Rutherfordium

melting point: Unknown
boiling point:Unknown
density:Unknown
most common ions:Unknown

Rutherfordium is the first transactinide element. It was discovered in 1969 by Albert Ghiorso and his coworkers, who carried out the reactions ²⁴⁹Cf (¹²C, 4n)→ ²⁵⁷Rf (half-life of approximately 3.8 seconds) and ²⁴⁹Cf(¹³C, 3n) [→] ²⁵⁹Rf (half-life of approximately 3.4 seconds). There are ten known isotopes of rutherfordium, having mass numbers that range from 253 to 262, the isotope with the longest measured half-life being ²⁶¹Rf (half-life of approximately 1.1 minutes). After its discovery, it was postulated that rutherfordium, as the first transactinide element, should be a member of a new, fourth transition series, extending from Z = 104 to Z = 112, and an atom in which the 6d electronic shell is filled. The outer orbital electronic configuration of Rf should be [Rn]5f ¹⁴6d ²7s ². As such, it should behave similarly to its analogs titanium and hafnium and should form volatile tetrachlorides that are less volatile than HfCl₄. The first gas chromatographic studies showed that rutherfordium forms more volatile chlorides than hafnium—a deviation from Periodic Table trends that was predicted from relativistic calculations . The first aqueous chemistry studies showed the neutral and anionic complexes of Rf to behave like the corresponding complexes of the Group IVB elements, rather than of the trivalent actinides, demonstrating that Rf is indeed a transactinide. Detailed studies of the extraction chromatography of Rf complexes have shown chemical behavior similar to that observed of Rf complexes in gas chromatographic experiments—that is, Rf does not behave as expected according to a simple extrapolation of Periodic Table trends, but in a more complicated manner. For example, in the extraction of substances with tributylphosphate, the extraction sequence Zr > Rf > Hf is observed. These and other experiments show that the aqueous chemistry of rutherfordium is a challenge to current relativistic molecular theories.

see also Actinium; Berkelium; Einsteinium; Fermium; Lawrencium; Mendelevium; Neptunium; Nobelium; Plutonium; Protactinium; Thorium; Uranium.

Walter Loveland

Bibliography

Seaborg, Glenn T., and Loveland, Walter D. (1990). The Elements beyond Uranium. New York: Wiley.

rutherfordium , artificially produced radioactive chemical element; symbol Rf; at. no. 104; mass number of most stable isotope 261; m.p., b.p., and sp. gr. unknown; valence +4. It is the first transuranium element beyond the actinide series , thus being the first of the transactinide elements . Situated in Group 4 of the periodic table , it has properties similar to those of hafnium and zirconium .

In 1964 a Soviet team led by G. N. Flerov at the Joint Institute for Nuclear Research at Dubna announced the discovery of element 104. They claimed to have isolated an isotope with mass number 260 and a half-life of 0.3 sec by bombarding plutonium-242 atoms with neon-22 ions. Subsequently, they suggested that element 104 be named kurchatovium (symbol Ku) to honor Igor Kurchatov, a Soviet pioneer in nuclear physics. In 1969, an American research team led by A. Ghiorso at the Lawrence Berkeley National Laboratory announced that, while they had been unable to confirm the Dubna group's results, they had identified at least two isotopes of element 104 different from the one identified by the Soviet scientists. They bombarded californium-249 atoms with carbon-12 and carbon-13 ions to creates isotopes with mass numbers 257 (half-life of 4.8 sec), 259 (half-life of 3 sec), and possibly 258 (half-life of 13 msec). Disputing the Soviet claim of discovery, the Americans suggested the name rutherfordium to honor the British physicist Lord Ernest Rutherford . An international committee set up to resolve such disputes decided in 1992 that the Berkeley and Dubna laboratories should share credit for the discovery. The syntheses of at least 10 isotopes of rutherfordium, with half-lives ranging from 0.5 msec (Rf-254) to 65 sec (Rf-261), have been confirmed.

In 1994 a committee of the International Union of Pure and Applied Chemistry (IUPAC), convened to resolve naming disputes for the transactinide elements, recommended that element 104 be named dubnium in recognition of the work done at the Dubna laboratory. The committee also recommended that element 106, which had been called seaborgium by the American team that discovered it, be called rutherfordium. In 1997, however, the name rutherfordium for element 104 was recognized internationally.

See also synthetic elements .

rutherfordium (symbol Rf) Synthetic, radioactive, metallic element, first of the transactinide elements. The longest-lived of its ten isotopes has a half-life of 70 seconds (the longest yet identified). It is named after the New Zealand-born British physicist Ernest Rutherford. Properies: at.no. 104. It was first given the temporary name of unnilquadium until 1997.

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