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Tantalum

What is tantalum?

Tantalum is a chemical element or rare, hard, blue-gray, lustrous transition metal of Group 5 (VB) of the periodic table with the symbol Ta and atomic number 73. It is used for manufacturing capacitors and filaments 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.

Properties of tantalum

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. Some important physical and chemical properties of tantalum are given below the table,

Tantalum chemical element or transition metal symbol, properties, production, facts, uses and position on the periodic table

Properties of Tantalum
Atomic number 73
Electron per shell 2, 8, 18, 32, 11, 2
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
Electronic configuration [Xe] 4f14 5d3 6s2
Block d-block
Period period 6
Group group 5
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 or state +5
Electronegativity Pauling scale – 1.50
Ionization energy (kJ/mol) 1st 2nd
761 1500

Tantalum on the periodic table

The element is placed in group-5 of the periodic table with vanadium and niobium. The element has [Xe] 4f14 5d3 6s2 valence shell electronic configuration. Therefore, tantalum is placed with the d-block element or transition metal.

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

Who discovered tantalum?

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 Nb and Ta was obtained in 1907 (Werner von Bolton) by the reduction of flurometallates by sodium.

Where is tantalum found?

Tantalum is 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 are used for the production of different types of short lives isotopes like 8Li, 80Rb, and 180Y.

Production process

The mineral of tantalum is fused with potassium carbonate and extracted with water. The insoluble hydroxide of iron and manganese is 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.

Facts about tantalum

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

Chemical compounds

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.

Complexes of tantalum

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

Tantalum compounds
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 complexes of tantalum

It 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 is 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 Ta. Therefore, the metal used to coating other metals and a high capacitance can be achieved. Due to the small size and weight, tantalum capacitors are 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 are 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, it is used for making chemical reaction vessels and pipes for corrosive liquids. Tantalum has been used as an electrode in neon lights, AC/DC rectifiers.