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Tantalum

Information, Properties, Compounds, Uses

Tantalum Element in Periodic Table

Tantalum (Ta) is a chemical element or rare, hard, blue-gray, lustrous transition metal of Group 5 (VB) of the periodic table used for manufacturing capacitors and filament in lamps. It has high density, extremely high melting point, and excellent corrosion resistance properties. The high melting and boiling point of tantalum suggests that the participation of a large number of d-electrons in metallic bonding. The element is relatively unreactive and resistant to all acids except hydrofluoric at ordinary temperatures.

Position of transition metal or chemical element Tantalum in the periodic table

Pure tantalum forms a body-centered cubic crystal lattice. It has similar chemical properties to that of niobium. Today, tantalum capacitors are used in different types of electronic devices like mobile phones, DVD players, video game systems, and computers. The atomic number of the element is 73 and the valence shell electronic configuration [Xe] 5d3 6s2. Some important physical and chemical properties of tantalum are given below the table.

Tantalum element chemical symbol and periodic table properties

Properties of Tantalum
Atomic number 73
Atomic weight 180.947
Melting point 3290 K ​(3017 °C, ​5463 °F)
Boiling point 5731 K ​(5458 °C, ​9856 °F)
Density 16.69 g/cm3
Molar heat capacity 25.36 J mol-1K-1
Electrical resistivity 131 nΩ·m
Atomic radius 146 pm
Covalent radius 170±8 pm
Chemical properties
Oxidation number +5
Electronegativity Pauling scale – 1.50
Ionization energy 1st – 761 kJ/mol
2nd – 1500 kJ/mol

History and Occurrence

In 1802, Anders Ekeberg discovered an oxide of a new metallic element in Sweden that could not be dissolved in any acids. He named the metal tantalum after tantalus, a villain from Greek mythology. One year earlier, Charles Hatchett had discovered columbium (now called niobium) from a mineral of North America. In 1846 by the German chemist, Heinrich Rose established that the chemical elements columbium and tantalum were chemically very similar and always occurred together. He renamed colombium as niobium (Niobe was the daughter of Tantalus), which was adopted by IUPAC in 1950.

In 1864 by Christian Wilhelm Blomstrand and Henri Etienne Sainte-Claire Deville observed the solubilities of potassium flrorotantalate and fluroniobate in hydrogen fluoride. The pure form of niobium and tantalum was obtained in 1907 (Werner von Bolton) by the reduction of flurometallates by sodium.

Tantalum found in the earth’s crust to the extent of 1.7 ppm. Owing to the great chemical similarities with niobium, it always occurs with niobium. The main mineral of the metal is tantalate with the chemical composition (Fe, Mn) M2O6, M = Nb, Ta. It is obtained as a byproduct in the extraction of tin in Malaysia and Nigeria.

Isotopes

Tantalum has two natural isotopes like 180mTa (m = metastable) and 181Ta with the occurrence of 0.012 percent and 99.988 percent respectively. These isotopes are obtained generally by the isomeric transition, beta decay or electron capture nuclear reaction. The radioactive half-life of these radioactive isotopes can not observe experimentally. These isotopes used for the production of different types of short lives isotopes like 8Li, 80Rb, and 180Y.

Production

The mineral of tantalum fused with potassium carbonate and extracted with water. The insoluble hydroxide of iron and manganese are largely eliminated by the process. The aqueous extract containing K3NbO4 and K3NbO4 is treated with carbon dioxide to precipitate pentaoxides of the metals. It dissolved in concentrated hydrogen fluoride from more solube K2NbOF5 and less soluble K2TaF7. These are separated by fractional crystallization.

Reduction of K2NbOF5 by aluminum gives niobium. Electrolysis of molten K2TaF7 gives tantalum. Now a day, the metals are produced by the solvent extraction process.

Chemistry and Chemical Compounds of Tantalum

The effect of lanthanide construction makes the metallic and ionic radii of niobium and tantalum the same. The chemistry of these two metals very similar but the ground electronic configurations are different. The stable and common oxidation state of tantalum is +5 (V) but it shows a wide range of lower oxidation states. The lower oxidation compounds of tantalum relatively more stable than zirconium and hafnium.

The transition element shows little cationic chemistry and forms a large number of anionic species. The halides and oxohalides are the most important chemical compounds of tantalum. They are mostly in volatile nature. A large number of metal atom cluster compounds are known in the lower oxidation state of the metal.

Complex Compounds

The main chemical complex in the different oxidation state of tantalum is proxy and halo complexes. The oxidation state, geometry, coordination number, and examples of such complexes given below the table.

Complex Compounds of Tantalum
Oxidation state Co-ordination number Geometry Examples
+5 (V) 6 octahedral [TaF6]; [TaCl5, SMe2]
trigonal prism [Ta(S2C6H4)3]
+4 (IV) 6 octahedral [TaCl6]-2; [TaBr6]-2
8 dodecahedral [TaCl4(diars)2]
+3 (III) 6 octahedral [Ta2Cl6(SMe2)3]

Organometallic Compounds

Tantalum has extensive chemistry with organic compounds that involving Ta-C σ-bonds and η-C2H5 bonds. The methyl forms of the metal are stable compounds prepared by reduction of the penta-halides in ether medium. TaMe5 may explode spontaneously at room temperature. The alkyls are Lewis bases that react with natural ligands or forming anions.

Uses of Tantalum

  • Tantalum used widely for the production of electronic components, mainly in capacitors, high-power resistors, and filament in Lamps. An insulating or dielectric oxide layer forms on the surface of tantalum. Therefore, the metal used to coating other metals and a high capacitance can be achieved. Due to the small size and weight, tantalum capacitors used in mobile or portable telephones, laptops, automotive electronics, and cameras.
  • Tantalum is highly inert to the body fluids and used or suitable for making skull plates, screws, and wires used in orthopedic surgery.
  • It is also used for the production of different types of alloys that have high melting points, strength, and ductility. Tantalum alloys used mainly in turbine blades, rocket nozzles, and nose caps for supersonic aircraft.
  • It is highly inert towards most acids and alkalies except hydrofluoric acid and hot sulfuric acid. Therefore, the metallic tantalum used for making chemical reaction vessels and pipes for corrosive liquids. Tantalum has used as an electrode in neon lights, AC/DC rectifiers.