Nobelium is a synthetic chemical element with the 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 the 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.

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Atomic properties

Atomic mass(259 u)

Atomic shell

Electron configurationRn 5f14 7s2
Ionization energy(1st) (6.62621 eV)
(2nd) (12.93 eV)
(3rd) (25.8 eV)
(4th) (41.5 eV)
(5th) (60 eV)
Shell model

Physical properties



Melting point(1,100 K)

Heat and conductivity

Thermal conductivity(10 W·m-1·K-1)



Chemical properties

Oxidation state+2 +3


Pauling scale1.3
Allred-Rochow scale1.2
Nagle scale1.18

Other properties

Natural occurrencesynthetic
Crystal structureFace-centered cubic
Goldschmidt Classificationsynthetic
Superconductorwithout transition tempperature
Radioactivityhighly radioactive