Element 1: Hydrogen (H), Other non-metal
Element 2: Helium (He), Noble gas
Element 3: Lithium (Li), Alkali metal
Element 4: Beryllium (Be), Alkaline earth metal
Element 5: Boron (B), Metalloid
Element 6: Carbon (C), Other non-metal
Element 7: Nitrogen (N), Other non-metal
Element 8: Oxygen (O), Other non-metal
Element 9: Fluorine (F), Halogen
Element 10: Neon (Ne), Noble gas
Element 11: Sodium (Na), Alkali metal
Element 12: Magnesium (Mg), Alkaline earth metal
Element 13: Aluminium (Al), Other metal
Element 14: Silicon (Si), Metalloid
Element 15: Phosphorus (P), Other non-metal
Element 16: Sulfur (S), Other non-metal
Element 17: Chlorine (Cl), Halogen
Element 18: Argon (Ar), Noble gas
Element 19: Potassium (K), Alkali metal
Element 20: Calcium (Ca), Alkaline earth metal
Element 21: Scandium (Sc), Transition metal
Element 22: Titanium (Ti), Transition metal
Element 23: Vanadium (V), Transition metal
Element 24: Chromium (Cr), Transition metal
Element 25: Manganese (Mn), Transition metal
Element 26: Iron (Fe), Transition metal
Element 27: Cobalt (Co), Transition metal
Element 28: Nickel (Ni), Transition metal
Element 29: Copper (Cu), Transition metal
Element 30: Zinc (Zn), Transition metal
Element 31: Gallium (Ga), Other metal
Element 32: Germanium (Ge), Metalloid
Element 33: Arsenic (As), Metalloid
Element 34: Selenium (Se), Other non-metal
Element 35: Bromine (Br), Halogen
Element 36: Krypton (Kr), Noble gas
Element 37: Rubidium (Rb), Alkali metal
Element 38: Strontium (Sr), Alkaline earth metal
Element 39: Yttrium (Y), Transition metal
Element 40: Zirconium (Zr), Transition metal
Element 41: Niobium (Nb), Transition metal
Element 42: Molybdenum (Mo), Transition metal
Element 43: Technetium (Tc), Transition metal
Element 44: Ruthenium (Ru), Transition metal
Element 45: Rhodium (Rh), Transition metal
Element 46: Palladium (Pd), Transition metal
Element 47: Silver (Ag), Transition metal
Element 48: Cadmium (Cd), Transition metal
Element 49: Indium (In), Other metal
Element 50: Tin (Sn), Other metal
Element 51: Antimony (Sb), Metalloid
Element 52: Tellurium (Te), Metalloid
Element 53: Iodine (I), Halogen
Element 54: Xenon (Xe), Noble gas
Element 55: Caesium (Cs), Alkali metal
Element 56: Barium (Ba), Alkaline earth metal
Element 57: Lanthanum (La), Lanthanoid
Element 58: Cerium (Ce), Lanthanoid
Element 59: Praseodymium (Pr), Lanthanoid
Element 60: Neodymium (Nd), Lanthanoid
Element 61: Promethium (Pm), Lanthanoid
Element 62: Samarium (Sm), Lanthanoid
Element 63: Europium (Eu), Lanthanoid
Element 64: Gadolinium (Gd), Lanthanoid
Element 65: Terbium (Tb), Lanthanoid
Element 66: Dysprosium (Dy), Lanthanoid
Element 67: Holmium (Ho), Lanthanoid
Element 68: Erbium (Er), Lanthanoid
Element 69: Thulium (Tm), Lanthanoid
Element 70: Ytterbium (Yb), Lanthanoid
Element 71: Lutetium (Lu), Lanthanoid
Element 72: Hafnium (Hf), Transition metal
Element 73: Tantalum (Ta), Transition metal
Element 74: Tungsten (W), Transition metal
Element 75: Rhenium (Re), Transition metal
Element 76: Osmium (Os), Transition metal
Element 77: Iridium (Ir), Transition metal
Element 78: Platinum (Pt), Transition metal
Element 79: Gold (Au), Transition metal
Element 80: Mercury (Hg), Transition metal
Element 81: Thallium (Tl), Other metal
Element 82: Lead (Pb), Other metal
Element 83: Bismuth (Bi), Other metal
Element 84: Polonium (Po), Metalloid
Element 85: Astatine (At), Halogen
Element 86: Radon (Rn), Noble gas
Element 87: Francium (Fr), Alkali metal
Element 88: Radium (Ra), Alkaline earth metal
Element 89: Actinium (Ac), Actinoid
Element 90: Thorium (Th), Actinoid
Element 91: Protactinium (Pa), Actinoid
Element 92: Uranium (U), Actinoid
Element 93: Neptunium (Np), Actinoid
Element 94: Plutonium (Pu), Actinoid
Element 95: Americium (Am), Actinoid
Element 96: Curium (Cm), Actinoid
Element 97: Berkelium (Bk), Actinoid
Element 98: Californium (Cf), Actinoid
Element 99: Einsteinium (Es), Actinoid
Element 100: Fermium (Fm), Actinoid
Element 101: Mendelevium (Md), Actinoid
Element 102: Nobelium (No), Actinoid
Element 103: Lawrencium (Lr), Actinoid
Element 104: Rutherfordium (Rf), Transition metal
Element 105: Dubnium (Db), Transition metal
Element 106: Seaborgium (Sg), Transition metal
Element 107: Bohrium (Bh), Transition metal
Element 108: Hassium (Hs), Transition metal
Element 109: Meitnerium (Mt)
Element 110: Darmstadtium (Ds)
Element 111: Roentgenium (Rg)
Element 112: Copernicium (Cn), Transition metal
Element 113: Ununtrium (Uut)
Element 114: Ununquadium (Uuq)
Element 115: Ununpentium (Uup)
Element 116: Ununhexium (Uuh)
Element 117: Ununseptium (Uus)
Element 118: Ununoctium (Uuo)
General properties
Name, symbol, number nobelium, No, 102
Pronunciation /nˈbɛliəm/ noh-bel-ee-əm
or /nˈbliəm/ noh-bee-lee-əm
Element category actinide
Group, period, block n/a, 7, f
Standard atomic weight [259]
Electron configuration [Rn] 5f14 7s2
Electrons per shell 2, 8, 18, 32, 32, 8, 2 (Image)
Physical properties
Phase solid
Atomic properties
Oxidation states 2, 3
Ionization energies 1st: 641.6 kJ·mol−1
2nd: 1254.3 kJ·mol−1
3rd: 2605.1 kJ·mol−1
CAS registry number 10028-14-5
Most stable isotopes
Main article: Isotopes of nobelium
iso NA half-life DM DE (MeV) DP
262No syn 5 ms SF
260No syn 106 ms SF
259No syn 58m 75% α 7.69,7.61,7.53.... 255Fm
25% ε 259Md
258No syn 1.2 ms SF
257No syn 25 s α 8.32,8.22 253Fm
256No syn 2.91 s 99.5% α 8.45,8.40 252Fm
0.5% f
255No syn 3.1 m 61% α 8.12,8.08,7.93 251Fm
39% ε 2.012 255Md
254Nom2 syn 198 µs γ 254Nom1
254Nom1 syn 275 ms γ 250Nog
254Nog syn 51 s
253Nom syn 43.5 µs γ 253Nog
253No syn 1.62 m α 8.14,8.06,8.04,8.01 249Fm
252Nom syn 110 ms
252Nog syn 2.44 s 75% α 8.42,8.37 248Fm
25% SF
251No syn 0.76 s α 8.62,8.58 247Fm
250Nom syn 43 µs SF
250Nog syn 3.7 µs SF
v ·
Common English pronunciation of nobelium

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Nobelium (play /nˈbɛliəm/ noh-bel-ee-əm or /nˈbliəm/ noh-bee-lee-əm) is a synthetic element with the symbol No and atomic number 102. 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.


Discovery profile

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. 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. 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 250Fm, supposedly the daughter of 254102, which had an apparent half-life of ~3 s. 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.

+ 12
+ 4 1

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.

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.

+ 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.

Later work in 1967 at Berkeley and 1971 at Oak Ridge fully confirmed the discovery of element 102 and clarified earlier observations.

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.


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.

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.[citation needed]

Physical properties

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. However, the 1st, 2nd and 3rd ionization energies have been measured[citation needed]. In addition, an electronegativity value of 1.3 is also sometimes quoted. This is most definitely only an estimate since a true value can only be determined using a chemical compound of the element and no such compounds exist for nobelium.

Experimental chemistry

Aqueous phase chemistry

First experiments involving nobelium assumed that it predominantly formed a +III state like earlier actinoids. However, it was later found that nobelium forms a stable +II state in solution, although it can be oxidised to an oxidising +III state.[1] 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.

Summary of compounds and (complex) ions

Formula Names(s)
[No(H2O)6]3+ hexaaquanobelium(III)
[No(H2O)6]2+ hexaaquanobelium(II)


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.

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:

Evaporation Residue Observed No isotope
262Lr 262No
269Hs, 265Sg, 261Rf 257No
267Hs, 263Sg, 259Rf 255No
254Lr 254No
261Sg, 257Rf 253No
264Hs, 260Sg, 256Rf 252No
255Rf 251No

Chronology of isotope discovery

Isotope Year discovered Discovery reaction
250Nom 2001 204Pb(48Ca,2n)
250Nog 2006 204Pb(48Ca,2n)
251No 1967 244Cm(12C,5n)
252Nog 1959 244Cm(12C,4n)
252Nom ~2002 206Pb(48Ca,2n)
253Nog 1967 242Pu(16O,5n),239Pu(18O,4n)
253Nom 1971 249Cf(12C,4n)
254Nog 1966 243Am(15N,4n)
254Nom1 1967? 246Cm(13C,5n),246Cm(12C,4n)
254Nom2 ~2003 208Pb(48Ca,2n)
255No 1967 246Cm(13C,4n),248Cm(12C,5n)
256No 1967 248Cm(12C,4n),248Cm(13C,5n)
257No 1961? , 1967 248Cm(13C,4n)
258No 1967 248Cm(13C,3n)
259No 1973 248Cm(18O,α3n)
260No  ? 254Es + 22Ne,18O,13C - transfer
261No unknown
262No 1988 254Es + 22Ne - transfer (EC of 262Lr)

Isomerism in nobelium nuclides

254No The study of K-isomerism was recently studied by physicists at the University of Jyväskylä physics laboratory (JYFL). 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. 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. 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.

Chemical yields of isotopes

Cold fusion

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.

Projectile Target CN 1n 2n 3n 4n
48Ca 208Pb 256No 254No: 2050 nb ; 22.3 MeV
48Ca 207Pb 255No 253No: 1310 nb ; 22.4 MeV
48Ca 206Pb 254No 253No: 58 nb ; 23.6 MeV 252No: 515 nb ; 23.3 MeV 251No: 30 nb ; 30.7 MeV 250No: 260 pb ; 43.9 MeV
48Ca 204Pb 252No 250No:13.2 nb ; 23.2 MeV

Hot fusion

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.

Projectile Target CN 3n 4n 5n 6n
26Mg 232Th 258No 254No:1.6 nb 253No:9 nb 252No:8 nb
22Ne 238U 260No 256No:40 nb 255No:200 nb 254No:15 nb
22Ne 236U 258No 254No:7 nb 253No:25 nb 252No:15 nb

Retracted isotopes

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.


  1. ^ Toyoshima, A.; Kasamatsu, Y.; Tsukada, K.; Asai, M.; Kitatsuji, Y.; Ishii, Y.; Toume, H.; Nishinaka, I. et al. (Jul 2009). "Oxidation of Element 102, Nobelium, with Flow Electrolytic Column Chromatography on an Atom-at-a-Time Scale". Journal of the American Chemical Society 131 (26): 090610145759060. doi:10.1021/ja9030038. ISSN 0002-7863. PMID 19514720.  edit


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