in modern-day companies such as Dynamit Nobel and AkzoNobel, which are descendants of mergers with companies Nobel himself established.

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.

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 lawrencium

Lawrencium (103Lr) 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 258Lr in 1961. There are twelve known radioisotopes from 252Lr to 266Lr, and 1 isomer (253mLr). The longest-lived isotope is 266Lr with a half-life of 11 hours. Heavier isotopes are expected to have longer half-lives.

Isotopes of nobelium

Nobelium (102No) 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 (and correctly identified) was 254No in 1966. There are 12 known radioisotopes, which are 250No to 260No and 262No, and 3 isomers, 251mNo, 253mNo, and 254mNo. The longest-lived isotope is 259No with a half-life of 58 minutes. The longest-lived isomer is 251mNo with a half-life of 1.7 seconds.


Lawrencium is a synthetic chemical element with symbol Lr (formerly Lw) and atomic number 103. It is named in honor of Ernest Lawrence, inventor of the cyclotron, a device that was used to discover many artificial radioactive elements. A radioactive metal, lawrencium is the eleventh transuranic element and is also the final member of the actinide series. Like all elements with atomic number over 100, lawrencium can only be produced in particle accelerators by bombarding lighter elements with charged particles. Twelve isotopes of lawrencium are currently known; the most stable is 266Lr with a half-life of 11 hours, but the shorter-lived 260Lr (half-life 2.7 minutes) is most commonly used in chemistry because it can be produced on a larger scale.

Chemistry experiments have confirmed that lawrencium behaves as a heavier homolog to lutetium in the periodic table, and is a trivalent element. It thus could also be classified as the first of the 7th-period transition metals: however, its electron configuration is anomalous for its position in the periodic table, having an s2p configuration instead of the s2d configuration of its homolog lutetium. This means that lawrencium may be more volatile than expected for its position in the periodic table and have a volatility comparable to that of lead.

In the 1950s, 1960s, and 1970s, many claims of the synthesis of lawrencium of varying quality were made from laboratories in the Soviet Union and the United States. The priority of the discovery and therefore the naming of the element was disputed between Soviet and American scientists, and while the International Union of Pure and Applied Chemistry (IUPAC) initially established lawrencium as the official name for the element and gave the American team credit for the discovery, this was reevaluated in 1997, giving both teams shared credit for the discovery but not changing the element's name.

List of chemical elements naming controversies

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

List of radioactive isotopes by half-life

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

Major actinide

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


Mendelevium is a synthetic element with chemical symbol Md (formerly Mv) and atomic number 101. A metallic radioactive transuranic element in the actinide series, it is the first element that currently cannot be produced in macroscopic quantities through neutron bombardment of lighter elements. It is the third-to-last actinide and the ninth transuranic element. It can only be produced in particle accelerators by bombarding lighter elements with charged particles. A total of sixteen mendelevium isotopes are known, the most stable being 258Md with a half-life of 51 days; nevertheless, the shorter-lived 256Md (half-life 1.17 hours) is most commonly used in chemistry because it can be produced on a larger scale.

Mendelevium was discovered by bombarding einsteinium with alpha particles in 1955, the same method still used to produce it today. It was named after Dmitri Mendeleev, father of the periodic table of the chemical elements. Using available microgram quantities of the isotope einsteinium-253, over a million mendelevium atoms may be produced each hour. The chemistry of mendelevium is typical for the late actinides, with a preponderance of the +3 oxidation state but also an accessible +2 oxidation state. Owing to the small amounts of produced mendelevium and all of its isotopes having relatively short half-lives, there are currently no uses for it outside basic scientific research.


Nobel can mean:

Nobel Prize, awarded annually since 1901, from the bequest of Swedish inventor Alfred Nobel

The Nobel family:

Alfred Nobel, (1833-1896), the inventor of dynamite, instituted the Nobel Prizes

Immanuel Nobel, (1801-1872), father of Ludvig and Alfred Nobel

Robert Nobel, (1829-1896), brother of Alfred Nobel, pioneer of the oil industry

Ludvig Nobel, (1831-1888), brother of Alfred Nobel, founder of Branobel and its first president

Emil Oskar Nobel, (1843-1864), brother of Alfred Nobel

Emanuel Nobel, (1859-1932), son of Ludvig Nobel and Branobel's second president

Marta Helena Nobel-Oleinikoff, (1881-1973), daughter of Ludvig Nobel

Claes Nobel, great grandnephew of Alfred

Nobel (company), a telecommunications company founded in 1998 by Thomas Knobel

Branobel, or The Petroleum Production Company Nobel Brothers, Limited, an oil industry founded by Ludvig Nobel

Nobelite, an employee of the Nobel family's companies

Nobelium, a synthetic element with the symbol No and atomic number 102, named after Alfred Nobel

Nobel Industries (Scotland), a UK chemicals company founded by Alfred Nobel

Nobel Industries (Sweden) - UK chemicals company founded by Alfred Nobel, merged in 1994 with Akzo.

Nobel Biocare, a bio-tech company, formerly a subsidiary of Nobel Industries

Akzo Nobel, the result of the merger between Akzo and Nobel Industries in 1994

Nobel, Ontario, a village located in Ontario, Canada.

Nobel (crater), a crater on the far side of the Moon.

6032 Nobel, a main-belt asteroid.

Nobel (automobile) a licence-built version of the German Fuldamobil, manufactured in the UK and Chile.

The Nobel School, a Secondary School in Stevenage, England.

The Nobel Ice (Fabergé egg)

Nobel (typeface), a geometric, sans-serif typeface.

Nobel (TV series), a Norwegian television series around the country's military involvement in Afghanistan


Seaborgium is a synthetic chemical element with symbol Sg and atomic number 106. It is named after the American nuclear chemist Glenn T. Seaborg. As a synthetic element, it can be created in a laboratory but is not found in nature. It is also radioactive; the most stable known isotope, 269Sg, has a half-life of approximately 14 minutes.In the periodic table of the elements, it is a d-block transactinide element. It is a member of the 7th period and belongs to the group 6 elements as the fourth member of the 6d series of transition metals. Chemistry experiments have confirmed that seaborgium behaves as the heavier homologue to tungsten in group 6. The chemical properties of seaborgium are characterized only partly, but they compare well with the chemistry of the other group 6 elements.

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

Synthetic element

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

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

The Elements (song)

"The Elements" is a song by musical humorist and lecturer Tom Lehrer, which recites the names of all the chemical elements known at the time of writing, up to number 102, nobelium. It was written in 1959 and can be found on his albums Tom Lehrer in Concert, More of Tom Lehrer and An Evening Wasted with Tom Lehrer. The song is sung to the tune of the Major-General's Song from The Pirates of Penzance by Gilbert and Sullivan.The song is also included in the musical revue Tom Foolery, along with many of Lehrer's other songs.

Torbjørn Sikkeland

Torbjørn Sikkeland (3 August 1923 – 7 November 2014) was a Norwegian chemist, nuclear physicist and radiation biophysicist.

He was born in Varteig. He was part of the Berkeley team that claimed discovery of the transuranic elements of nobelium and lawrencium. He was appointed professor at the Norwegian Institute of Technology in Trondheim from 1969 to 1993. He was a fellow of the Norwegian Academy of Technological Sciences.He died in November 2014.

Transfermium Wars

The names for the chemical elements 104 to 106 were the subject of a major controversy starting in the 1960s, described by some nuclear chemists as the Transfermium Wars because it concerned the elements following fermium (element 100) on the periodic table.

This controversy arose from disputes between American scientists and Soviet scientists as to which had first isolated these elements. The final resolution of this controversy in 1997 also decided the names of elements 107 to 109.

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.

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