Rutherfordium

Physical properties

The chemical and physical properties of Unq (or rutherfordium) are homologous with theelement hafnium (72Hf ), located just above it in group 4 (IVB) in the periodic table. It wasfirst claimed to be produced artificially by the Joint Institute for Nuclear Research (JINR)located in Dubna, Russia. The Russian scientists used a cyclotron that smashed a target ofplutonium-242 with very heavy ions of neon-22, resulting in the following reaction: ₉₄Pu-242 + ₁₀Ne-22 →₁₀₄Unq-260 + 4₀n-1 (alpha radiation). The Russians named Unq-260 “kurchatovium”(Ku-260) for the head of their center, Ivan Kurchatov. (See details in the next section,“History.”).

Isotopes

There are a total of 15 isotopes for rutherfordium, ranging from Rf-253 to Rf-264. Their half-lives range from 23 microseconds to 10 minutes. They are all artificiallymade, radioactive, and unstable. Their decay modes are a combination of alpha decayand spontaneous fission (SF).

Origin of Name

Named by the transition naming system of the IUPAC (unnilquadium) and later named after the New Zealand scientist Ernest Rutherford (rutherfordium).

History

Canadian, and British physicist); Rf; at. wt. [261]; at. no. 104. In 1964, workers of the Joint Nuclear Research Institute at Dubna (Russia) bombarded plutonium with accelerated 113 to 115 MeV neon ions. By measuring fission tracks in a special glass with a microscope, they detected an isotope that decays by spontaneous fission. They suggested that this isotope, which has a half-life of 0.3 ± 0.1 s, might be 104.
Element 104, the first transactinide element, is expected to have chemical properties similar to those of hafnium. It would, for example, form a relatively volatile compound with chlorine (a tetrachloride). The Soviet scientists have performed experiments aimed at chemical identification, and have attempted to show that the 0.3-s activity is more volatile than that of the relatively nonvolatile actinide trichlorides. This experiment does not fulfill the test of chemically separating the new element from all others, but it provides important evidence for evaluation. New data, reportedly issued by Soviet scientists, have reduced the half-life of the isotope they worked with from 0.3 to 0.15 s. The Dubna scientists suggest the name kurchatovium and symbol Ku for Element 104, in honor of Igor Vasilevich Kurchatov (1903–1960), late Head of Soviet Nuclear Research. The Dubna Group also has proposed the name dubnium for Element 104. In 1969, Ghiorso, Nurmia, Harris, K. A. Y. Eskola, and P. I. Eskola of the University of California at Berkeley reported they had positively identified two, and possibly three, isotopes of Element 104. The group also indicated that after repeated attempts so far they have been unable to produce isotope 260104 reported by the Dubna groups in 1964. The discoveries at Berkeley were made by bombarding a target of ²⁴⁹Cf with 12C nuclei of 71 MeV, and 13C nuclei of 69 MeV. The combination of 12C with 249Cf followed by instant emission of four neutrons produced Element 257104. This isotope has a half-life of 4 to 5 s, decaying by emitting an alpha particle into ²⁵³No, with a half-life of 105 s. The same reaction, except with the emission of three neutrons, was thought to have produced ²⁵⁸104 with a half-life of about 1/100 s. Element 259104 is formed by the merging of a 13C nuclei with 249Cf, followed by emission of three neutrons. This isotope has a half-life of 3 to 4 s, and decays by emitting an alpha particle into ²⁵⁵No, which has a half-life of 185 s. Thousands of atoms of ²⁵⁷104 and ²⁵⁹104 have been detected. The Berkeley group believes its identification of ²⁵⁸104 was correct. Eleven isotopes of Element 104 have now been identified. The Berkeley group proposed the name rutherfordium (symbol Rf) for the new element, in honor of Ernest Rutherford. This name was formally adapted by IUPAC in August 1997.

Uses

There are no uses for unnilquadium (rutherfordium), except for high-energy nuclear-particleresearch.

Definition

rutherfordium: Symbol Rf. A radioactivetransactinide element; a.n.104. It was first reported in 1964 atDubna, near Moscow, and in 1969 it was detected by A. Ghiorso and ateam at Berkeley, California. It canbe made by bombarding californium-249 nuclei with carbon-12 nuclei.

Definition

A radioactive metal not found naturally on earth. It is the first transactinide metal. Atoms of rutherfordium are produced by bombarding ²⁴⁹Cf with 12C or by bombarding ²⁴⁸Cm with 18O. Symbol: Rf; m.p. 2100°C (est.); b.p. 5200°C (est.); r.d. 23 (est.); most stable isotope ²⁶¹Rf (half-life 65s).

Hazard

The hazards of unnilquadium are the same as for any radioactive element. Since there areonly a few atoms with short half-lives produced at a time in scientific laboratories, there islittle danger to the public.