Nobelium
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.
Identity
- Atomic mass
- [259] u
- Category
- Actinides
- Group
- 3
- Period
- 7
- Block
- f
- Oxidation States
- +2, +3
- Phase (25 °C)
- Solid
Electronic Structure
- Electron configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14
- Short configuration
- [Rn] 5f14 7s2
- Electrons per shell
- 2, 8, 18, 32, 32, 8, 2
- Electronegativity (Pauling)
- 1.30
- Electron affinity
- -223 kJ/mol
- 1st ionization energy
- 642 kJ/mol
Physical properties
- Melting point
- 826.9 °C (1100 K)
- Boiling point
- —
- Density
- —
- Molar heat capacity
- —
Chemical behavior of nobelium
Nobelium has fourteen outer electrons ([Rn] 5f¹⁴ 7s²) and acts as +2, with +3 accessible but secondary: its full 5f shell stabilizes the loss of only two electrons, something unique among actinides that makes it behave like an alkaline earth metal. Its electronegativity is low (1.30). Nobody has seen it with the naked eye: only a few atoms have been created at a time, which disappear in minutes.
Reactivity
4 No + 3 O₂ → 2 No₂O₃
In air it would be expected to oxidize to sesquioxide like the other actinides; in practice only traces have been observed in matrices.
No + 2 HCl → NoCl₂ + H₂
In acidic solution it preferably forms nobelium(II) salts, reducing water more easily than its +3 neighbors: the element's alkaline earth behavior.
²⁵⁷No + n → ²⁵⁸No → (spontaneous fission)
Heavy nobelium isotopes are prey to spontaneous fission: the nuclear barrier limiting its study.
²⁵⁹No → ²⁵⁵Fm + α
No-259, the most stable (58 minutes), decays emitting alpha particles to fermium: the reaction that confirmed its discovery.
Notable compounds
| Compound | Formula | Use or importance |
|---|---|---|
| Nobelium chloride | NoCl₂ | Characteristic +2 state |
| Nobelium(III) chloride | NoCl₃ | Accessible +3 state |
| No²⁺ solution | No(aq)²⁺ | Ionic chromatography studies |
| Nobelium oxide | NoO | +2 chemistry prediction |
| No-257 target | ²⁵⁷No | Nuclear deformation measurement |
Electron shell distribution
View in the atom builderIsotopes
No nobelium isotope is stable. Nobelium-259 (²⁵⁹No, 58 minutes) is the most stable; nobelium-257 (²⁵⁷No, 25 s) is the most used for nuclear property studies, such as the elongated nucleus deformation, in the shape of a rugby ball. Its heavy isotopes end up undergoing spontaneous fission.
Occurrence and production
It does not exist in nature: all nobelium is born in accelerators, bombarding californium with carbon in Dubna or curium with neon at Berkeley. It is obtained in quantities of thousands of atoms lasting minutes: never in macroquantities.
History and origin of the name
The discovery was subject to controversy between Dubna (Flyorov, 1956, Nobel attribution unconfirmed) and Berkeley (Ghiorso and Seaborg, 1958, confirmation with a single decay chain). The name honors Alfred Nobel, founder of the prizes that reward these very discoveries.
Applications and relevance of nobelium
Uses of the element
Nobelium has no practical applications: its short half-life and scarcity prevent any medical, industrial or technological use. It serves to study the limits of nuclear stability and the chemistry at the end of the actinides.
Uses of its compounds
Its compounds in solution allowed measuring redox potentials with single-atom techniques and testing the stability of the full 5f shell. Its elongated nucleus feeds nuclear structure models.
Health, safety and environment
Biological role
It has no known biological function and is extremely radiotoxic. Work is done with quantities of thousands of atoms diluted in matrices.
Safety
It is handled only in Dubna, Oak Ridge and GSI, in shielded cells. Its alpha decays and the spontaneous fission of its neighboring isotopes require strict containment.
Environment
There are no spills: traces are fixed in solid matrices treated as radioactive waste and vitrified.
Frequently asked questions about Nobelium
What would nobelium be like if you could see it?
If it existed in sufficient quantity, nobelium would probably be a silvery, shiny and soft metal, similar to other actinides such as curium or californium. However, nobody has ever seen it with the naked eye: only a few atoms have been created at a time, and they disappear in minutes. Its real appearance remains a prediction based on neighboring elements of the periodic table.
What would happen if you had a nobelium piece the size of a coin?
It would be impossible to keep it: its radioactivity would be so intense that the metal would heat up, be damaged from within and disintegrate rapidly. Moreover, it would disappear within hours or days, transforming into other elements. A nobelium coin does not exist nor will it ever exist, because only a few atoms have been created at a time.
Does nobelium resemble ytterbium?
Yes, and this comparison is very useful for scientists. Ytterbium is a much more common and stable lanthanide that also prefers the +2 oxidation state. By studying how ytterbium behaves in solution, researchers can predict how nobelium will act, which is almost impossible to handle. It is like using a more accessible chemical cousin to understand an almost unreachable element.
Could nobelium have any use in the future?
For now, no. Its too-short half-life and extreme scarcity prevent any practical application, whether medical, industrial or technological. If a much more stable isotope were discovered one day, it could be considered for advanced research, but today nobelium only serves to expand knowledge about how the heaviest elements of the periodic table behave.
Why does nobelium resemble calcium more than other actinides?
In solution, nobelium tends to lose only two electrons and form a +2 charged ion, like calcium or strontium. Most actinides lose three electrons and form +3 ions. This difference makes nobelium chemically behave more like an alkaline earth metal than a typical actinide, something unique within its family.
Why does nobelium last so little time?
The most stable isotope, nobelium-259, has a half-life of only 58 minutes. This means that in less than an hour, half of a sample's atoms will have transformed into other elements. This instability is due to its nucleus, with 102 protons, being too large and repulsive to remain bound for a long time.
What experiments have been done with nobelium?
Scientists have managed to study nobelium in solution, verifying that it behaves as a +2 ion and that it can be separated from other actinides through chromatography techniques. Its nuclear properties have also been measured, such as the shape of its nucleus, which turns out to be elongated, like a rugby ball, instead of spherical. These experiments are done with minimal quantities, sometimes of only a few thousand atoms.
Main sources consulted: PubChem, Royal Society of Chemistry, NIST, IUPAC. Last revision: November 2026.