unnilquadium

Temporary name of the chemical element with atomic number 104. Its discovery (and hence the name) is controversial.

In 1964 G. N. Flerov and others at the Joint Institute for Nuclear Research in Dubna, U.S.S.R claimed to have identified it, and suggested the name kurchatovium (symbol, Ku). Subsequent experiments at the University of California, Berkeley by A. Ghiorso and others suggested that the evidence of the element’s identity put forward by the Russian workers was not valid, and, having obtained their own evidence for the synthesis of the element, in 1969 they proposed the name rutherfordium (symbol Rf). The latter name was used for some time in the United States, but in August 1994 a committee of the International Union of Pure and Applied Physics named element 104 dubnium, in honor of the Joint Institute for Nuclear Research in Dubna.

In August 1997, the IUPAC Commission on Nomenclature in Inorganic Chemistry recommended the element be called rutherfordium (symbol, Rf),¹ and element 105 was named dubnium.

1. Inorganic Chemistry Division; Commission on Nomenclature of Inorganic Chemistry.
Names and Symbols of Transfermium Elements (IUPAC recommendation 1997)
Pure and Applied Chemistry, vol. 69, no. 12, pages 2471–2473 (1997).

Available on the Web as a pdf file accessible through www.iupac.org/projects/1995/220_30_95.html