Tantalum naming

It was assumed that tantalum, when added to the melt in the form of potassium heptafluorotantalate, K2TaF7, interacts with KF or KC1 to form a compound with an increased tantalum coordination number of up to eight. The compound is present in the melt in its dissociated form, yielding potassium ions and octa-coordinated complexes of tantalum, namely TaFg3 or TaF7Cl3. ... 

Despite the facts (a) that the figures for individual determinations differed by several whole units and (b) that the results as a whole were obviously discordant, Marignac s work formed the basis for the accepted atomic weight of tantalum (namely, 183) for forty years. The suitability of the double fluorides for use in the determination of the atomic weight has been questioned.9... 

Only one sulphide of tantalum, namely, the disulphide, TaS2, is known, and this is prepared by a dry method. Hydrogen sulphide does not precipitate any sulphides when passed into a solution of a tantal te, nor does reduction take place it is without appreciable action on tantalum pentoxide even at 1200° C.s... 

Nb niobium, 41, 1801 after Niobe, daughter of Tantalus in Greek mythology niobium was once thought to be identical with tantalum, named after Tantalus, until about 1844. Its original and long-time alternate name was Columbium, with the symbol Cb. 

Niobium Nb 41 92.91 1801 Charles Hatchett (GB) Gr. Niobe, daughter of Tantalus (niobium was considered identical to tantalum, named after Tantalus, until 1884)... 

Niobium, discovered by Hatchett ia 1801, was first named columbium. In 1844, Rosed thought he had found a new element associated with tantalum (see Tantalum AND tantalum compounds). He called the new element niobium, for Niobe, daughter of Tantalus of Greek mythology. In 1949, the Union of Pure and Apphed Chemistry setded on the name niobium, but in the United States this metal is stiU known also as columbium. Sometimes called a rare metal, niobium is actually more abundant in the earth s cmst than lead. 

In the same year that del Rio found his erythronium, C. Hatchett examined a mineral which had been sent to England from Massachusetts and had lain in the British Museum since 1753. From it he isolated the oxide of a new element which he named columbium, and the mineral columbite, in honour of its country of origin. Meanwhile in Sweden A. G. Ekeberg was studying some Finnish minerals and in 1802 claimed to have identified a new element which he named tantalum because of the difficulty he had had in dissolving the mineral in acids. It was subsequently thought that the two elements were one and the same, and this view persisted until at least 1844 when H. Rose examined a columbite sample and showed that two distinct elements were involved. 

One was Ekeberg s tantalum and the other he called niobium (Niobe was the daughter of Tantalus). Despite the chronological precedence of the name columbium, lUPAC adopted niobium in 1950, though columbium is still sometimes used in US industry. Impure niobium metal was first isolated by C. W. Blomstrand in 1866 by the reduction of the chloride with hydrogen, but the first pure samples of metallic niobium and tantalum were not prepared until 1907 when W. von Bolton reduced the fluorometallates with sodium. 

Table 55 presents the results discussed above. Fluoride melts containing tantalum contain two types of complex ions, namely TaF6 and TaF72 . The equilibrium between the complexes depends on the concentration of fluoride ions in the system, but mostly upon the nature of the outer-sphere cations. The complex ionic structure of the melts can be adjusted by adding cations with a certain polarization potential. For instance, the presence of low polarization potential cations, such as cesium, leads primarily to the formation of TaF72 complexes, while the addition of cations with relatively high polarization potentials, such as lithium or sodium, shifts the equilibrium towards the formation of TaF6 ions. 

As was discussed in Chapter 4, tantalum and niobium dissolve in fluorine-containing solutions in the form of complex fluoride ions of two types, namely TaF727TaF6" and NbOF527NbF6 [61, 155, 171, 291]. The equilibrium between the complexes depends on the acidity of the solution and can be represented schematically as shown in Equations (139) and (140) for tantalum and niobium, respectively ... 

The main difference between the methods is usually related to the first step, namely fluorine substitution and precipitation of tantalum or niobium compounds. 

Potassium heptafluorotantalate, K2TaF7, or as it is called by its commercial name K-salt, is a starting material for tantalum metal production. K-salt is produced by adding potassium fluoride, KF, or potassium chloride, KC1, to a tantalum strip solution that results from a liquid-liquid extraction process. In order to prevent hydrolysis and co-precipitation of potassium oxyfluoro-tantalate, a small excess of HF is added to the solution [24]. Another way to avoid the possible formation and co-precipitation of oxyfluoride phases is to use potassium hydrofluoride, KHF2, as a potassium-containing agent. The yield of the precipitation depends mostly on the concentration of the potassium-containing salt and is independent of the HF concentration [535]. 

Name derived from Niobe, daughter of Tanatalus (Greek mythology) niobium and tantalum always occur together... 

The mechanism of cathodic luminescence is distinctly different from other ECL systems. Light is emitted from oxide-covered, so-called valve metal, electrodes, namely aluminium and tantalum, during the reduction of peroxodisulfate, hydrogen peroxide, or oxygen, in aqueous solution, at relatively low potentials (<10 V). The mechanism involving persulfate, for example, is as follows. A conduc-... 

Tantalum (Ta, [Xe]4/145J36x2), name and symbol after the Greek mythological hero Tantalus. Discovered (1802) by Anders Gustav Ekeberg. 

Tantalum - the atomic number is 73 and the chemical symbol is Ta. The name derives from the Greek Tantalos , for the mythological character who was banished to Hades, the region of lost souls where he was placed up to his chin in water, which receded whenever he tried to drink it... 

However, the story does not end there. It was not until 1844 when Heinrich Rose (1795-1864) rediscovered the element by producing two similar acids from the mineral niobic acid and pelopic acid. Rose did not reahze he had discovered the old columbium, so he gave this new element the name niobium. Twenty years later, Jean Charles Galissard de Marignac (1817—1894) proved that niobium and tantalum were two distinct elements. Later, the Swedish scientist Christian Wilhelm Blomstrand (1826—1899) isolated and identified the metal niobium from its similar twin, tantalum. 

ORIGIN OF NAME Tantalum was named after Tantalus, who was the father of Niobe, the queen of Thebes, a city in Greek mythology. (Note The element tantalum was originally confused with the element nobelium.)... 

Tantalum was discovered by the Swedish chemist Anders Ekeberg in 1802, although for a long time after his discovery many chemists believed tantalum and niobium were the same element. In 1866, Marignac developed a fractional crystallization method for separation of tantalum from niobium. Ekeberg named the element in honor of Tantalus, who was Niobe s father in Greek mythology. 

Ekeberg found the yttrotantalite in the same place as the gadolinite at Ytterby, Sweden. He found that both contained a hitherto unknown metal. Because it had been such a tantalizing task to trace it down, Ekeberg named it tantalum (32). 

Although niobic and tantalic acids are extremely difficult to separate, Marignac finally succeeded, not only in separating them, but also in showing that niobium is both tri- and pentavalent, whereas tantalum always has a valence of five. The separation is based on the insolubility of potassium fluotantalate in comparison with potassium fluo-oxyniobate (12, 20). In the United States the element discovered by Hatchett used to be known as columbium, but in Europe most chemists prefer to use the name niobium which Heinrich Rose gave it. 

To remove radium and other radioactive constituents from pitchblende, Hahn and Meitner treated pulverized pitchblende repeatedly and for long periods of time with hot concentrated nitric acid. From the insoluble siliceous residue they separated a new radioactive substance, which they called protoactinium. This name has subsequently been shortened to protactinium. When they added a little tantalum salt to a solution containing protactinium, the reactions of the new substance so closely resembled those of tantalum that Hahn and Meitner were unable to separate the two substances (118). Since tantalum is not radioactive, the protactinium could thus be obtained free from other radioelements. Since protactinium is not an isotope of tantalum, it should be possible to separate them from each other (119). By working up large quantities of rich pitchblende residues from the Quinine Works at Braunschweig, Hahn and Meitner were able to extract more active preparations of the new element (49). 

Tantalic Acid and Tantalates. Tantalic acid [75397-94-3], Ta2Os H20, is the name of the white insoluble precipitate formed by hydrolysis of alkali hydroxide or alkali carbonate fusions containing tantalum, or by adding ammonia to an acidic solution containing tantalum ions. Tantalic acid is characterized by a high surface acidity, affording it potential use as a catalyst. 

Recently, there has been a growing interest into niobium- and tantalum-containing molecular sieves. The introduction of niobium into mesoporous molecular sieves has been studied by Ziolek et al [3,4], while Antonelli and Ying reported the synthesis of mesoporous niobium oxide [5], The synthesis and characterization of niobium- and tantalum-containing silicalite-1 (NbS-1 and TaS-1) was published recently [6,7,8] and some evidence has been presented for isomorphous substitution [6,8] of Nb and Ta into the silicalite-1 framework. The synthesis of NbS-2 (MEL) [9] and a new molecular sieve named NbAM-11 have been reported as well [10],... 

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