Difference between revisions of "Tantalum" - New World Encyclopedia

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'''Tantalum''', formerly '''tantalium''' (chemical symbol '''Ta''', [[atomic number]] 73) is a rare, hard, blue-gray, lustrous, [[transition metal]]. It is highly corrosion-resistant and occurs in the [[mineral]] [[tantalite]]*.
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'''Tantalum''', formerly '''tantalium''' (chemical symbol '''Ta''', [[atomic number]] 73) is a rare, blue-gray, lustrous [[metal]]. It is very hard, has a high [[melting point]], and is highly resistant to [[corrosion]]. It occurs in the [[mineral]] [[tantalite]]*.
  
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== Occurrence ==   
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== Occurrence and isolation ==   
  
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Tantalum occurs principally in the minerals [[tantalite]]* [([[iron|Fe]], [[manganese|Mn]]) Ta<sub>2</sub>[[oxygen|O]]<sub>6</sub>] and [[euxenite]]* (other minerals: [[samarskite]]* and [[fergusonite]]*).
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Tantalum occurs principally in the minerals [[tantalite]]* [([[iron|Fe]], [[manganese|Mn]]) Ta<sub>2</sub>[[oxygen|O]]<sub>6</sub>] and [[euxenite]]* [(Y,Ca,Ce,U,Th)(Nb,Ta,Ti)<sub>2</sub>O<sub>6</sub>]. Tantalite is usually found mixed with [[columbite]]* in an ore called [[coltan]]*. Other minerals containing tantalum include [[samarskite]]* and [[fergusonite]]*.
  
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Tantalum [[ore]]s are mined in [[Ethiopia]], [[Australia]], [[Brazil]], [[Egypt]], [[Canada]], the [[Democratic Republic of the Congo]], [[Mozambique]], [[Nigeria]], [[Portugal]], [[Malaysia]] and [[Thailand]]. A comprehensive, 2002 [http://www.doir.wa.gov.au/documents/gswa/gsdMRB_22_chap10.pdf picture] of non-Australian mines is reasonably current.
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Tantalum [[ore]]s are mined in [[Ethiopia]], [[Australia]], [[Brazil]], [[Egypt]], [[Canada]], the [[Democratic Republic of the Congo]], [[Mozambique]], [[Nigeria]], [[Portugal]], [[Malaysia]], and [[Thailand]].<ref>[http://www.doir.wa.gov.au/documents/gswa/gsdMRB_22_chap10.pdf International tantalum resources] - a comprehensive picture, as of 2002</ref> The exploitation of resources in the conflict regions of the Congo has raised ethical questions about human rights and endangered wildlife.
  
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Tantalite is largely found mixed with [[columbite]]* in an ore called [[coltan]]*. Ethical questions have been raised about human rights and endangered wildlife, due to the exploitation of resources in the conflict regions of the Congo.
+
Several complicated steps are involved in the separation of tantalum from [[niobium]]. Commercially viable production of this element can follow one of several different methods, such as: (a) [[electrolysis]] of molten [[potassium]] fluorotantalate; (b) [[redox|reduction]] of potassium fluorotantalate with [[sodium]]; or (c) reacting tantalum carbide with tantalum oxide. Tantalum is also a byproduct from [[tin]] smelting.
  
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Several complicated steps are involved in the separation of tantalum from [[niobium]]. Commercially viable production of this element can follow one of several different methods which includes; [[electrolysis]] of molten [[potassium]] fluorotantalate, [[redox|reduction]] of potassium fluorotantalate with [[sodium]], or by reacting tantalum carbide with tantalum oxide. Tantalum is also a byproduct from [[tin]] smelting.
+
== History and etymology ==
  
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== History ==
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Tantalum was discovered in [[Sweden]] in 1802 by [[Anders Ekeberg]]* and isolated in 1820 by [[Jöns Berzelius]]*. Many contemporary chemists believed [[niobium]] and tantalum were the same element, until researchers showed (in 1844 and 1866) that niobic and tantalic acids are different compounds. Early investigators were able to isolate just the impure metal, and the first relatively pure, ductile metal was produced by [[Werner von Bolton]]* in 1903. Wires made with tantalum metal were used for [[light bulb]]s until it was replaced by [[tungsten]].
  
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Tantalum ([[Greek language|Greek]] ''Tantalus'', mythological character) was discovered in [[Sweden]] in 1802 by [[Anders Ekeberg]]* and isolated in 1820 by [[Jöns Berzelius]]. Many contemporary chemists believed [[niobium]] and tantalum were the same elements until 1844 and later 1866, when researchers showed that niobic and tantalic acids were different compounds. Early investigators were only able to isolate impure metal and the first relatively pure ductile metal was produced by [[Werner von Bolton]]* in 1903. Wires made with tantalum metal were used for [[light bulb]]s until [[tungsten]] replaced it.
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The name tantalum is derived from the [[Greek]] mythological character [[Tantalos]]*, father of [[Niobe]]*. Tantalus was 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. This was considered similar to tantalum's general non-reactivity&mdash;it is unaffected by reagents and is therefore difficult to refine.
  
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Its name is derived from the character [[Tantalus]]*, father of [[Niobe]]* in [[Greek mythology]], who was 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. This was considered similar to tantalum's general non-reactivity&mdash;it sits among reagents and is unaffected by them. Tantalum was named after the Greek myth due to being difficult to refine.
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== Notable characteristics ==
  
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== Notable characteristics ==
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Tantalum is a [[transition metal]] that lies in period 6 of the [[periodic table]], between [[hafnium]] and [[tungsten]]. In addition, it is located in group 5 (former group 5B), just below [[niobium]], and its chemical properties are similar to those of niobium.
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Tantalum is  dark,  dense, ductile, very hard, easily fabricated, and highly conductive of heat and electricity. The metal is renowned for its resistance to [[corrosion]] by [[acid]]s; in fact, at temperatures below 150&nbsp;°[[Celsius|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 [[sulfur trioxide]], as well as with a solution of [[potassium hydroxide]]. Tantalum's high melting point of 3017&nbsp;°C (boiling point 5458&nbsp;°C) is exceeded only by [[tungsten]] and [[rhenium]].
+
 
 +
This element is  dark,  dense, ductile, very hard, and easily fabricated. It is highly conductive of heat and electricity. It is renowned for its resistance to [[corrosion]] by [[acid]]s. At temperatures below 150&nbsp;°C, it 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 [[sulfur trioxide]], as well as with a solution of [[potassium hydroxide]]. Tantalum's melting point of 3,017&nbsp;°C (boiling point 5,458&nbsp;°C) is exceeded only by the melting points of [[tungsten]] and [[rhenium]].
  
 
=== Isotopes ===
 
=== Isotopes ===
  
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Natural tantalum consists of two [[isotope]]s. Ta-181 is a stable isotope, and Ta-180m has a [[half life]] of over [[1 E15|10<sup>15</sup>]] years (see [[scientific notation]]) and is a [[nuclear isomer]] of Ta-180. Ta-180 has a [[ground state]]  [[half life]] of only 8 hours.
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Natural tantalum consists of two [[isotope]]s: Ta-181 is a stable isotope, and Ta-180m has a [[half life]] of over [[1 E15|10<sup>15</sup>]] years (see [[scientific notation]]). In addition, numerous radioactive isotopes (atomic mass numbers ranging from 155 to 190) have been produced artificially, with very short half-lives.
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Tantalum has been proposed as a "[[Salted bomb|salting]]" material for [[nuclear weapon]]s ([[cobalt]] is another, better-known salting material). A jacket of <sup>181</sup>Ta, irradiated by the intense high-energy neutron flux from an exploding thermonuclear weapon, would transmute into the radioactive isotope <sup>182</sup>Ta with a [[half-life]] of 114.43 days and produce approximately 1.12 [[MeV]] of [[Gamma ray|gamma radiation]], significantly increasing the radioactivity of the weapon's [[Nuclear fallout|fallout]] for several months. Such a weapon is not known to have ever been built, tested, or used.
 
  
 
== Compounds ==  
 
== Compounds ==  
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== Applications ==  
 
== Applications ==  
  
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The major use for tantalum, as the metal powder, is in the production of electronic components, mainly [[capacitor]]s and some high-end audio grade [[resistor]]s. Tantalum [[electrolytic capacitor]]s exploit the tendency of tantalum to form a protective oxide surface layer, using tantalum foil as one plate of the capacitor, the oxide as the [[dielectric]], and an electrolytic solution as the other plate. Because the dielectric layer can be very thin (thinner than the similar layer in, for instance, an [[aluminium]] [[electrolytic capacitor]]), a high [[capacitance]] can be achieved in a small volume. Because of the size and weight advantages, tantalum capacitors are attractive for portable [[telephone]]s, [[pager]]s, [[personal computer]]s, and automotive electronics.  
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The major use for tantalum, as the metal powder, is in the production of electronic components, mainly [[capacitor]]s and some high-end, audio-grade [[resistor]]s. Tantalum [[electrolytic capacitor]]*s exploit the tendency of tantalum to form a protective oxide surface layer, using tantalum foil as one plate of the capacitor, the oxide as the [[dielectric]]* (electrical insulator between plates), and an electrolytic solution as the other plate. Because the dielectric layer can be very thin (thinner than the similar layer in, for instance, an [[aluminum]] [[electrolytic capacitor]]*), high [[capacitance]] can be achieved in a small volume. Given the size and weight advantages, tantalum capacitors are attractive for portable [[telephone]]s, [[pager]]s, [[personal computer]]s, and automotive electronics.  
  
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Tantalum is also used to produce a variety of [[alloy]]s that have high melting points, are strong and have good ductility. Alloyed with other metals, it is also used in making carbide tools for metalworking equipment and in the production of [[superalloy]]s for [[jet engine]] components, chemical process equipment, [[nuclear reactor]]s, and [[missile]] parts. Because of its ductility, Ta can be drawn into fine wires or filaments, which are used for evaporating metals such as [[aluminium]].
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Tantalum is also used to produce a variety of strong, ductile [[alloy]]s that have high melting points. Alloyed with other metals, it is also used in making carbide tools for metalworking equipment and in the production of [[superalloy]]s for [[jet engine]] components, chemical process equipment, [[nuclear reactor]]s, and [[missile]] parts. Tantalum wires and filaments are used for evaporating metals such as [[aluminum]].
  
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Due to the fact that it resists attack by body fluids and is nonirritating, tantalum is widely used in making surgical instruments and implants. The oxide is used to make special high [[refractive index]] [[glass]] for [[camera]] lenses. The metal is also used to make [[vacuum furnace]] parts.
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Given that tantalum resists attack by body fluids and is nonirritating, it is widely used in making surgical instruments and implants. The oxide is used to make special [[glass]] (with high [[refractive index]]) for [[camera]] lenses. The metal is also used to make parts for [[vacuum furnace]]*s.
  
 
== Precautions ==  
 
== Precautions ==  
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Compounds containing tantalum are rarely encountered, and the metal does not normally cause problems in the laboratory, but it should still be handled with care, taking the usual laboratory precautions. There is some evidence that tantalum compounds can cause [[tumor]]s, and its metal dust is a [[fire]] and [[explosion]] hazard.
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 +
Compounds containing tantalum are rarely encountered, and the metal does not normally cause problems in the laboratory. Nonetheless, it should be handled with care, taking the usual laboratory precautions. There is some evidence that tantalum compounds can cause [[tumor]]s, and its metal dust is a [[fire]] and [[explosion]] hazard.
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==Footnotes==
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<references />
  
 
== References ==
 
== References ==
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*[http://periodic.lanl.gov/elements/73.html Los Alamos National Laboratory - Tantalum]
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*[http://www.tanb.org/tantalum1.html T.I.C. industry site] - Tantalum uses, ore mining and extraction
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* Fairbrother, F., ''The Chemistry of Niobium and Tantalum'', New York: Elsevier Publishing Company (1967). ASIN B0006BQA7U
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* Cotton, F. Albert; and Wilkinson, Geoffrey (1980), ''Advanced Inorganic Chemistry'' (4th ed.), New York: Wiley. ISBN 0-471-02775-8.
 +
*[http://periodic.lanl.gov/elements/73.html Tantalum] Los Alamos National Laboratory. Accessed on November 28, 2006.
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*[http://www.tanb.org/tantalum1.html Tantalum - raw materials and processing] T.I.C. industry site. Accessed on November 28, 2006.
 +
* [http://www.speclab.com/elements/tantalum.htm Tantalum] SPECTRUM Chemical Fact Sheet. Accessed on November 28, 2006.
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*[http://www.webelements.com/webelements/elements/text/Ta/index.html Tantalum] WebElements.com. Accessed on November 28, 2006.
  
 
== External links ==
 
== External links ==
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*[http://www.webelements.com/webelements/elements/text/Ta/index.html WebElements.com - Tantalum]
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*[http://www.tanb.org/ Tantalum-Niobium International Study Center]
 
*[http://www.tanb.org/ Tantalum-Niobium International Study Center]
  
 
[[Category:Physical sciences]]
 
[[Category:Physical sciences]]
 
[[Category:Chemistry]]
 
[[Category:Chemistry]]
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[[Category:Earth sciences]]
  
 
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{{credit|88829554}}

Revision as of 15:58, 28 November 2006

73 hafnium ← tantalum → tungsten
Nb
↑
Ta
↓
Db
Ta-TableImage.png
periodic table
General
Name, Symbol, Number tantalum, Ta, 73
Chemical series transition metals
Group, Period, Block 5, 6, d
Appearance gray blue
Ta,73.jpg
Atomic mass 180.94788(2) g/mol
Electron configuration [Xe] 4f14 5d3 6s2
Electrons per shell 2, 8, 18, 32, 11, 2
Physical properties
Phase solid
Density (near r.t.) 16.69 g/cm³
Liquid density at m.p. 15 g/cm³
Melting point 3290 K
(3017 °C, 5463 °F)
Boiling point 5731 K
(5458 °C, 9856 °F)
Heat of fusion 36.57 kJ/mol
Heat of vaporization 732.8 kJ/mol
Heat capacity (25 °C) 25.36 J/(mol·K)
Vapor pressure
P/Pa 1 10 100 1 k 10 k 100 k
at T/K 3297 3597 3957 4395 4939 5634
Atomic properties
Crystal structure cubic body centered
Oxidation states 5 (mildly acidic oxide)
Electronegativity 1.5 (Pauling scale)
Ionization energies 1st: 761 kJ/mol
2nd: 1500 kJ/mol
Atomic radius 145 pm
Atomic radius (calc.) 200 pm
Covalent radius 138 pm
Miscellaneous
Magnetic ordering no data
Electrical resistivity (20 °C) 131 nΩ·m
Thermal conductivity (300 K) 57.5 W/(m·K)
Thermal expansion (25 °C) 6.3 µm/(m·K)
Speed of sound (thin rod) (20 °C) 3400 m/s
Speed of sound (thin rod) (r.t.) 186 m/s
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
Notable isotopes
Main article: [[Isotopes of {{{isotopesof}}}]]
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
180Ta syn 8.125 h β- 0.708 180W
180mTa 0.012% >1.2×1015 y ε 0.929 180Hf
β- 0.783 180W
IT 0.075 180Ta
181Ta 99.988% Ta is stable with 108 neutrons
182Ta syn 114.43 d β- 1.814 182W
183Ta syn 5.1 d β- 1.070 183W

Tantalum, formerly tantalium (chemical symbol Ta, atomic number 73) is a rare, blue-gray, lustrous metal. It is very hard, has a high melting point, and is highly resistant to corrosion. It occurs in the mineral tantalite.

Occurrence and isolation

Tantalum occurs principally in the minerals tantalite [(Fe, Mn) Ta2O6] and euxenite [(Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6]. Tantalite is usually found mixed with columbite in an ore called coltan. Other minerals containing tantalum include samarskite and fergusonite.

Tantalum ores are mined in Ethiopia, Australia, Brazil, Egypt, Canada, the Democratic Republic of the Congo, Mozambique, Nigeria, Portugal, Malaysia, and Thailand.[1] The exploitation of resources in the conflict regions of the Congo has raised ethical questions about human rights and endangered wildlife.

Several complicated steps are involved in the separation of tantalum from niobium. Commercially viable production of this element can follow one of several different methods, such as: (a) electrolysis of molten potassium fluorotantalate; (b) reduction of potassium fluorotantalate with sodium; or (c) reacting tantalum carbide with tantalum oxide. Tantalum is also a byproduct from tin smelting.

History and etymology

Tantalum was discovered in Sweden in 1802 by Anders Ekeberg and isolated in 1820 by Jöns Berzelius. Many contemporary chemists believed niobium and tantalum were the same element, until researchers showed (in 1844 and 1866) that niobic and tantalic acids are different compounds. Early investigators were able to isolate just the impure metal, and the first relatively pure, ductile metal was produced by Werner von Bolton in 1903. Wires made with tantalum metal were used for light bulbs until it was replaced by tungsten.

The name tantalum is derived from the Greek mythological character Tantalos, father of Niobe. Tantalus was 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. This was considered similar to tantalum's general non-reactivity—it is unaffected by reagents and is therefore difficult to refine.

Notable characteristics

Tantalum is a transition metal that lies in period 6 of the periodic table, between hafnium and tungsten. In addition, it is located in group 5 (former group 5B), just below niobium, and its chemical properties are similar to those of niobium.

This element is dark, dense, ductile, very hard, and easily fabricated. It is highly conductive of heat and electricity. It is renowned for its resistance to corrosion by acids. At temperatures below 150 °C, it 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 sulfur trioxide, as well as with a solution of potassium hydroxide. Tantalum's melting point of 3,017 °C (boiling point 5,458 °C) is exceeded only by the melting points of tungsten and rhenium.

Isotopes

Natural tantalum consists of two isotopes: Ta-181 is a stable isotope, and Ta-180m has a half life of over 1015 years (see scientific notation). In addition, numerous radioactive isotopes (atomic mass numbers ranging from 155 to 190) have been produced artificially, with very short half-lives.

Compounds

Los Alamos National Laboratory scientists have developed a tantalum carbide-graphite composite material that is one of the hardest materials ever synthesized. Korean researchers have developed an amorphous tantalum-tungsten-copper alloy which is more flexible and two to three times stronger than traditional steel alloys.

See also tantalum compounds.

Applications

The major use for tantalum, as the metal powder, is in the production of electronic components, mainly capacitors and some high-end, audio-grade resistors. Tantalum electrolytic capacitors exploit the tendency of tantalum to form a protective oxide surface layer, using tantalum foil as one plate of the capacitor, the oxide as the dielectric (electrical insulator between plates), and an electrolytic solution as the other plate. Because the dielectric layer can be very thin (thinner than the similar layer in, for instance, an aluminum electrolytic capacitor), high capacitance can be achieved in a small volume. Given the size and weight advantages, tantalum capacitors are attractive for portable telephones, pagers, personal computers, and automotive electronics.

Tantalum is also used to produce a variety of strong, ductile alloys that have high melting points. 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, and missile parts. Tantalum wires and filaments are used for evaporating metals such as aluminum.

Given that tantalum resists attack by body fluids and is nonirritating, it is widely used in making surgical instruments and implants. The oxide is used to make special glass (with high refractive index) for camera lenses. The metal is also used to make parts for vacuum furnaces.

Precautions

Compounds containing tantalum are rarely encountered, and the metal does not normally cause problems in the laboratory. Nonetheless, it should be handled with care, taking the usual laboratory precautions. There is some evidence that tantalum compounds can cause tumors, and its metal dust is a fire and explosion hazard.

Footnotes

  1. ↑ International tantalum resources - a comprehensive picture, as of 2002

References
ISBN links support NWE through referral fees

  • Fairbrother, F., The Chemistry of Niobium and Tantalum, New York: Elsevier Publishing Company (1967). ASIN B0006BQA7U
  • Cotton, F. Albert; and Wilkinson, Geoffrey (1980), Advanced Inorganic Chemistry (4th ed.), New York: Wiley. ISBN 0-471-02775-8.
  • Tantalum Los Alamos National Laboratory. Accessed on November 28, 2006.
  • Tantalum - raw materials and processing T.I.C. industry site. Accessed on November 28, 2006.
  • Tantalum SPECTRUM Chemical Fact Sheet. Accessed on November 28, 2006.
  • Tantalum WebElements.com. Accessed on November 28, 2006.

External links

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