Dubnium elements

Distillation, azeotropes, 6-177 to 195 Divergence, definition, A-68 to 74 DSC, definition, 12-1 to 4 DTA, definition, 12-1 to 4 Dubnium (element 105), 4-1 to 42,11-56 to 253 Dysprosium see also Elements electrical resistivity, 12-39 to 40 electron configuration, 1-18 to 19 heat capacity, 4-135 history, occurrence, uses, 4-1 to 42 ionization energy, 10-203 to 205 isotopes and their properties, 11-56 to 253 magnetic susceptibility, 4-142 to 147 molten, density, 4-139 to 141... 

The discoveries of all three of these elements were made at the beginning of the nineteenth century and were marked by initial uncertainty and confusion due, in the case of the heavier pair of elements, to the overriding similarity of their chemistries. (See p. 1282 for element 105, dubnium.)... 

Dubnium - the atomic number is 105 and the chemical symbol is Db. The name derives from the location of the Russian research center, the Joint Institute for Nuclear Research lab in Dubna , Russia. The first synthesis of this element is jointly credited to the American scientific team at the University of California in Berkeley, California imder Albert Ghiorso and the Russian scientific team at the JINR (Joint Institute for Nuclear Reactions) lab in Dubna, Russia, imder Georgi N. Flerov in 1970. The longest half-life associated with this unstable element is 34 second Db. 

ORIGIN OF NAME Unnilquadium follows the transitional naming system of lUPAC but originally was named "hahnium" by the Berkeley group in honor of Otto Hahn, who discovered nuclear fission. The American Chemical Society endorsed the name "hahnium" for element 105, but as the Berkeley group continued its work and more isotopes of Q Unp were formed, the lUPAC changed the name "hahnium" to "dubnium" after the city Dubna, Russia, where the first isotopes of unnilpentium were formed. 

After evidence of the formation of unnilpentium in 1970 by the Berkeley team, the American Chemical Society (ACS) changed the name Unp to hahnium. To settle the confusing claims, the lUPAC recommended that scientists from the Russian and Berkeley groups get together to review and confirm conflicting data. This cooperative venture was never implemented. In 1997 the lUPAC decided to change the name hahnium (j Ha) to dubnium ( jj Db) after the location of the Russian nuclear research lab that first produced the new element. Dubnium is the name by which it is known by today. 

No compounds are pubhshed for unnilpentium (dubnium), but it could possibly form compounds similar to its homologue element 71, tantalum, in group 5. 

The hazards of dubnium are similar to all radioactive heavy metals of the transactinide series, but there is no threat to the public given that such a small amount of the element is produced and exists. 

The two scientists then traced the very short decay sequence of the three Une-266 atoms as they decayed into element 107 (unnilseptium or bohrium) and element number 105 (unnil-pentium or dubnium). The decay sequence is as follows ... 

Many chemists go to school for years and earn the top college degree before they make important discoveries in the lab, but James Andrew Harris took a different path. Harris graduated from college with a basic degree in chemistry, but then served in the Army and worked in a company lab before joining the team that discovered the transuranium elements rutherfordium and dubnium. 

Harris s talents were finally noticed at the University of California s Lawrence Radiation Laboratory, where he helped prepare some of the elements used in the discovery of rutherfordium and dubnium. Although he never finished his studies, his old college gave him a doctorate—the highest degree in science—to honor his work on the new elements. 

Tiirler, A. Gas Phase Chemistry of the Transactinide Elements Rutherfordium, Dubnium, and Seaborgium , in Habilitation Thesis, Bern University (1999). 

The known chemical properties of superheavy elements are presented and discussed in Chapter 5 and 7 based upon experimental results obtained from the liquid phase and from the gas phase, respectively. It is quite natural that there is a large body of information on group-4 element 104, rutherfordium, and group-5 element 105, dubnium, which are now under investigation for three decades. However, recent detailed studies demonstrate that these... 

Two names were proposed for element 104, kurtchatovium (in honour of the Russian physicist Kurtchatov) by the Dubna group and rutherfordium (in honour of Rutherford) by the Berkeley group. The Dubna group (Flerov et al., 1968) was also the first to announce the discovery of element 105 (dubnium) by bombardment of 243 Am with 22]Sfe However, the assignment of the mass numbers 260 or 261 was not possible unambiguously. In Berkeley, element 105 was produced by the reactions (Ghiorso et al., 1970) ... 

At this time, to name an element a researcher or team of researchers must be certified by lUPAC as the discoverers of that element, at which time they are free to name the compound. The elements 104-109 were subject to a naming controversy. The originally proposed names of these elements by lUPAC were, in order, dub-nium, joliotium, rutherfordium, bohrium, hahnium, and meiterium. The names which appear on the current periodic table are, in order, rutherfordium (Rf), dubnium (Db), seaborgium, bohrium (Bh), hassium (Hs), and meitnerium (Mt). 

The half life of most transfermium isotopes is only a few seconds or less. The half life of dubnium-260, for example, is 1.6 seconds. That means that half of the atoms in a sample will break down in 1.6 seconds and change to some other element. The short half lives of the transfermium isotopes make them hard to study. They tend to break down almost as soon as they are formed. Scientists have very litde time to observe them. 

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