No · Element 102 · Actinide
The subject of a decade-long discovery dispute between Swedish, American and Soviet teams.
Structure
Not a diagram of dots on rings — a Monte-Carlo sample of the actual probability density |ψ|² for each occupied subshell. Drag to rotate. Blue and violet mark opposite signs of the wavefunction, which is what makes bonding possible.
Measured values
Every bar shows where nobelium sits among all 118 elements for that property.
Sources: IUPAC 2021 standard atomic weights · CRC Handbook of Chemistry and Physics · NIST. Values marked ~ are predicted rather than measured.
Same element, different neutrons
All nobelium atoms have the same number of protons, 102, and differ only in their number of neutrons: those variants are its isotopes. None of them is stable. The longest-lived known isotope, No-259, has 157 neutrons and a half-life of 58 min.
| ISOTOPE | Neutrons | Natural Abundance | Half-life | Decay Mode |
|---|---|---|---|---|
| No-253 | 151 | — | 1.62 min | α (55%), ε/β⁺ (45%) |
| No-254 | 152 | — | 51.2 sec | α (90%), ε (10%) |
| No-255 | 153 | — | 3.52 min | ε/β⁺ (70%), α (30%) |
| No-257 | 155 | — | 24.5 sec | α, ε, SF |
| No-259 longest-lived | 157 | — | 58 min | α, ε/β⁺, SF |
Here the classroom shortcut, rounded atomic mass (259) minus atomic number, gives the same answer: 157.
Decay modes
Data: IAEA Nuclear Data Section, LiveChart of Nuclides, ground-state evaluations, retrieved October 10, 2026. Abundance is the share of atoms in the natural element; a dash means the isotope has no standard natural abundance.
Size, to scale
Radius 246 pm — that is 0.246 nm, so about 2.03 million of them side by side would span a millimetre.
Thermal range
Nobelium melts at 1100 K; its boiling point has not been measured.
The story
The subject of a decade-long discovery dispute between Swedish, American and Soviet teams.
Nobelium's discovery became one of the most contentious disputes in Cold War science. The first claim came from the Nobel Institute in Stockholm, Sweden in 1957, followed by competing claims from Soviet scientists at Dubna and American researchers at Berkeley, creating a decade-long priority battle.
In 1957, Swedish physicists at the Nobel Institute announced element 102's discovery, bombarding curium-244 with carbon-13 ions. They proposed the name "nobelium" in honor of Alfred Nobel. However, other laboratories couldn't reproduce their results, and the Swedish team eventually retracted their claims.
The definitive synthesis was achieved in 1966 by Georgy Flerov's team at the Joint Institute for Nuclear Research in Dubna, Soviet Union. They successfully created nobelium-256 by bombarding uranium-238 with neon-22 ions, providing conclusive evidence of element 102's existence.
The International Union of Pure and Applied Chemistry finally resolved the controversy in 1992, crediting the Soviet team with the official discovery. However, the name "nobelium" was retained due to its widespread use in scientific literature, creating an unusual situation where the namers weren't the discoverers.
The nobelium controversy reflected broader Cold War tensions in science, with national pride and political prestige tied to element discoveries. The eventual resolution demonstrated international scientific cooperation's ability to overcome political divisions in pursuit of truth.
Applications
Nobelium plays a critical role in understanding superheavy element chemistry, particularly investigating how electron orbitals behave under very high nuclear charge conditions. Scientists study nobelium to validate relativistic effects predictions in heavy atoms and explore chemical bonding beyond traditional periodic trends.
Research teams use nobelium to investigate the end of the actinide series and transition to superheavy elements. This research helps define where f-orbital filling ends and provides insights into electron configuration patterns that influence chemical properties of elements 103 and beyond.
Nobelium isotopes serve as excellent subjects for studying spontaneous fission and alpha decay chains, providing data crucial for understanding nuclear stability limits and predicting properties of undiscovered superheavy elements in the theoretical "island of stability."
Physicists employ nobelium in experiments that test quantum mechanical calculations for superheavy atoms, validating theoretical predictions about nuclear shell effects, binding energies, and optimal synthesis pathways for creating even heavier elements.
Nobelium research drives development of ultra-sensitive analytical techniques including single-atom chemistry methods, advanced mass spectrometry, and sophisticated radiation detection systems that push the boundaries of what's possible in nuclear science.
Nobelium applications are exclusively limited to advanced nuclear research laboratories including GSI in Germany, RIKEN in Japan, and Berkeley Lab in the United States. These facilities use nobelium for fundamental nuclear physics research and superheavy element synthesis studies.
Research teams utilize nobelium in gamma-ray spectroscopy and nuclear decay studies to measure precise nuclear properties including spin, parity, and magnetic moments. These measurements provide essential data for understanding nuclear shell structure in superheavy elements.
Scientists perform pioneering single-atom chemical experiments with nobelium, studying oxidation states and chemical behavior using just a few atoms. These experiments represent the frontier of chemistry, working at the limit of material science.
Nobelium research necessitates development of advanced detection systems including position-sensitive detectors, time-of-flight systems, and advanced particle identification methods that advance nuclear instrumentation technology for future discoveries.
Where it comes from
0 mg/kg of Earth's crust · more abundant than 0% of elements
Nobelium is known only from artificial synthesis in particle accelerators and has never been found naturally on Earth or detected in stellar spectra. This superheavy element is one of humanity's most exclusive creations and has never been found in nature.
Scientists create nobelium by bombarding curium or californium targets with carbon, oxygen, or neon ions in linear accelerators. The original disputed synthesis involved bombarding curium-244 with carbon-13 nuclei, though definitive production wasn't achieved until the 1960s.
The most stable nobelium isotope, 259No, has a half-life of only 58 minutes, making it impossible for any primordial nobelium to have survived since Earth's formation. Current synthetic nobelium atoms exist for mere minutes before decaying into lighter elements.
Global nobelium production is measured in individual atoms per experiment, with worldwide synthesis totaling perhaps a few thousand atoms annually. The element requires sophisticated particle accelerators, rare target materials, and enormous energy inputs for synthesis.
Unlike elements formed in stellar nucleosynthesis or cosmic ray interactions, no nobelium survives in nature because of its short half-lives, and whether the r-process in neutron star mergers briefly makes it is an open question. Every known nobelium atom was made in a laboratory.
Handling
Nobelium is radioactive. It has no stable isotope — every nucleus decays. Handling requires appropriate shielding and licensing.
Nobelium is radioactive, but it is made only a few atoms at a time in heavy-ion accelerators. Its isotopes decay by alpha emission, electron capture and spontaneous fission; the longest-lived, nobelium-259, has a half-life of about an hour. No weighable amount of nobelium has ever existed, so the atoms themselves cannot deliver a meaningful radiation dose to anyone.
The hazards in this research come from the experiment, not the element: the accelerator beam, radioactive targets and activated equipment, and the waste these produce. Materials that become contaminated are disposed of as radioactive waste under national rules.
Staff follow the standard occupational radiation rules: annual dose limits, personal dose monitoring and keeping doses as low as reasonably achievable. Workers under 18 face much lower dose limits than adults: one tenth of the adult limits under US Nuclear Regulatory Commission rules (10 CFR 20.1207), and 1 mSv a year at US Department of Energy laboratories (10 CFR 835.207). A worker who declares a pregnancy is limited to 5 mSv to the fetus over the whole pregnancy (10 CFR 20.1208 and 835.206).
Quick answers
Nobelium (symbol No) is element 102 on the periodic table, an actinide in period 7. The subject of a decade-long discovery dispute between Swedish, American and Soviet teams. At room temperature it is expected to be a solid, and it is radioactive.
[Rn] 5f¹⁴ 7s², giving 7 occupied shells with the distribution 2, 8, 18, 32, 32, 8, 2.No sample of nobelium has ever been condensed, so its melting point is calculated rather than measured: it is predicted to melt at 1100 K (826.9 °C). Its boiling point has not been measured.
Nobelium has no stable isotope, so it has no standard atomic weight. The figure quoted, 259, is the mass number of its longest-lived known isotope.
Nobelium has no stable isotope. Its longest-lived known isotope, No-259, has 157 neutrons (mass number 259 minus atomic number 102) and a half-life of 58 min. The classroom shortcut, rounded atomic mass (259) minus atomic number, gives the same 157.
Nobelium is predicted to have a density of about 9.9 g/cm³, though no sample large enough to weigh has ever been made. Water is 1.0 g/cm³ for comparison.
Nobelium has a Pauling electronegativity of 1.3. The scale runs from 0.70 (francium, the least greedy for electrons) to 3.98 (fluorine, the most). Values in this middle band tend to form covalent rather than strongly ionic bonds.
Nobelium was discovered in 1958 by Joint Institute for Nuclear Research. Origin of the name: Alfred Nobel.
Nobelium does not occur naturally on Earth in any meaningful quantity — it is made in a reactor or an accelerator.
Yes. Nobelium has no stable isotope — every one of its nuclei decays. It does not occur in usable quantities in nature and must be synthesised.