Tantalum
30048
225387852
2008-07-13T12:19:36Z
JaGa
2092487
ref cleanup
{{Elementbox_header | number=73 | symbol=Ta | name=tantalum | left=[[hafnium]] | right=[[tungsten]] | above=[[niobium|Nb]] | below=[[dubnium|Db]] | color1=#ffc0c0 | color2=black }}
{{Elementbox_series | [[transition metal]]s }}
{{Elementbox_groupperiodblock | group=5 | period=6 | block=d }}
{{Elementbox_appearance_img | Ta,73| gray blue }}
{{Elementbox_atomicmass_gpm | [[1 E-25 kg|180.94788]][[List of elements by atomic mass|(2)]] }}
{{Elementbox_econfig | [[[xenon|Xe]]] 4f<sup>14</sup> 5d<sup>3</sup> 6s<sup>2</sup> }}
{{Elementbox_epershell | 2, 8, 18, 32, 11, 2 }}
{{Elementbox_section_physicalprop | color1=#ffc0c0 | color2=black }}
{{Elementbox_phase | [[solid]] }}
{{Elementbox_density_gpcm3nrt | 16.69 }}
{{Elementbox_densityliq_gpcm3mp | 15 }}
{{Elementbox_meltingpoint | k=3290 | c=3017 | f=5463 }}
{{Elementbox_boilingpoint | k=5731 | c=5458 | f=9856 }}
{{Elementbox_heatfusion_kjpmol | 36.57 }}
{{Elementbox_heatvaporiz_kjpmol | 732.8 }}
{{Elementbox_heatcapacity_jpmolkat25 | 25.36 }}
{{Elementbox_vaporpressure_katpa | 3297 | 3597 | 3957 | 4395 | 4939 | 5634 | comment= }}
{{Elementbox_section_atomicprop | color1=#ffc0c0 | color2=black }}
{{Elementbox_crystalstruct | cubic body centered }}
{{Elementbox_oxistates | '''5''', 4, 3 (mildly [[acid]]ic oxide) }}
{{Elementbox_electroneg_pauling | 1.5 }}
{{Elementbox_ionizationenergies2 | 761 | 1500 }}
{{Elementbox_atomicradius_pm | [[1 E-10 m|145]] }}
{{Elementbox_atomicradiuscalc_pm | [[1 E-10 m|200]] }}
{{Elementbox_covalentradius_pm | [[1 E-10 m|138]] }}
{{Elementbox_section_miscellaneous | color1=#ffc0c0 | color2=black }}
{{Elementbox_magnetic | no data }}
{{Elementbox_eresist_ohmmat20 | 131 n}}
{{Elementbox_thermalcond_wpmkat300k | 57.5 }}
{{Elementbox_thermalexpansion_umpmkat25 | 6.3 }}
{{Elementbox_speedofsound_rodmpsat20 | 3400 }}
{{Elementbox_youngsmodulus_gpa | 186 }}
{{Elementbox_shearmodulus_gpa | 69 }}
{{Elementbox_bulkmodulus_gpa | 200 }}
{{Elementbox_poissonratio | 0.34 }}
{{Elementbox_mohshardness | 6.5 }}
{{Elementbox_vickershardness_mpa | 873 }}
{{Elementbox_brinellhardness_mpa | 800 }}
{{Elementbox_cas_number | 7440-25-7 }}
{{Elementbox_isotopes_begin | color1=#ffc0c0 | color2=black }}
{{Elementbox_isotopes_decay | mn=177 | sym=Ta
| na=[[synthetic radioisotope|syn]] | hl=56.56 [[hour|h]]
| dm=[[electron capture|ε]] | de=1.166 | pn=177 | ps=[[hafnium|Hf]] }}
{{Elementbox_isotopes_decay | mn=178 | sym=Ta
| na=[[synthetic radioisotope|syn]] | hl=2.36 [[hour|h]]
| dm=[[electron capture|ε]] | de=1.910 | pn=178 | ps=[[hafnium|Hf]] }}
{{Elementbox_isotopes_decay | mn=179 | sym=Ta
| na=[[synthetic radioisotope|syn]] | hl=1.82 [[year|a]]
| dm=[[electron capture|ε]] | de=0.110 | pn=179 | ps=[[hafnium|Hf]] }}
{{Elementbox_isotopes_decay | mn=180 | sym=Ta
| na=[[synthetic radioisotope|syn]] | hl=8.125 [[hour|h]]
| dm=[[electron capture|ε]] | de=0.854 | pn=180 | ps=[[hafnium|Hf]] }}
{{Elementbox_isotopes_decay | mn=180 | sym=Ta
| na=[[synthetic radioisotope|syn]] | hl=8.125 [[hour|h]]
| dm=[[beta emission|β<sup>-</sup>]] | de=0.708 | pn=180 | ps=[[tungsten|W]] }}
{{Elementbox_isotopes_decay3 | mn=180[[Nuclear isomer|m]] | sym=Ta
| na=0.012% | hl=>1.2×10<sup>15</sup> [[year|y]]<br/> (not observed)
| dm1=[[electron capture|ε]] | de1=0.929 | pn1=180 | ps1=[[hafnium|Hf]]
| dm2=[[beta emission|β<sup>-</sup>]] | de2=0.783 | pn2=180 | ps2=[[tungsten|W]]
| dm3=[[Gamma ray|IT]] | de3=0.075 | pn3=180 | ps3=Ta }}
{{Elementbox_isotopes_stable | mn=181 | sym=Ta | na=99.988% | n=108 }}
{{Elementbox_isotopes_decay | mn=182 | sym=Ta
| na=[[synthetic radioisotope|syn]] | hl=114.43 [[day|d]]
| dm=[[beta emission|β<sup>-</sup>]] | de=1.814 | pn=182 | ps=[[tungsten|W]] }}
{{Elementbox_isotopes_decay | mn=183 | sym=Ta
| na=[[synthetic radioisotope|syn]] | hl=5.1 [[day|d]]
| dm=[[beta emission|β<sup>-</sup>]] | de=1.070 | pn=183 | ps=[[tungsten|W]] }}
{{Elementbox_isotopes_end}}
{{Elementbox_footer | color1=#ffc0c0 | color2=black }}
'''Tantalum''' ({{pronEng|ˈtæntələm}}) (formerly '''tantalium''' {{IPA|/tænˈtæliəm/}}) is a [[chemical element]] with the symbol '''Ta''' and [[atomic number]] 73. A rare, hard, blue-grey, [[lustre (mineralogy)|lustrous]], [[transition metal]], tantalum is highly corrosion-resistant and occurs naturally in the [[mineral]] [[tantalite]].
==Characteristics==
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 °[[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 °C (boiling point 5458 °C) is exceeded only by [[tungsten]] and [[rhenium]] for metals, and [[carbon]].
==Applications==
The major use for tantalum, as the metal powder, is in the production of electronic components, mainly capacitors and some high-power resistors<ref>[http://www.wisegeek.com/what-is-a-resistor.htm What is a resistor?]</ref>. [[tantalum capacitor|Tantalum electrolytic capacitors]] exploit the tendency of tantalum to form a protective oxide surface layer, using tantalum powder, pressed into a pellet shape, as one "plate" of the capacitor, the oxide as the dielectric, and an electrolytic solution or conductive solid 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 telephones, pagers, personal computers, and automotive electronics.
Tantalum is also used to produce a variety of alloys 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 superalloys for jet engine components, chemical process equipment, [[nuclear reactor]]s, and missile parts. Because of its ductility, tantalum can be drawn into fine wires or filaments, which are used for evaporating metals such as aluminium.
Due to the fact that it resists attack by body fluids and is nonirritating, tantalum is widely used in making surgical instruments and implants. For example, porous tantalum coatings are used in the construction of orthopedic implants due to tantalum's ability to form a direct bond to hard tissue.<ref>R. Cohen (2006). Applications of porous tantalum in total hip arthroplasty. ''Journal of the American Academy of Orthopaedic Surgeons'', 14:646-655.</ref> The oxide is used to make special high [[refractive index]] [[glass]] for [[camera]] lenses. The metal is also used to make [[vacuum furnace]] parts.
[[Shaped charge]] and [[explosively formed penetrator]] liners have been constructed from tantalum.
==History==
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 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.
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—it sits among reagents and is unaffected by them. The English word [[wiktionary:tantalize|tantalize]] was named after Tantalus, and tantalum was named after the tantalizing problems posed by the inertness of the element and its compounds.
For many years, the commercial technology for separating tantalum from niobium involved the fractional crystallization of potassium heptafluorotantalate away from potassium oxypentafluoroniobate monohydrate, that had been discovered by Marignac in the 1860s. The method has been supplanted by solvent extraction from fluoride-containing solutions.
==Occurrence==
There are many species of tantalum minerals, only some of which are so far being used by industry as raw materials: [[tantalite]], [[microlite]], [[wodginite]], [[euxenite]], [[polycrase]]. [[Tantalite]] [([[iron|Fe]],[[manganese|Mn]]) Ta<sub>2</sub>[[oxygen|O]]<sub>6</sub>] is the most important mineral for tantalum extraction.
Other minerals include [[samarskite]] and [[fergusonite]].
The main production of tantalum occurs in [[Australia]], where the largest producer, [[Talison Minerals]] (formerly part of the [[Sons of Gwalia]] company), operates the Wodgina mine.<ref name="Talison">{{Citation
| last = Talison Minerals
| first =
| author-link = Talison
| title = Wodgina Operations
| date = 2008
| year =
| url = http://www.talison.com.au/pages/wodgina.htm
| accessdate = 2008-06-03}}</ref> Tantalum minerals are also mined in [[Brazil]], [[Canada]], [[China]], [[Ethiopia]] and [[Mozambique]]. Tantalum is also produced in [[Thailand]] and [[Malaysia]] as a by-product of [[tin]] mining and smelting.
Future large sources of supply, in order of magnitude, are being explored in [[Saudi Arabia]], [[Egypt]], [[Greenland]], [[China]], [[Mozambique]], [[Canada]], [[Australia]], [[U.S.A.]], [[Finland]] and [[Brazil]].<ref name="Mining Journal">{{Citation
| last = Mining Journal
| first =
| author-link = MJ
| title = Tantalum supplement
| date = 2007-November
| year = 2007
| url = http://www.noventa.net/pdf/presentations/tanatalumSCR_presentation.pdf
| accessdate = 2008-06-03}}</ref>
A comprehensive, 2002 review of non-Australian mines is available<ref>[http://www.doir.wa.gov.au/documents/gswa/gsdMRB_22_chap10.pdf GSWA Mineral Resources Bulletin 22, Chapter 10: International tantalum resources — exploration and mining ]</ref>.
[[Tantalite]] has the same mineral structure as [[columbite]] [([[iron|Fe]],[[manganese|Mn]]) (Ta,[[niobium|Nb]])<sub>2</sub>[[oxygen|O]]<sub>6</sub>]; when there is more Ta than Nb it is called tantalite and when there is more Nb than Ta is it called columbite (or [[niobite]]). In [[central Africa]] the colloquial term [[coltan]] is used to refer to the two minerals equally, an example being the [[Democratic Republic of the Congo]] which the [[United States Geological Survey]] reports in its 2006 yearbook as having produced a little less than 1% of the world's tantalum for the past four years.<ref name="USGS">{{Citation
| last = US Geological Survey
| first =
| author-link = USGS
| title = 2006 Minerals Yearbook Nb & Ta
| date = 2006
| year =
| url = http://minerals.usgs.gov/minerals/pubs/commodity/niobium/#pubs
| accessdate = 2008-06-03}}</ref>
Ethical questions have been raised about responsible corporate behaviour, human rights and endangered wildlife, due to the exploitation of resources such as coltan in the conflict regions of the Congo. According to [[United Nations]] report<ref>
{{Citation
| first = Panel of Experts on the Illegal Exploitation of Natural Resources and Other Forms of Wealth in the Democratic Republic of the Congo
| author-link =
| title = S/2003/1027
| date = 2003-10-26
| year = 2003
| url = http://www.un.org/Docs/journal/asp/ws.asp?m=S/2003/1027
| accessdate =2008-04-19 }}</ref> smuggling and exportation of coltan helped fuel the war in the Congo, a crisis that has resulted in approximately 5.4 million<ref>{{Citation
| last = International Rescue Committee
| author-link =
| title = Special Report: Congo
| date =
| year =
| url = http://www.theirc.org/special-report/congo-forgotten-crisis.html
| accessdate = 2008-04-19}}
</ref> deaths since 1998 – making it the world’s deadliest documented conflict since [[WW_II|WW II]].
Several complicated steps are involved in the extraction of tantalum from tantalite, the first being [[crusher|crushing]] of the mineral and physical concentration by [[gravity separation]] which is generally carried out near the [[mining|mine]] site. Further processing by [[chemical process|chemical separation]] is generally accomplished by treating the ores with a mixture of [[hydrofluoric acid]] and [[sulfuric acid]]s at over 90°C. This causes the tantalum and niobium to dissolve as [[complex (chemistry)|complex]] [[fluoride]]s and be separated from the [[impurities]]. The resulting [[potassium]] fluorotantalate [[salt (chemistry)|salt]] is generally treated by [[reduction]] with molten [[sodium]] to produce a coarse tantalum powder.<ref>
{{Citation
| last = T.I.C.
| author-link =
| title = Extraction/refining
| date =
| year =
| url = http://www.tanb.org/tantalum1.html
| accessdate =2008-06-03}}</ref>
==Compounds==
{{Expand|date=January 2008}}
[[Los Alamos National Laboratory]] scientists have developed a [[tantalum carbide]]-[[graphite]] [[alloy|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.<ref>[http://english.chosun.com/w21data/html/news/200505/200505060005.html Digital Chosunilbo (English Edition) : Daily News in English About Korea<!-- Bot generated title -->]</ref>
''See also [[:Category:Tantalum compounds|tantalum compounds]].''
==Isotopes==
{{main|isotopes of tantalum}}
Natural tantalum consists of two [[isotope]]s: <sup>180m</sup>Ta (0.012%) and <sup>181</sup>Ta (99.988%). <sup>181</sup>Ta is a [[stable isotope]]. <sup>180m</sup>Ta (''m'' denotes a metastable state) is predicted to decay in three ways: [[isomeric transition]] to the [[ground state]] of <sup>180</sup>Ta, [[beta decay]] to <sup>180</sup>[[Tungsten|W]], electron capture to <sup>180</sup>[[Hafnium|Hf]]. However, any radioactivity of this [[nuclear isomer]] was never observed. Only a lower limit on its [[half life]] of over [[1 E15|10<sup>15</sup>]] years has been set. The ground state of <sup>180</sup>Ta has a half life of only 8 hours.
<sup>180m</sup>Ta is the only naturally occurring [[nuclear isomer]] (excluding radiogenic and cosmogenic short-living nuclides). It is also the rarest isotope in the Universe, taking into account the elemental abundance of tantalum and isotopic abundance of <sup>180m</sup>Ta in the natural mixture of isotopes.
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.
== Precautions ==
Compounds containing tantalum are rarely encountered in the laboratory. The metal is highly [[biocompatible]] and is used for body [[implant (medicine)|implant]]s and [[coating]]s, therefore attention may be focused on other elements or the physical nature of the [[chemical compound]].<ref>
{{Citation
| last = Biomaterials
| author-link =
| title = Biocompatibility of tantalum
| date = 2001
| year =
| url = http://www.ncbi.nlm.nih.gov/pubmed/11336297
| accessdate =2008-06-03}}</ref>
The only concern in the laboratory with tantalum is with the powder form: as is common with finely divided metal powders this may catch [[fire]].
A single study from 1956 (Oppenheimer, B.S., Oppenheimer, E.T., Danishefsky, I. & Stout, A.P.
(1956) Carcinogenic effects of metals in rodent. Cancer Res., 16, 439-441) is the only reference in literature ever linking tantalum to local [[sarcoma]]s. It is possible the result was due to other factors not considered in the study. The study was quoted in [[International Agency for Research on Cancer|IARC]] Monograph vol. 74 which includes the following "Note to the reader": "Inclusion of an agent in the Monographs does not imply that it is a [[carcinogen]], only that the published data have been examined."<ref>
{{Citation
| last = IARC
| author-link =
| title = Surgical implants and other foreign bodies
| date = 1999
| year = 1999
| url = http://www.inchem.org/documents/iarc/vol74/implants.html
| accessdate =2008-06-03}}</ref>
==References==
{{reflist|2}}
==External links==
{{wiktionary|tantalum}}
{{Commons|Tantalum}}
*[http://www.webelements.com/webelements/elements/text/Ta/index.html WebElements.com - Tantalum]
*[http://www.tanb.org/ Tantalum-Niobium International Study Center]
*[http://periodic.lanl.gov/elements/73.html Los Alamos National Laboratory - Tantalum]
*[http://www.tanb.org/tantalum1.html T.I.C. industry site] - Tantalum uses, ore mining and extraction
{{clear}}
{{Compact periodic table}}
[[Category:Chemical elements]]
[[Category:Transition metals]]
[[Category:Tantalum|*]]
<!-- interwiki -->
[[af:Tantaal]]
[[ar:تانتالوم]]
[[az:Tantal]]
[[bn:ট্যানটালাম]]
[[be:Тантал]]
[[bs:Tantal]]
[[bg:Тантал (химичен елемент)]]
[[ca:Tàntal]]
[[cs:Tantal]]
[[co:Tantaliu]]
[[da:Tantal]]
[[de:Tantal]]
[[et:Tantaal]]
[[el:Ταντάλιο]]
[[es:Tantalio]]
[[eo:Tantalo]]
[[eu:Tantalo]]
[[fa:تانتالیوم]]
[[fr:Tantale (chimie)]]
[[fur:Tantali]]
[[gv:Tantalum]]
[[gl:Tantalio]]
[[ko:탄탈럼]]
[[hy:Տանտալ]]
[[hr:Tantal (element)]]
[[io:Tantalo]]
[[id:Tantalum]]
[[is:Tantal]]
[[it:Tantalio]]
[[he:טנטלום]]
[[jv:Tantalum]]
[[sw:Tantali]]
[[ht:Tantal]]
[[ku:Tantal]]
[[la:Tantalum]]
[[lv:Tantāls]]
[[lb:Tantal]]
[[lt:Tantalas]]
[[jbo:jinmrtantalu]]
[[hu:Tantál]]
[[ml:ടാന്റാലം]]
[[nah:Nelnextictepoztli]]
[[nl:Tantalium]]
[[ja:タンタル]]
[[no:Tantal]]
[[nn:Tantal]]
[[oc:Tantal (quimia)]]
[[pl:Tantal (pierwiastek)]]
[[pt:Tântalo (elemento químico)]]
[[ro:Tantal (chimie)]]
[[ru:Тантал (элемент)]]
[[sq:Tantali]]
[[scn:Tantaliu]]
[[simple:Tantalum]]
[[sk:Tantal]]
[[sl:Tantal (element)]]
[[sr:Тантал]]
[[sh:Tantalijum]]
[[fi:Tantaali]]
[[sv:Tantal]]
[[th:แทนทาลัม]]
[[vi:Tantali]]
[[tr:Tantal]]
[[uk:Тантал (хімічний елемент)]]
[[zh:钽]]