Dubnium is a synthetic chemical element with the symbol Db and atomic number 105. It is highly radioactive: the most stable known isotope, dubnium-268, has a half-life of about 28 hours. This greatly limits the extent of research on dubnium. It does not occur naturally on Earth and is produced artificially. The Soviet Joint Institute for Nuclear Research (JINR) claimed the first discovery of the element in 1968, followed by the American Lawrence Berkeley Laboratory in 1970.
Both teams proposed their names for the new element and used them without formal approval. The long-standing dispute was resolved in 1993 by an official investigation of the discovery claims by the Transfermium Working Group, formed by the International Union of Pure and Applied Chemistry and the International Union of Pure and Applied Physics, resulting in credit for the discovery being officially shared between both teams. The element was formally named Dubnium in 1997 after the town of Dubna, the site of the JINR.
It should share most properties, such as its valence electron configuration and having a dominant +5 oxidation state, with the other group 5 elements, with a few anomalies due to relativistic effects. A limited investigation of dubnium chemistry has confirmed this. Solution chemistry experiments have revealed that dubnium often behaves more like niobium rather than tantalum, breaking periodic trends.
Characteristics of Dubnium
- The metal behaves as a solid at temperatures of 20o °C. It occurs as a synthetic element in nature, and it is artificially produced by the bombardment of the californium-249 with the nuclei nitrogen-1.
- Dubnium is a highly radioactive element with only one single stable isotope dubnium-268 which has a half-life measuring about only 32 hours and gets decayed through the process of spontaneous fission. The other isotopes are synthetic in nature and have their mass numbers ranging from 256 to 270.
- The metal is produced in small amounts artificially. The bombardment of it can make many isotopes of it with the Heavy Ion Linear Accelerator.