It is part of the refractory metals group, which are widely used as minor components in alloys. Although Ta occurs as various minerals, it is conveniently represented as the pentoxide, since most oxides of tantalum(V) behave similarly under these conditions. Tantalum (Ta) has a very high melting point (2996°C), exceeded only by … Orthorhombic. The noble metals tend to be soft as well. The alpha phase is relatively ductile and soft; it has body-centered cubic structure (space group Im3m, lattice constant a = 0.33058 nm), Knoop hardness 200–400 HN and electrical resistivity 15–60 µΩ⋅cm. Heat exchanging coils for the steam heating of hydrochloric acid are made from tantalum. [28] In basic media, Ta can be solubilized due to the formation of polyoxotantalate species. Luster. Bulk tantalum is almost entirely alpha phase, and the beta phase usually exists as thin films[22] obtained by magnetron The Wodgina mine was reopened in January 2011 after mining at the site was suspended in late-2008 due to the global financial crisis. [25], Tantalum has been examined theoretically as a "salting" material for nuclear weapons (cobalt is the better-known hypothetical salting material). Organotantalum compounds include pentamethyltantalum, mixed alkyltantalum chlorides, alkyltantalum hydrides, alkylidene complexes as well as cyclopentadienyl derivatives of the same. �Y��������iK۶i[o½���K��k��1rﶍ_��t�k�`��6���|;�?0���n۷s�����Ż��u�9,b|��.`3KL�%�6�(2�� 2���\����"���E��Ht���ğ{�g��X��,F�%1 ������X�F���0n�hk��h������. These equations are simplified: it is suspected that bisulfate (HSO4−) and chloride compete as ligands for the Nb(V) and Ta(V) ions, when sulfuric and hydrochloric acids are used, respectively. The anion [TaF7]2- is used for its separation from niobium. Color. [7][8] One year earlier, Charles Hatchett had discovered columbium (now niobium),[9] and in 1809 the English chemist William Hyde Wollaston compared its oxide, columbite with a density of 5.918 g/cm3, to that of tantalum, tantalite with a density of 7.935 g/cm3. It is also the rarest primordial isotope in the Universe, taking into account the elemental abundance of tantalum and isotopic abundance of 180mTa in the natural mixture of isotopes (and again excluding radiogenic and cosmogenic short-lived nuclides). iron, manganese, titanium, zirconium), which remain in the aqueous phase in the form of their fluorides and other complexes. He concluded that the two oxides, despite their difference in measured density, were identical and kept the name tantalum. "[20], For decades, the commercial technology for separating tantalum from niobium involved the fractional crystallization of potassium heptafluorotantalate away from potassium oxypentafluoroniobate monohydrate, a process that was discovered by Jean Charles Galissard de Marignac in 1866. Tantalum is a much more rare metal consisting … [16] De Marignac was the first to produce the metallic form of tantalum in 1864, when he reduced tantalum chloride by heating it in an atmosphere of hydrogen. [73] Some values on dissolved concentrations in oceans have been published, but they are contradictory. Oxides of tantalum in lower oxidation states are numerous, including many defect structures, and are lightly studied or poorly characterized. Tantalum rings are slightly more expensive than titanium or tungsten rings, and for good reason. Tantalum, always together with the chemically similar niobium, occurs in the mineral groups tantalite, columbite and coltan (a mix of columbite and tantalite, though not recognised as a separate mineral species). This is generally carried out near the mine site. [73] Values in soils are close to 1 ppm and thus to UCC values. Values in freshwaters fare little better, but, in all cases, they are probably below 1 ng L−1, since ‘dissolved’ concentrations in natural waters are well below most current analytical capabilities. [6] Tantalite (Fe, Mn)Ta2O6 is the most important mineral for tantalum extraction. [68] Because tantalum is a non-ferrous, non-magnetic metal, these implants are considered to be acceptable for patients undergoing MRI procedures. Alloyed with other metals, it is also used in making carbide tools for metalworking equipment and in the production of superalloys for jet engine components, chemical process equipment, nuclear reactors, missile parts, heat exchangers, tanks, and vessels. A tantalum-tellurium alloy forms quasicrystals. Tantalum is a chemical element with the symbol Ta and atomic number 73. K2[TaF7] can be converted to metallic tantalum by reduction with sodium, at approximately 800 °C in molten salt.[56]. [29], Tantalum pentoxide (Ta2O5) is the most important compound from the perspective of applications. [71] The latest value for upper crust concentration is 0.92 ppm, and the Nb/Ta(w/w) ratio stands at 12.7. [42][43], It is estimated that there are less than 50 years left of tantalum resources, based on extraction at current rates, demonstrating the need for increased recycling. In contrast, many transition metals rank exceptionally high on the Mohs scale. Tantalum is dark (blue-gray),[21] dense, ductile, very hard, easily fabricated, and highly conductive of heat and electricity. The beta phase is metastable and converts to the alpha phase upon heating to 750–775 °C. This conclusion was disputed in 1846 by the German chemist Heinrich Rose, who argued that there were two additional elements in the tantalite sample, and he named them after the children of Tantalus: niobium (from Niobe, the goddess of tears), and pelopium (from Pelops). Tantalum was discovered in Sweden in 1802 by Anders Ekeberg, in two mineral samples – one from Sweden and the other from Finland. The metal is highly biocompatible[67] and is used for body implants and coatings, therefore attention may be focused on other elements or the physical nature of the chemical compound. This method has been supplanted by solvent extraction from fluoride-containing solutions of tantalum.[14]. [57], All welding of tantalum must be done in an inert atmosphere of argon or helium in order to shield it from contamination with atmospheric gases. Since it resists attack by body fluids and is nonirritating, tantalum is widely used in making surgical instruments and implants. Pollution linked to human use of the element has not been detected. [27], Tantalum forms compounds in oxidation states −III to +V. When tantalum enrichment is observed, it is probably due to loss of more water-soluble elements in aerosols in the clouds.[75]. First, the mineral is crushed and concentrated by gravity separation. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 5 mg/m3 over an 8-hour workday and a short-term limit of 10 mg/m3. However, radioactivity of this nuclear isomer has never been observed, and only a lower limit on its half-life of 2.0 × 1016 years has been set.

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