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| - Tantalum (symbol Ta) is a chemical element, a transition metal with atomic number 73 on the periodic table.
- The metal is renowned for its resistance to corrosion by acids; in fact, at temperatures below 150 °C tantalum is almost completely immune to attack by the normally aggressive aqua regia. It can be dissolved with hydrofluoric acid or acidic solutions containing the fluoride ion and sulphur trioxide, as well as with a solution of potassium hydroxide. Tantalum's high melting point of 3017 °C (boiling point 5458 °C) is exceeded only by tungsten and rhenium for metals, and carbon.
- Tantalum is a chemical element with symbol Ta and atomic number 73. Previously known as tantalium, its name comes from Tantalus, a hero from Greek mythology. Tantalum is a rare, hard, blue-gray, lustrous transition metal that is highly corrosion-resistant. It is part of the refractory metals group, which are widely used as minor components in alloys. The chemical inertness of tantalum makes it a valuable substance for laboratory equipment and a substitute for platinum. Tantalum is also used for medical implants and bone repair. Its main use today is in tantalum capacitors in electronic equipment such as mobile phones, DVD players, video game systems and computers. Tantalum, always together with the chemically similar niobium, occurs in the minerals tantalite, columbite and coltan (a mix of
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| abstract
| - Tantalum (symbol Ta) is a chemical element, a transition metal with atomic number 73 on the periodic table.
- Tantalum is a chemical element with symbol Ta and atomic number 73. Previously known as tantalium, its name comes from Tantalus, a hero from Greek mythology. Tantalum is a rare, hard, blue-gray, lustrous transition metal that is highly corrosion-resistant. It is part of the refractory metals group, which are widely used as minor components in alloys. The chemical inertness of tantalum makes it a valuable substance for laboratory equipment and a substitute for platinum. Tantalum is also used for medical implants and bone repair. Its main use today is in tantalum capacitors in electronic equipment such as mobile phones, DVD players, video game systems and computers. Tantalum, always together with the chemically similar niobium, occurs in the minerals tantalite, columbite and coltan (a mix of columbite and tantalite). Tantalum is a rare metal, comprising just 8×10−9% of the universe, making it fifteen times less abundant in the universe than gold (which makes up 6×10−8%). Tantalum also comprises just 1.5×10−4% of the earth's crust, making it more abundant than other metals in the sixth period, such as rhenium (abundance 2.6×10−7%), osmium (abundance 1.8×10−7%), or iridium (abundance 4×10−8%), but not as abundant as barium (abundance 3.4×10−2%).
- The metal is renowned for its resistance to corrosion by acids; in fact, at temperatures below 150 °C tantalum is almost completely immune to attack by the normally aggressive aqua regia. It can be dissolved with hydrofluoric acid or acidic solutions containing the fluoride ion and sulphur trioxide, as well as with a solution of potassium hydroxide. Tantalum's high melting point of 3017 °C (boiling point 5458 °C) is exceeded only by tungsten and rhenium for metals, and carbon. It is able to form oxides with the oxidation states +5 (Ta2O5) and +4 (TaO2), The most stable oxidation state is +5, tantalum pentoxide. Tantalum pentoxide is the starting material for several tantalum compounds. The compounds are created by dissolving the pentoxide in basic hydroxide solutions or by melting it in another metal oxide. Such examples are lithium tantalate (LiTaO3) and lanthanum tantalate (LaTaO4). In the lithium tantalate, the tantalate ion TaO−3 does not occur; instead, this part of the formula represents linkage of TaO7−6 octahedra to form a thensional perovskite framework; te contains lone TaO3−4 tetrahedral The fluorides of tantalum can be used for its separation from niobium. Tantalum forms halogen compounds in the oxidation states of +5, +4, and +3 of the type TaX5, TaX4aX3, although multi core complexes and substoichiometric compounds are also known. Tantalum pentafluoride (TaF5) is a white solid with a melting point of 97.0 °C and tantalum pentachloride (TaCl5) is a white solid with a melting point of 247.4 °C. Tantalum pentachloride is hydrolysed by water and reacts with additional tantalum at elevated temperatures by forming the black and highly hygroscopic tantalum tetrachloride (TaCl4). While the trihalogen compounds can be obtained by reduction of the pentahalogenes with hydrogen, the dihalogen compounds do not exist. A tantalum-tellurium alloy forms quasicrystals. Tantalum c with oxidation states as low as -1 have been reported. Like most of the other refractory metals, the hardest known compounds are the stable nitrides and carbides. Tantalum carbide, TaC, like the more commonly used tungsten carbide, is a very hard ceramic that is used in cutting tools. Tantalum (III) nitride is used as a thin film insulator in some microelectronic fabrication processes. There are two tantalum aluminides, TaAl3 and Ta3Al. These are stable, refractory, and reflective, and they have been proposed as coatings for use in infrared wave mirrors.
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