Rf · Element 104 · Transition metal
The first transactinide — and chemically a heavier cousin of hafnium, not an actinide at all.
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 rutherfordium 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 rutherfordium atoms have the same number of protons, 104, and differ only in their number of neutrons: those variants are its isotopes. None of them is stable. The longest-lived known isotope, Rf-267, has 163 neutrons and a half-life of ~1.3 hr.
| ISOTOPE | Neutrons | Natural Abundance | Half-life | Decay Mode |
|---|---|---|---|---|
| Rf-257 | 153 | — | 4.4 sec | α (79.3%), ε (19.4%), SF (1.3%) |
| Rf-261 | 157 | — | 68 sec | α |
| Rf-263 | 159 | — | 10 min | α |
| Rf-265 | 161 | — | ~1.0 min | SF |
| Rf-267 longest-lived | 163 | — | ~1.3 hr | SF, α |
Here the classroom shortcut, rounded atomic mass (267) minus atomic number, gives the same answer: 163.
Decay modes
~ marks a half-life whose published uncertainty is larger than the value itself.
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 247 pm — that is 0.247 nm, so about 2.02 million of them side by side would span a millimetre.
Thermal range
Rutherfordium is liquid over a 3400 K window, from 2400 K to 5800 K.
The story
The first transactinide — and chemically a heavier cousin of hafnium, not an actinide at all.
Rutherfordium's discovery became a major Cold War scientific competition between Soviet scientists at Dubna and American researchers at Berkeley. Both teams claimed priority, leading to a naming controversy that lasted decades until IUPAC resolution in 1997.
In 1964, Georgy Flerov's team at the Joint Institute for Nuclear Research in Dubna reported creating element 104 by bombarding plutonium-242 with neon-22 ions. They proposed the name "kurchatovium" after Igor Kurchatov, father of the Soviet atomic bomb program.
In 1969, Albert Ghiorso's team at Berkeley Lab reported independent synthesis of element 104 by bombarding californium-249 with carbon-12 and carbon-13 ions. They proposed "rutherfordium" honoring New Zealand physicist Ernest Rutherford, father of nuclear physics.
The International Union of Pure and Applied Chemistry resolved the controversy in 1997, officially recognizing both teams' contributions but adopting "rutherfordium" as the standard name. This decision balanced scientific achievement with international diplomacy.
Recent advances in detection technology have confirmed rutherfordium's properties and enabled discovery of new isotopes, including the 2025 discovery of rutherfordium-252 with high precision, validating theoretical predictions about superheavy nuclear behavior.
Applications
Rutherfordium serves as the first true superheavy element beyond the actinide series, providing crucial insights into how matter behaves under very high nuclear charge conditions. Scientists use rutherfordium to validate theoretical predictions about electron configurations and chemical properties in the superheavy region.
Research teams employ rutherfordium to investigate nuclear shell effects and fission barriers that govern superheavy element stability. Rutherfordium-252, first reported in 2025 with a ground state that fissions in about 60 nanoseconds, provides critical data for understanding the "island of stability" predictions.
Rutherfordium enables pioneering studies of relativistic effects in chemistry, where electron velocities reach significant fractions of light speed due to very high nuclear charge. These studies validate quantum mechanical calculations for superheavy atoms and predict chemical behavior of undiscovered elements.
Scientists use rutherfordium research to develop and refine hot fusion reaction methods for creating superheavy elements. These techniques involve bombarding actinide targets with medium-mass ions, establishing pathways for synthesizing even heavier elements.
Rutherfordium studies contribute to understanding r-process nucleosynthesis in neutron star mergers and supernovae, which are thought to make nuclei of mass 260 or more that split almost at once; no rutherfordium has ever been found in nature. This research helps explain heavy element abundance patterns in the universe.
Rutherfordium applications are exclusively limited to world-leading nuclear research facilities including GSI in Germany, RIKEN in Japan, Berkeley Lab in the USA, and JINR in Russia. These facilities use rutherfordium for advanced superheavy element physics and chemistry research.
Research teams utilize rutherfordium in precision nuclear measurements including spontaneous fission studies, alpha-decay energy determination, and nuclear lifetime measurements. The recent discovery of rutherfordium-252 provides new data on nuclear stability limits.
Scientists perform important atom-by-atom chemical studies with rutherfordium, investigating oxidation states, complex formation, and chemical bonding using gas-phase chromatography and extraction techniques at the limits of analytical chemistry.
Rutherfordium research drives development of advanced detection technologies including gas-filled separators, position-sensitive detectors, and sophisticated data acquisition systems that enable identification and study of individual superheavy atoms.
Where it comes from
0 mg/kg of Earth's crust · more abundant than 0% of elements
Rutherfordium is known only from artificial synthesis in particle accelerators and has never been detected naturally on Earth or in cosmic phenomena. This superheavy element has never been found anywhere in nature.
Scientists make rutherfordium directly by bombarding californium-249 with carbon-12 or -13 ions or curium-248 with oxygen ions; its longest-lived isotope, rutherfordium-267, appears at the end of decay chains of flerovium made by bombarding plutonium-242 with calcium-48 ions in a cyclotron. These "hot fusion" reactions require precise energy calibration to overcome strong electrostatic repulsion.
The most stable rutherfordium isotope, 267Rf, has a half-life of only 1.3 hours, while most isotopes decay within seconds or minutes. The recently discovered 252Rf fissions in about 60 nanoseconds from its ground state, and an excited isomeric state survives about 13 microseconds, demonstrating the instability of superheavy nuclei.
Global rutherfordium production is measured in individual atoms per experiment, with successful synthesis runs producing perhaps 1-10 atoms per hour. Worldwide annual production totals fewer than thousands of atoms across all research facilities combined.
Unlike elements formed through stellar nucleosynthesis or cosmic ray interactions, no rutherfordium survives in nature, and whether the r-process briefly makes it in neutron star mergers is still an open question. It represents a high point of artificial element creation.
Handling
Rutherfordium is radioactive. It has no stable isotope — every nucleus decays. Handling requires appropriate shielding and licensing.
Rutherfordium is radioactive, but it is made only a few atoms at a time in heavy-ion accelerators. Its isotopes decay by spontaneous fission, alpha emission and electron capture; the longest-lived, rutherfordium-267, has a half-life of about 1.3 hours. No weighable amount of rutherfordium 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. They are controlled by shielding and remote handling, and the waste is managed as radioactive waste under national radiation protection 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
Rutherfordium (symbol Rf) is element 104 on the periodic table, a transition metal in period 7, group 4. The first transactinide — and chemically a heavier cousin of hafnium, not an actinide at all. At room temperature it is expected to be a solid, and it is radioactive.
[Rn] 5f¹⁴ 6d² 7s², giving 7 occupied shells with the distribution 2, 8, 18, 32, 32, 10, 2.No sample of rutherfordium has ever been condensed, so both figures are calculated rather than measured: it is predicted to melt at 2400 K (2126.9 °C) and boil at 5800 K (5526.9 °C). That puts it among the most refractory elements — it stays solid at temperatures that vaporise most metals.
Rutherfordium has no stable isotope, so it has no standard atomic weight. The figure quoted, 267, is the mass number of its longest-lived known isotope.
Rutherfordium has no stable isotope. Its longest-lived known isotope, Rf-267, has 163 neutrons (mass number 267 minus atomic number 104) and a half-life of ~1.3 hr. The classroom shortcut, rounded atomic mass (267) minus atomic number, gives the same 163.
Rutherfordium is predicted to have a density of about 23.2 g/cm³, though no sample large enough to weigh has ever been made. Water is 1.0 g/cm³ for comparison.
Rutherfordium was discovered in 1964 by JINR Dubna & Berkeley. Origin of the name: Ernest Rutherford.
Rutherfordium does not occur naturally on Earth in any meaningful quantity — it is made in a reactor or an accelerator.
Yes. Rutherfordium has no stable isotope — every one of its nuclei decays. It does not occur in usable quantities in nature and must be synthesised.