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Tantalum
From Wikipedia, the free encyclopedia
Jump to: navigation, search
hafnium ← tantalum → tungsten
Nb
↑
Ta
↓
Db
73TaPeriodic table
Appearance
gray blue
General properties
Name, symbol, number tantalum, Ta, 73
Element category transition metal
Group, period, block 5, 6, d
Standard atomic weight 180.94788 g·mol−1
Electron configuration [Xe] 4f14 5d3 6s2
Electrons per shell 2, 8, 18, 32, 11, 2 (Image)
Physical properties
Phase solid
Density (near r.t.) 16.69 g·cm−3
Liquid density at m.p. 15 g·cm−3
Melting point 3290 K, 3017 °C, 5463 °F
Boiling point 5731 K, 5458 °C, 9856 °F
Heat of fusion 36.57 kJ·mol−1
Heat of vaporization 732.8 kJ·mol−1
Specific heat capacity (25 °C) 25.36 J·mol−1·K−1
Vapor pressure
P/Pa 1 10 100 1 k 10 k 100 k
at T/K 3297 3597 3957 4395 4939 5634
Atomic properties
Oxidation states 5, 4, 3, 2, -1 (mildly acidic oxide)
Electronegativity 1.5 (Pauling scale)
Ionization energies 1st: 761 kJ·mol−1
2nd: 1500 kJ·mol−1
Atomic radius 146 pm
Covalent radius 170±8 pm
Miscellanea
Crystal structure body-centered cubic
Magnetic ordering paramagnetic[1]
Electrical resistivity (20 °C) 131 nΩ·m
Thermal conductivity (300 K) 57.5 W·m−1·K−1
Thermal expansion (25 °C) 6.3 µm·m−1·K−1
Speed of sound (thin rod) (20 °C) 3400 m/s
Young's modulus 186 GPa
Shear modulus 69 GPa
Bulk modulus 200 GPa
Poisson ratio 0.34
Mohs hardness 6.5
Vickers hardness 873 MPa
Brinell hardness 800 MPa
CAS registry number 7440-25-7
Most stable isotopes
Main article: Isotopes of tantalum
iso NA half-life DM DE (MeV) DP
177Ta syn 56.56 h ε 1.166 177Hf
178Ta syn 2.36 h ε 1.910 178Hf
179Ta syn 1.82 a ε 0.110 179Hf
180Ta syn 8.125 h ε 0.854 180Hf
β− 0.708 180W
180mTa 0.012% >1.2×1015 y
(not observed) ε 0.929 180Hf
β− 0.783 180W
IT 0.075 180Ta
181Ta 99.988% 181Ta is stable with 108 neutrons
182Ta syn 114.43 d β− 1.814 182W
183Ta syn 5.1 d β− 1.070 183W
This box: view • talk • edit
Tantalum (pronounced /ˈtæntələm/, TAN-təl-əm) (formerly tantalium /tænˈtæliəm/, tan-TAL-ee-əm) is a chemical element with the symbol Ta and atomic number 73. A rare, hard, blue-gray, lustrous transition metal, tantalum is highly corrosion resistant and occurs naturally in the mineral tantalite, always together with the chemically similar niobium. It is part of the refractory metals group, which are widely used as minor component in alloys. The chemical inertness of tantalum makes it a valuable substance for laboratory equipment and a substitute for platinum, but its main use today is in tantalum capacitors in electronic equipment.
Contents [hide]
1 History
2 Characteristics
2.1 Physical
2.2 Chemical
2.3 Isotopes
2.4 Occurrence
3 Production
4 Applications
4.1 Electronics
4.2 Alloys
4.3 Other uses
5 Precautions
6 References
7 External links
[edit] History
Tantalum was discovered in Sweden in 1802 by Anders Ekeberg. One year earlier, Charles Hatchett had discovered the element columbium.[2] In 1809, the English chemist William Hyde Wollaston compared the oxides derived from both columbium—columbite, with a density 5.918 g/cm3, and tantalum—tantalite, with a density 7.935 g/cm3, and concluded that the two oxides, despite their difference in measured density, were identical. He decided to keep the name tantalum.[3] After Friedrich Wöhler confirmed these results, it was thought that columbium and tantalum were the same element. 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).[4][5] The supposed element "pelopium" was later identified as a mixture of tantalum and niobium, and it was found that the niobium was identical to the columbium already discovered in 1801 by Hattchet.
The differences between tantalum and niobium were demonstrated unequivocally in 1864 by Christian Wilhelm Blomstrand,[6] and Henri Etienne Sainte-Claire Deville, as well as by Louis J. Troost, who determined the empirical formulas of some of their compounds in 1865[6][7]. Further confirmation came from the Swiss chemist Jean Charles Galissard de Marignac,[8] in 1866, who all proved that there were only two elements. These discoveries did not stop scientists from publishing articles about the so-called ilmenium until 1871.[9] 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.[10] Early investigators had been only able to produce impure tantalum, and the first relatively pure ductile metal was produced by Werner von Bolton in 1903. Wires made with metallic tantalum were used for light bulb filaments until tungsten replaced it in widespread use.[11]
The name tantalum was derived from the name of the mythological Tantalus, the father of Niobe in Greek mythology. In the story, he had been punished after death by being condemned to stand knee-deep in water with perfect fruit growing above his head, both of which eternally tantalized him. (If he bent to drink the water, it drained below the level he could reach, and if he reached for the fruit, the branches moved out of his grasp.)[12] Ekeberg wrote "This metal I call tantalum … partly in allusion to its incapacity, when immersed in acid, to absorb any and be saturated."[13]
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. This method has been supplanted by solvent extraction from fluoride-containing solutions of tantalum.[7]
The mining of coltan, a tantalum ore, in the violently conflicted regions of the Democratic Republic of the Congo has raised ethical questions and human rights problems, and the question of endangering wildlife.[14][15][16]
http://popup.lala.com/popup/432627047847212804
Ole History Student/Run for the Hills
is doing the DANCE
Pretty soon I'll be TUNGSTEN level... maybe I'll buy some gold paint!
Tantalum
From Wikipedia, the free encyclopedia
Jump to: navigation, search
hafnium ← tantalum → tungsten
Nb
↑
Ta
↓
Db
73TaPeriodic table
Appearance
gray blue
General properties
Name, symbol, number tantalum, Ta, 73
Element category transition metal
Group, period, block 5, 6, d
Standard atomic weight 180.94788 g·mol−1
Electron configuration [Xe] 4f14 5d3 6s2
Electrons per shell 2, 8, 18, 32, 11, 2 (Image)
Physical properties
Phase solid
Density (near r.t.) 16.69 g·cm−3
Liquid density at m.p. 15 g·cm−3
Melting point 3290 K, 3017 °C, 5463 °F
Boiling point 5731 K, 5458 °C, 9856 °F
Heat of fusion 36.57 kJ·mol−1
Heat of vaporization 732.8 kJ·mol−1
Specific heat capacity (25 °C) 25.36 J·mol−1·K−1
Vapor pressure
P/Pa 1 10 100 1 k 10 k 100 k
at T/K 3297 3597 3957 4395 4939 5634
Atomic properties
Oxidation states 5, 4, 3, 2, -1 (mildly acidic oxide)
Electronegativity 1.5 (Pauling scale)
Ionization energies 1st: 761 kJ·mol−1
2nd: 1500 kJ·mol−1
Atomic radius 146 pm
Covalent radius 170±8 pm
Miscellanea
Crystal structure body-centered cubic
Magnetic ordering paramagnetic[1]
Electrical resistivity (20 °C) 131 nΩ·m
Thermal conductivity (300 K) 57.5 W·m−1·K−1
Thermal expansion (25 °C) 6.3 µm·m−1·K−1
Speed of sound (thin rod) (20 °C) 3400 m/s
Young's modulus 186 GPa
Shear modulus 69 GPa
Bulk modulus 200 GPa
Poisson ratio 0.34
Mohs hardness 6.5
Vickers hardness 873 MPa
Brinell hardness 800 MPa
CAS registry number 7440-25-7
Most stable isotopes
Main article: Isotopes of tantalum
iso NA half-life DM DE (MeV) DP
177Ta syn 56.56 h ε 1.166 177Hf
178Ta syn 2.36 h ε 1.910 178Hf
179Ta syn 1.82 a ε 0.110 179Hf
180Ta syn 8.125 h ε 0.854 180Hf
β− 0.708 180W
180mTa 0.012% >1.2×1015 y
(not observed) ε 0.929 180Hf
β− 0.783 180W
IT 0.075 180Ta
181Ta 99.988% 181Ta is stable with 108 neutrons
182Ta syn 114.43 d β− 1.814 182W
183Ta syn 5.1 d β− 1.070 183W
This box: view • talk • edit
Tantalum (pronounced /ˈtæntələm/, TAN-təl-əm) (formerly tantalium /tænˈtæliəm/, tan-TAL-ee-əm) is a chemical element with the symbol Ta and atomic number 73. A rare, hard, blue-gray, lustrous transition metal, tantalum is highly corrosion resistant and occurs naturally in the mineral tantalite, always together with the chemically similar niobium. It is part of the refractory metals group, which are widely used as minor component in alloys. The chemical inertness of tantalum makes it a valuable substance for laboratory equipment and a substitute for platinum, but its main use today is in tantalum capacitors in electronic equipment.
Contents [hide]
1 History
2 Characteristics
2.1 Physical
2.2 Chemical
2.3 Isotopes
2.4 Occurrence
3 Production
4 Applications
4.1 Electronics
4.2 Alloys
4.3 Other uses
5 Precautions
6 References
7 External links
[edit] History
Tantalum was discovered in Sweden in 1802 by Anders Ekeberg. One year earlier, Charles Hatchett had discovered the element columbium.[2] In 1809, the English chemist William Hyde Wollaston compared the oxides derived from both columbium—columbite, with a density 5.918 g/cm3, and tantalum—tantalite, with a density 7.935 g/cm3, and concluded that the two oxides, despite their difference in measured density, were identical. He decided to keep the name tantalum.[3] After Friedrich Wöhler confirmed these results, it was thought that columbium and tantalum were the same element. 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).[4][5] The supposed element "pelopium" was later identified as a mixture of tantalum and niobium, and it was found that the niobium was identical to the columbium already discovered in 1801 by Hattchet.
The differences between tantalum and niobium were demonstrated unequivocally in 1864 by Christian Wilhelm Blomstrand,[6] and Henri Etienne Sainte-Claire Deville, as well as by Louis J. Troost, who determined the empirical formulas of some of their compounds in 1865[6][7]. Further confirmation came from the Swiss chemist Jean Charles Galissard de Marignac,[8] in 1866, who all proved that there were only two elements. These discoveries did not stop scientists from publishing articles about the so-called ilmenium until 1871.[9] 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.[10] Early investigators had been only able to produce impure tantalum, and the first relatively pure ductile metal was produced by Werner von Bolton in 1903. Wires made with metallic tantalum were used for light bulb filaments until tungsten replaced it in widespread use.[11]
The name tantalum was derived from the name of the mythological Tantalus, the father of Niobe in Greek mythology. In the story, he had been punished after death by being condemned to stand knee-deep in water with perfect fruit growing above his head, both of which eternally tantalized him. (If he bent to drink the water, it drained below the level he could reach, and if he reached for the fruit, the branches moved out of his grasp.)[12] Ekeberg wrote "This metal I call tantalum … partly in allusion to its incapacity, when immersed in acid, to absorb any and be saturated."[13]
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. This method has been supplanted by solvent extraction from fluoride-containing solutions of tantalum.[7]
The mining of coltan, a tantalum ore, in the violently conflicted regions of the Democratic Republic of the Congo has raised ethical questions and human rights problems, and the question of endangering wildlife.[14][15][16]