Rutherfordium · element 104
The first element past the actinides, born in a Cold War naming dispute and chemically a heavier hafnium
Key facts
Rutherfordium is the first transactinide. Once the 5f shell has filled, electrons return to the 6d orbitals and the periodic table resumes its normal march across the transition metals. Rutherfordium sits under hafnium in group 4, and the handful of chemistry experiments performed on it confirm that it does indeed behave like a heavier hafnium, forming a volatile tetrachloride and a stable +4 ion.
Its name honours Ernest Rutherford, the New Zealand-born physicist who discovered the atomic nucleus. But for nearly three decades the element had two names, kurchatovium in the Soviet Union and rutherfordium in the West, in a dispute that came to be called the Transfermium Wars.
Where it is found
Rutherfordium does not occur in nature. Its most stable isotope, rutherfordium-267, appears to survive for a matter of hours, and the isotopes used in experiments last seconds to a little over a minute. It is one of the elements that exist on Earth only during the moments after an accelerator experiment produces them.
It is synthesised by fusing a light ion beam into a heavy actinide target. Bombarding curium-248 with oxygen-18 produces rutherfordium-261, which lives long enough, around a minute, for chemists to study it. Californium-249 with carbon-12 or carbon-13 was the route used at Berkeley in 1969. Production is a few atoms per hour at best.
How it was discovered
In 1964 a team led by Georgy Flerov at the Joint Institute for Nuclear Research in Dubna bombarded plutonium-242 with neon-22 and reported a spontaneous fission activity that they assigned to element 104. They named it kurchatovium after Igor Kurchatov, head of the Soviet nuclear programme. The result was hard to interpret because spontaneous fission alone does not identify which element decayed.
In 1969 Albert Ghiorso's group at Berkeley produced rutherfordium-257 and rutherfordium-259 from californium-249 and carbon ions, and identified the atoms through their alpha decay chains to known nobelium isotopes, a more definitive signature. They proposed rutherfordium. Both names appeared in textbooks for decades. In 1992 a joint IUPAC and IUPAP group assigned shared credit, and in 1997 IUPAC adopted rutherfordium for element 104, while kurchatovium was dropped.
What we use it for
Rutherfordium has no uses beyond research. Its role in science is to test whether the periodic table still works at the top of the transition metals. Chemists have a one-minute isotope to work with, so experiments are automated: atoms are swept from the target in a gas stream, converted into chlorides or bromides, and their behaviour compared with that of hafnium and zirconium under identical conditions.
These experiments show that rutherfordium forms a volatile tetrachloride much like hafnium tetrachloride, and that in acid solution it forms +4 ions and complexes similar to hafnium's. Subtle differences reveal the influence of relativistic effects on the 6d and 7s electrons. Such work helps decide whether even heavier elements will follow their groups or begin to behave in unexpected ways.
Reading the numbers
None of rutherfordium's bulk properties have been measured. The melting point of about 2,130 °C, boiling point of about 5,530 °C and density of 23.2 grams per cubic centimetre in our data are all theoretical estimates, based on its position below hafnium and on relativistic calculations. If the density is right, rutherfordium would be denser than any element that has actually been weighed, roughly three times iron. The configuration [Rn] 5f14 6d2 7s2 is the group 4 pattern: two d electrons and two s electrons available for bonding, giving the +4 oxidation state seen in titanium, zirconium and hafnium. No electronegativity is listed because it has never been measured. Its first ionisation energy of about 580 kilojoules per mole is a calculated value.
Safety and the environment
Rutherfordium exists only as a few atoms at a time and decays within minutes or hours, so it has no environmental presence and cannot affect the public. The safety concerns in rutherfordium experiments are those of the actinide targets, which are strongly radioactive, and the accelerator beam. All are managed with shielding, remote handling and monitoring.
Did you know?
- Rutherfordium was called kurchatovium in Soviet and some other publications for almost thirty years before IUPAC settled on rutherfordium in 1997.
- If its predicted density of about 23 grams per cubic centimetre is correct, a golf-ball-sized piece would weigh close to a kilogram.
- Chemistry experiments on rutherfordium are done with isotopes that live about a minute, using gas streams to move atoms from the target to detectors.
- Ernest Rutherford won the Nobel Prize in Chemistry in 1908, and joked that his sudden change from physicist to chemist was the fastest transformation he had ever observed.
- Rutherfordium is the first element in which the 6d orbitals hold the outer electrons, returning the table to transition-metal behaviour after the actinides.
More in the superheavy elements
The nearest neighbours of rutherfordium in the family, by atomic number.
See all 15 superheavy elements on one page, or browse all 118 elements. Also listed under the transition metals.
Frequently asked questions
What is rutherfordium used for?
Nothing practical. It is produced a few atoms at a time to study whether the heaviest elements still follow the trends of their groups in the periodic table.
Who discovered rutherfordium?
Credit is shared between the Dubna team in 1964 and the Berkeley team in 1969, following a review in 1992. IUPAC adopted the name rutherfordium in 1997.
Is rutherfordium a transition metal?
Yes. It is the first transactinide, sitting in group 4 below hafnium, and its chemistry matches hafnium's closely, forming +4 ions and a volatile tetrachloride.
How long does rutherfordium last?
Its most stable isotope survives for hours, while the isotopes used in chemistry experiments last around a minute.
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Written by Anthony. Updated September 2026. Numerical data from Periodic-Table-JSON (CC BY-SA), cross-checked against the Rutherfordium reference article. Spotted an error? Tell us.