Editing Group 5 element

{{good article}}
{{Short description|Group of elements in the periodic table}}
{{Use dmy dates|date=March 2023}}
{{Infobox periodic table group
| title       = Group&nbsp;5 {{nowrap|in the periodic table}}
| group number= 5
| trivial name=
| by element  = vanadium group
| CAS         = VB
| old IUPAC   = VA
| mark        = V,Nb,Ta,Db
| left        = [[Group 4 element|group 4]]
| right       = [[Group 6 element|group 6]]
}}
{| class="floatright"
! colspan=2 style="text-align:left;" | ↓&nbsp;<small>[[Period (periodic table)|Period]]</small>
|-
| [[Period 4 element|4]]
| {{element cell image|23|Vanadium|V| |Solid|Transition metal|Primordial|image=Vanadium_crystal_bar_and_1cm3_cube.jpg|image caption=Vanadium etched}}
|-
! [[Period 5 element|5]]
| {{element cell image|41|Niobium|Nb| |Solid|Transition metal|Primordial|image=Niobium crystals and 1cm3 cube.jpg|image caption=Niobium crystals}}
|-
! [[Period 6 element|6]]
| {{element cell image|73|Tantalum|Ta| |Solid|Transition metal|Primordial|image=Tantalum single crystal and 1cm3 cube.jpg|image caption=Tantalum, a single crystal}}
|-
! [[Period 7 element|7]]
| {{element cell image|105|Dubnium|Db| |Unknown phase|Transition metal|Synthetic}}
|-
| colspan="2"|
----
''Legend''
{| style="text-align:center; border:0; margin:1em auto;"
|-
| style="border:{{element color|Primordial}}; background:{{Element color|table mark}}; padding:0 2px;" | [[primordial element]]
|-
| style="border:{{element color|Synthetic}}; background:{{Element color|table mark}}; padding:0 2px;" | [[synthetic element]]
|}
|}

'''Group 5''' is a [[Group (periodic table)|group of elements]] in the [[periodic table]]. Group 5 contains [[vanadium]] (V), [[niobium]] (Nb), [[tantalum]] (Ta) and [[dubnium]] (Db).<ref>{{cite book |last1=Reich |first1=Herb |title=Numberpedia: Everything You Ever Wanted to Know (and a Few Things You Didn't) About Numbers |date=2011 |publisher=Skyhorse Publishing |location=New York |isbn=978-1616080846 |pages=512}}</ref> This group lies in the [[d-block]] of the periodic table. This group is sometimes called the '''vanadium group''' or '''vanadium family''' after its lightest member; however, the group itself has not acquired a [[trivial name]] because it belongs to the broader grouping of the [[transition metal]]s.

As is typical for early transition metals, niobium and tantalum have only the group [[oxidation state]] of +5 as a major one, and are quite electropositive (it is easy to donate electrons) and have a less rich coordination chemistry (the chemistry of metallic ions bound with molecules). Due to the effects of the [[lanthanide contraction]], the decrease in ionic radii in the [[lanthanide]]s, they are very similar in properties. Vanadium is somewhat distinct due to its smaller size: it has well-defined +2, +3 and +4 states as well (although +5 is more stable).

The lighter three Group 5 elements occur naturally and share similar properties; all three are hard [[refractory metals]] under standard conditions. The fourth element, [[dubnium]], has been synthesized in laboratories, but it has not been found occurring in nature, with half-life of the most stable isotope, dubnium-268, being only 16 hours, and other isotopes even more [[radioactive]].

== History ==

[[File:'Andrés Manuel de Río' (1825) by Rafael Ximeno y Planes - Museo Tolsá - Palacio de Minería - Mexico 2024.jpg|thumb|right|Andrés Manuel del Río, the discoverer of vanadium]]

''Group 5'' is the new IUPAC name for this group; the old style name was ''group VB'' in the old US system (CAS) or ''group VA'' in the European system (old IUPAC). Group 5 must not be confused with the group with the old-style group crossed names of either ''VA'' (US system, CAS) or ''VB'' (European system, old IUPAC); that group is now called the [[pnictogen]]s or group 15.<ref name="Fluck 1988">{{cite journal |last1=Fluck |first1=E. |year=1988 |title=New Notations in the Periodic Table |url=http://www.iupac.org/publications/pac/1988/pdf/6003x0431.pdf |journal=[[Pure and Applied Chemistry|Pure Appl. Chem.]] |publisher=[[International Union of Pure and Applied Chemistry|IUPAC]] |volume=60 |issue=3 |pages=431–436 |doi=10.1351/pac198860030431 |s2cid=96704008 |access-date=24 March 2012}}</ref>

=== Vanadium ===

Vanadium was [[discovery of the chemical elements|discovered]] in 1801 by the Spanish mineralogist [[Andrés Manuel del Río]]. Del Río extracted the element from a sample of Mexican "brown lead" ore, later named [[vanadinite]]. He found that its salts exhibit a wide variety of colors, and as a result he named the element ''panchromium'' (Greek: παγχρώμιο "all colors"). Later, Del Río renamed the element ''erythronium'' (Greek: ερυθρός "red") because most of the salts turned red upon heating. In 1805, French chemist [[Hippolyte Victor Collet-Descotils]], backed by del Río's friend Baron [[Alexander von Humboldt]], incorrectly declared that del Río's new element was an impure sample of [[chromium]]. Del Río accepted Collet-Descotils' statement and retracted his claim.<ref name="Cintas">{{cite journal|title= The Road to Chemical Names and Eponyms: Discovery, Priority, and Credit|author= Cintas, Pedro|journal= Angewandte Chemie International Edition|volume= 43|issue= 44|date= 2004|pmid= 15376297|doi= 10.1002/anie.200330074|pages= 5888–94}}</ref>

In 1831 Swedish chemist [[Nils Gabriel Sefström]] rediscovered the element in a new oxide he found while working with [[iron ore]]s. Later that year, [[Friedrich Wöhler]] confirmed del Río's earlier work.<ref name="sefs">{{cite journal|title= Ueber das Vanadin, ein neues Metall, gefunden im Stangeneisen von Eckersholm, einer Eisenhütte, die ihr Erz von Taberg in Småland bezieht|first= N. G.|last= Sefström|journal= [[Annalen der Physik und Chemie]]|volume= 97|issue= 1|pages= 43–49|date= 1831|doi= 10.1002/andp.18310970103|bibcode= 1831AnP....97...43S|url= https://zenodo.org/record/1423544}}</ref> Sefström chose a name beginning with V, which had not yet been assigned to any element. He called the element ''vanadium'' after [[Old Norse]] ''[[list of names of Freyja|Vanadís]]'' (another name for the [[Norse mythology|Norse]] [[Vanir]] goddess [[Freyja]], whose attributes include beauty and fertility), because of the many beautifully colored [[chemical compound]]s it produces.<ref name="sefs" /> In 1831, the geologist [[George William Featherstonhaugh]] suggested that vanadium should be renamed ''rionium'' after del Río, but this suggestion was not followed.<ref>{{cite journal |journal= The Monthly American Journal of Geology and Natural Science |first= George William|last= Featherstonhaugh |title=New Metal, provisionally called Vanadium |year= 1831|page=69 |url= https://archive.org/stream/monthlyamericanj11831phil#page/68/mode/2up/search/rionium}}</ref><!--Featherstonhaugh, the editor of the journal cited, comments on a letter from Berzelious to [[Pierre Louis Dulong]]-->

=== Niobium and tantalum ===

[[File:Charles Hatchett. Soft-ground etching by F. C. Lewis after T Wellcome V0002614 (cropped).jpg|thumb|right|Charles Hatchett, the discover of niobium]]

Niobium was [[Discovery of the chemical elements|identified]] by English chemist [[Charles Hatchett]] in 1801.<ref name="Hatchett_1802a">{{cite journal|last=Hatchett|first=Charles|author-link=Charles Hatchett|year=1802|url=https://books.google.com/books?id=c-Q_AAAAYAAJ&pg=PA49|title=An analysis of a mineral substance from North America, containing a metal hitherto unknown|journal=Philosophical Transactions of the Royal Society of London|volume=92|pages=49–66|jstor=107114|doi=10.1098/rspl.1800.0045|doi-access=free|access-date=15 July 2016|archive-date=3 May 2016|archive-url=https://web.archive.org/web/20160503233004/https://books.google.com/books?id=c-Q_AAAAYAAJ&pg=PA49|url-status=live|url-access=subscription}}</ref><ref name="Hatchett_1802b">{{Citation |last=Hatchett |first=Charles |author-link=Charles Hatchett |year=1802 |title=Outline of the Properties and Habitudes of the Metallic Substance, lately discovered by Charles Hatchett, Esq. and by him denominated Columbium |journal=[[Journal of Natural Philosophy, Chemistry, and the Arts]] |volume=I (January) |pages=32–34 |url=https://books.google.com/books?id=ylZwOmyBA7IC&pg=PA32 |postscript=. |access-date=13 July 2017 |archive-date=24 December 2019 |archive-url=https://web.archive.org/web/20191224164852/https://books.google.com/books?id=ylZwOmyBA7IC&pg=PA32 |url-status=live }}</ref><ref name="Hatchett_1802c">{{cite journal |last=Hatchett |first=Charles |author-link=Charles Hatchett |year=1802 |title=Eigenschaften und chemisches Verhalten des von Charles Hatchett entdeckten neuen Metalls, Columbium |trans-title=Properties and chemical behavior of the new metal, columbium, (that was) discovered by Charles Hatchett |language=de |journal=[[Annalen der Physik]] |volume=11 |issue=5 |pages=120–122 |url=https://books.google.com/books?id=wSYwAAAAYAAJ&pg=PA120 |doi=10.1002/andp.18020110507 |bibcode=1802AnP....11..120H |access-date=15 July 2016 |archive-date=9 May 2016 |archive-url=https://web.archive.org/web/20160509100435/https://books.google.com/books?id=wSYwAAAAYAAJ&pg=PA120 |url-status=live }}</ref> He found a new element in a mineral sample that had been sent to England from [[Connecticut]], United States in 1734 by John Winthrop F.R.S. (grandson of [[John Winthrop the Younger]]) and named the mineral ''columbite'' and the new element ''columbium'' after ''[[Columbia (name)|Columbia]]'',<ref>{{cite journal|title = Reaction of Tantalum, Columbium and Vanadium with Iodine|first = F.|last = Kòrösy|journal = Journal of the American Chemical Society|date = 1939|volume = 61|issue = 4|pages = 838–843|doi = 10.1021/ja01873a018}}</ref> the poetic name for the United States.<ref name="Noyes" /><ref name="1853 Mining Journal">{{cite journal|last=Percival|first=James|title=Middletown Silver and Lead Mines|journal=Journal of Silver and Lead Mining Operations|date=January 1853|volume=1|page=186|url=https://play.google.com/store/books/details?id=MFILAAAAYAAJ&rdid=book-MFILAAAAYAAJ&rdot=1|access-date=24 April 2013|archive-date=3 June 2013|archive-url=https://web.archive.org/web/20130603002528/https://play.google.com/store/books/details?id=MFILAAAAYAAJ&rdid=book-MFILAAAAYAAJ&rdot=1|url-status=live}}</ref><ref>{{cite journal|title = Charles Hatchett FRS (1765–1847), Chemist and Discoverer of Niobium|first = William P.|last = Griffith|author2=Morris, Peter J. T. |journal = Notes and Records of the Royal Society of London|volume = 57|issue = 3|pages = 299–316|date = 2003|jstor = 3557720|doi = 10.1098/rsnr.2003.0216|s2cid = 144857368}}</ref> However, after the 15th Conference of the Union of Chemistry in Amsterdam in 1949, the name niobium was chosen for element 41.<ref name="Contro">{{cite journal |first = Geoff|last = Rayner-Canham|author2=Zheng, Zheng |title = Naming elements after scientists: an account of a controversy|journal = Foundations of Chemistry|volume = 10|issue = 1|date = 2008|doi = 10.1007/s10698-007-9042-1|pages = 13–18|s2cid = 96082444}}</ref> The ''columbium'' discovered by Hatchett was probably a mixture of the new element with tantalum, which was first discovered in 1802 by [[Anders Gustav Ekeberg]].<ref name="Noyes">{{cite book| last = Noyes| first = William Albert| title = A Textbook of Chemistry| publisher = H. Holt & Co.| page = 523| url = https://books.google.com/books?id=UupHAAAAIAAJ&q=columbium+discovered+by+Hatchett+was+a+mixture+of+two+elements&pg=PA523| date = 1918| access-date = 2 November 2020| archive-date = 2 June 2022| archive-url = https://web.archive.org/web/20220602091834/https://books.google.com/books?id=UupHAAAAIAAJ&q=columbium+discovered+by+Hatchett+was+a+mixture+of+two+elements&pg=PA523| url-status = live}}</ref>

[[File:Anders Gustaf Ekeberg.jpg|thumb|right|Anders Gustav Ekeberg, the discoverer of tantalum]]

Subsequently, there was considerable confusion<ref name="Wolla">{{cite journal|title = On the Identity of Columbium and Tantalum|pages = 246–252|journal = Philosophical Transactions of the Royal Society|first = William Hyde|last = Wollaston|author-link = William Hyde Wollaston|doi = 10.1098/rstl.1809.0017| jstor = 107264|volume = 99|date = 1809|s2cid = 110567235}}</ref> over the difference between columbium (niobium) and the closely related tantalum. In 1809, English chemist [[William Hyde Wollaston]] compared the oxides derived from both columbium—columbite, with a density 5.918&nbsp;g/cm{{sup|3}}, and tantalum—[[tantalite]], with a density over 8&nbsp;g/cm{{sup|3}}, and concluded that the two oxides, despite the significant difference in density, were identical; thus he kept the name tantalum.<ref name="Wolla" /> This conclusion was disputed in 1846 by German chemist [[Heinrich Rose]], who argued that there were two different elements in the tantalite sample, and named them after children of [[Tantalus]]: ''niobium'' (from [[Niobe]]) and ''[[pelopium]]'' (from [[Pelops]]).<ref name="Pelop">{{cite journal|title = Ueber die Zusammensetzung der Tantalite und ein im Tantalite von Baiern enthaltenes neues Metall|pages = 317–341|journal = Annalen der Physik|author-link = Heinrich Rose|language = de|first = Heinrich|last = Rose|doi = 10.1002/andp.18441391006|url = http://gallica.bnf.fr/ark:/12148/bpt6k15148n/f327.table|volume = 139|issue = 10|date = 1844|bibcode = 1844AnP...139..317R|access-date = 31 August 2008|archive-date = 20 June 2013|archive-url = https://web.archive.org/web/20130620093605/http://gallica.bnf.fr/ark:/12148/bpt6k15148n/f327.table|url-status = live}}</ref><ref>{{cite journal|title = Ueber die Säure im Columbit von Nordamérika|language = de|pages = 572–577|first = Heinrich|last = Rose|journal = Annalen der Physik|doi = 10.1002/andp.18471460410|url = http://gallica.bnf.fr/ark:/12148/bpt6k15155x/f586.table|date = 1847|volume = 146|issue = 4|author-link = Heinrich Rose|bibcode = 1847AnP...146..572R|access-date = 31 August 2008|archive-date = 11 May 2014|archive-url = https://web.archive.org/web/20140511114909/http://gallica.bnf.fr/ark:/12148/bpt6k15155x/f586.table|url-status = live}}</ref> This confusion arose from the minimal observed differences between tantalum and niobium. The claimed new elements ''pelopium'', ''[[ilmenium]]'', and ''dianium''<ref name="Dianium">{{cite journal|title = Ueber eine eigenthümliche Säure, Diansäure, in der Gruppe der Tantal- und Niob- verbindungen|first = V.|last = Kobell|journal = Journal für Praktische Chemie|volume = 79|issue = 1|pages = 291–303|doi = 10.1002/prac.18600790145|date = 1860|url = https://zenodo.org/record/1427822|access-date = 5 October 2019|archive-date = 5 October 2019|archive-url = https://web.archive.org/web/20191005220552/https://zenodo.org/record/1427822|url-status = live}}</ref> were in fact identical to niobium or mixtures of niobium and tantalum.<ref name="Ilmen">{{cite journal|title = Tantalsäure, Niobsäure, (Ilmensäure) und Titansäure|journal = Fresenius' Journal of Analytical Chemistry|volume = 5|issue = 1|date = 1866|doi = 10.1007/BF01302537|pages = 384–389|author= Marignac, Blomstrand|author2= Deville, H. |author3= Troost, L. |author4= Hermann, R. |s2cid = 97246260}}</ref> Pure tantalum was not produced until 1903.<ref name = "Emsley"/>

=== Dubnium ===

The last element of the group, [[dubnium]], does not occur naturally and so must be synthesized in a laboratory. The first reported detection was by a team at the [[Joint Institute for Nuclear Research]] (JINR), which in 1968 had produced the new element by bombarding an [[americium]]-243 target with a beam of [[neon]]-22 ions, and reported 9.4&nbsp;MeV (with a half-life of 0.1–3 seconds) and 9.7&nbsp;MeV (''t''<sub>1/2</sub>&nbsp;>&nbsp;0.05&nbsp;s) [[alpha decay|alpha activities]] followed by alpha activities similar to those of either <sup>256</sup>103 or <sup>257</sup>103. Based on prior theoretical predictions, the two activity lines were assigned to <sup>261</sup>105 and <sup>260</sup>105, respectively.<ref name="1993 report">{{Cite journal|year=1993|title=Discovery of the Transfermium elements|url=http://s3.documentcloud.org/documents/562229/iupac1.pdf|journal=Pure and Applied Chemistry|volume=65|issue=8|pages=1757|doi=10.1351/pac199365081757|access-date=September 7, 2016|last1=Barber|first1=R. C.|last2=Greenwood|first2=N. N.|author-link2=Norman Greenwood|last3=Hrynkiewicz|first3=A. Z.|display-authors=3|last4=Jeannin|first4=Y. P|last5=Lefort|first5=M|last6=Sakai|first6=M|last7=Ulehla|first7=I|last8=Wapstra|first8=A. H|last9=Wilkinson|first9=D. H|s2cid=195819585}}</ref>

After observing the alpha decays of element 105, the researchers aimed to observe the [[spontaneous fission]] (SF) of the element and study the resulting fission fragments. They published a paper in February 1970, reporting multiple examples of two such activities, with half-lives of 14&nbsp;ms and {{val|2.2|0.5|u=s}}. They assigned the former activity to <sup>242mf</sup>Am{{efn|This notation signifies that the nucleus is a [[nuclear isomer]] that decays via spontaneous fission.}} and ascribed the latter activity to an isotope of element 105. They suggested that it was unlikely that this activity could come from a transfer reaction instead of element 105, because the yield ratio for this reaction was significantly lower than that of the <sup>242mf</sup>Am-producing transfer reaction, in accordance with theoretical predictions. To establish that this activity was not from a (<sup>22</sup>Ne,''x''n) reaction, the researchers bombarded a <sup>243</sup>Am target with <sup>18</sup>O ions; reactions producing <sup>256</sup>103 and <sup>257</sup>103 showed very little SF activity (matching the established data), and the reaction producing heavier <sup>258</sup>103 and <sup>259</sup>103 produced no SF activity at all, in line with theoretical data. The researchers concluded that the activities observed came from SF of element 105.<ref name="1993 report" />

JINR then attempted an experiment to create element 105, published in a report in May 1970. They claimed that they had synthesized more nuclei of element 105 and that the experiment confirmed their previous work. According to the paper, the isotope produced by JINR was probably <sup>261</sup>105, or possibly <sup>260</sup>105.<ref name="1993 report" /> This report included an initial chemical examination: the thermal gradient version of the gas-chromatography method was applied to demonstrate that the chloride of what had formed from the SF activity nearly matched that of [[Niobium(V) chloride|niobium pentachloride]], rather than [[hafnium tetrachloride]]. The team identified a 2.2-second SF activity in a volatile chloride portraying eka-tantalum properties, and inferred that the source of the SF activity must have been element 105.<ref name="1993 report" />

In June 1970, JINR made improvements on their first experiment, using a purer target and reducing the intensity of transfer reactions by installing a [[collimator]] before the catcher. This time, they were able to find 9.1&nbsp;MeV alpha activities with daughter isotopes identifiable as either <sup>256</sup>103 or <sup>257</sup>103, implying that the original isotope was either <sup>260</sup>105 or <sup>261</sup>105.<ref name="1993 report" />

{{multiple image
| footer = Danish nuclear physicist [[Niels Bohr]] and German nuclear chemist [[Otto Hahn]], both proposed as possible namesakes for element 105
| align = right
| direction =
| width =
| width1 = 125
| width2 = 125
| image1 = Niels Bohr.jpg
| alt1 = Photo of Niels Bohr
| caption1 =
| image2 = Otto Hahn (Nobel).jpg
| alt2 = Photo of Otto Hahn
| caption2 =
}}

A [[Transfermium Wars|controversy]] erupted on who had discovered the element, which each group suggesting its own name: the Dubna group named the element ''nielsbohrium'' after [[Niels Bohr]], while the Berkeley group named it ''hahnium'' after [[Otto Hahn]].<ref name=transuranium>{{cite book |last1=Hoffman |first1=D. C. |last2=Ghiorso |first2=A. |last3=Seaborg |first3=G. T. |title=The Transuranium People: The Inside Story |year=2000 |pages=369–399 |publisher=Imperial College Press |isbn=978-1-86094-087-3}}</ref> Eventually a joint working party of [[IUPAC]] and [[IUPAP]], the Transfermium Working Group, decided that credit for the discovery should be shared. After various compromises were attempted, where element 105 was called ''kurchatovium'', ''joliotium'' and ''hahnium'', in 1997 IUPAC officially named the element dubnium after Dubna,<ref name=97IUPAC>{{cite journal |doi =10.1351/pac199769122471 |title =Names and symbols of transfermium elements (IUPAC Recommendations 1997) |date =1997 |journal =Pure and Applied Chemistry |volume =69 |issue = 12 |pages =2471–2474|doi-access =free }}</ref><ref name="Emsley" /> and ''nielsbohrium'' was eventually simplified to ''bohrium'' and used for [[bohrium|element 107]].<ref>{{cite journal |last1=Ghiorso |first1=A. |last2=Seaborg |first2=G. T. |last3=Organessian |first3=Yu. Ts. |last4=Zvara |first4=I. |last5=Armbruster |first5=P. |last6=Hessberger |first6=F. P. |last7=Hofmann |first7=S. |last8=Leino |first8=M. |last9=Munzenberg |first9=G. |last10=Reisdorf |first10=W. |last11=Schmidt |first11=K.-H. |year=1993 |title=Responses on 'Discovery of the transfermium elements' by Lawrence Berkeley Laboratory, California; Joint Institute for Nuclear Research, Dubna; and Gesellschaft fur Schwerionenforschung, Darmstadt followed by reply to responses by the Transfermium Working Group |journal=Pure and Applied Chemistry |volume=65 |issue=8 |pages=1815–1824 |doi=10.1351/pac199365081815 |doi-access=free}}</ref><ref name="IUPAC97">{{Cite journal |author=Commission on Nomenclature of Inorganic Chemistry |date=1997 |title=Names and symbols of transfermium elements (IUPAC Recommendations 1997) |url=http://publications.iupac.org/pac/pdf/1997/pdf/6912x2471.pdf |url-status=live |journal=Pure and Applied Chemistry |volume=69 |issue=12 |pages=2471–2474 |doi=10.1351/pac199769122471 |archive-url=https://web.archive.org/web/20211011132719/http://publications.iupac.org/pac/pdf/1997/pdf/6912x2471.pdf |archive-date=2021-10-11 |access-date=2023-07-11}}</ref>

== Chemical properties ==

Like other groups, the members of this family show patterns in its [[electron configuration]], especially the outermost shells. (The expected 4d<sup>3</sup> 5s<sup>2</sup> configuration for niobium is a very low-lying excited state at about 0.14&nbsp;eV.)<ref>[https://physics.nist.gov/PhysRefData/ASD/levels_form.html NIST Atomic Spectra Database]</ref>

{| class="wikitable" style="white-space:nowrap;"
|+
! colspan=4 | [[Electron configuration]]s of group 5 elements
|-
! {{abbr|1=[[Atomic number|''Z'']]|2=Atomic number}} !! [[Chemical element|Element]] !! Electrons per [[Electron shell|shell]] !! [[Electron configuration]]
|-
| style="text-align:right" | 23 || V, vanadium || {{mono|2, 8, 11, 2}}    || {{mono|1=[Ar] &nbsp;&nbsp;<sup>&nbsp;&nbsp;</sup> 3d<sup>3</sup> 4s<sup>2</sup>}}
|-
| style="text-align:right" | 41 || Nb, niobium   || {{mono|2, 8, 18, 12, 1}}|| {{mono|1=[Kr] &nbsp;&nbsp;<sup>&nbsp;&nbsp;</sup> 4d<sup>4</sup> 5s<sup>1</sup>}}
|-
| style="text-align:right" | 73 || Ta, tantalum || {{mono|2, 8, 18, 32, 11, 2}} ||  {{mono|1=[Xe] 4f<sup>14</sup> 5d<sup>3</sup> 6s<sup>2</sup>}}
|-
| style="text-align:right" | 105 || Db, dubnium || {{mono|2, 8, 18, 32, 32, 11, 2}} || {{mono|1=[Rn] 5f<sup>14</sup> 6d<sup>3</sup> 7s<sup>2</sup>}}
|}

Most of the chemistry has been observed only for the first three members of the group (the chemistry of dubnium is not very established, but what is known appears to match expectations for a heavier congener of tantalum). All the elements of the group are reactive metals with a high melting points (1910&nbsp;°C, 2477&nbsp;°C, 3017&nbsp;°C). The reactivity is not always obvious due to the rapid formation of a stable oxide layer, which prevents further reactions, similarly to trends in group 3 or group 4. The metals form different oxides: vanadium forms [[vanadium(II) oxide]], [[vanadium(III) oxide]], [[vanadium(IV) oxide]] and [[vanadium(V) oxide]], niobium forms [[niobium(II) oxide]], [[niobium(IV) oxide]] and [[niobium(V) oxide]], but out of tantalum oxides only [[tantalum(V) oxide]] is characterized. Metal(V) oxides are generally nonreactive and act like acids rather than bases, but the lower oxides are less stable. They, however, have some unusual properties for oxides, such as high electric conductivity.<ref name="HollemanAF" />

All three elements form various [[inorganic chemistry|inorganic compounds]], generally in the oxidation state of +5. Lower oxidation states are also known, but in all elements other than vanadium,<ref name="HollemanAF2">{{cite book |last=Holleman |first=Arnold F. |title=Lehrbuch der Anorganischen Chemie |author2=Wiberg, Egon |author3=Wiberg, Nils |date=1985 |publisher=Walter de Gruyter |isbn=978-3-11-007511-3 |edition=91–100 |pages=1071–1075 |language=de |chapter=Vanadium}}</ref> they are less stable, decreasing in stability with atomic mass increase.<ref name="Greenwood956" />

=== Compounds ===

==== Oxides ====
Vanadium forms oxides in the +2, +3, +4 and +5 [[oxidation state]]s, forming [[vanadium(II) oxide]] (VO), [[vanadium(III) oxide]] (V<sub>2</sub>O<sub>3</sub>), [[vanadium(IV) oxide]] (VO<sub>2</sub>) and [[vanadium(V) oxide]] (V<sub>2</sub>O<sub>5</sub>). Vanadium(V) oxide or vanadium pentoxide is the most common, being precursor to most alloys and compounds of vanadium, and is also a widely used industrial catalyst.<ref name=Ullmann>{{Cite book|doi = 10.1002/14356007.a27_367|chapter = Vanadium and Vanadium Compounds|title = Ullmann's Encyclopedia of Industrial Chemistry|year = 2000|last1 = Bauer|first1 = Günter|last2 = Güther|first2 = Volker|last3 = Hess|first3 = Hans|last4 = Otto|first4 = Andreas|last5 = Roidl|first5 = Oskar|last6 = Roller|first6 = Heinz|last7 = Sattelberger|first7 = Siegfried|isbn = 3527306730}}</ref>

Niobium forms oxides in the oxidation states +5 ([[Niobium pentoxide|{{chem2|Nb2O5}}]]),<ref>{{Cite web|url=https://pubchem.ncbi.nlm.nih.gov/compound/Niobium_oxide#section=Top|title=Niobium oxide {{!}} Nb2O5 – PubChem|last=Pubchem|website=pubchem.ncbi.nlm.nih.gov|access-date=29 June 2016|archive-date=16 August 2016|archive-url=https://web.archive.org/web/20160816070526/https://pubchem.ncbi.nlm.nih.gov/compound/Niobium_oxide#section=Top|url-status=live}}</ref> +4 ([[Niobium dioxide|{{chem2|NbO2}}]]), and the rarer oxidation state, +2 ([[niobium monoxide|NbO]]).<ref name=Greenwood&Earnshaw2nd /> Most common is the pentoxide, also being precursor to almost all niobium compounds and alloys.<ref name="HollemanAF" /><ref name="Cardarelli">{{cite book|first = Francois|last = Cardarelli|date = 2008|title = Materials Handbook |publisher = Springer London|isbn = 978-1-84628-668-1}}</ref>

[[Tantalum pentoxide]] (Ta<sub>2</sub>O<sub>5</sub>) is the most important compound from the perspective of applications. Oxides of tantalum in lower oxidation states are numerous, including many [[defect structure]]s, and are lightly studied or poorly characterized.<ref name="Greenwood&Earnshaw2nd">{{Greenwood&Earnshaw2nd}}</ref>
<!-- speculations about dubnium oxides -->

==== Oxyanions ====

[[File:decavanadate polyhedra.png|thumb|The [[decavanadate]] structure]]
<!-- [[File:Ammonium-metavanadate-chains-3D.png|thumb|upright|Metavanadate chains]] -->In aqueous solution, vanadium(V) forms an extensive family of [[oxyanion]]s as established by [[Vanadium-51 nuclear magnetic resonance|<sup>51</sup>V NMR spectroscopy]].<ref name="Rehder">{{cite book |doi=10.1016/S0066-4103(07)62002-X|title=Vanadium-51 NMR|series=Annual Reports on NMR Spectroscopy|year=2007|last1=Rehder|first1=D.|last2=Polenova|first2=T.|last3=Bühl|first3=M.|volume=62|pages=49–114|isbn=9780123739193}}</ref> The interrelationships in this family are described by the [[predominance diagram]], which shows at least 11 species, depending on pH and concentration.<ref>{{Greenwood&Earnshaw|page=984}}</ref> The tetrahedral orthovanadate ion, {{chem|VO|4|3−}}, is the principal species present at pH 12–14. Similar in size and charge to phosphorus(V), vanadium(V) also parallels its chemistry and crystallography. [[Sodium orthovanadate|Orthovanadate]] V{{chem|O|4|3−}} is used in [[protein crystallography]]<ref>{{cite journal|volume= 577|issue= 3|doi= 10.1016/j.febslet.2004.10.022|pmid= 15556602|date= 2004|title= The power of vanadate in crystallographic investigations of phosphoryl transfer enzymes|first1= Irmgard|last1= Sinning|journal= FEBS Letters|last2= Hol|first2= Wim G. J.|pages= 315–21|s2cid= 8328704|doi-access= free|bibcode= 2004FEBSL.577..315D}}</ref> to study the [[biochemistry]] of phosphate.<ref>{{cite journal|volume= 181|pmc= 1161148|date= 1979|title= Inhibition of human alkaline phosphatases by vanadate|first= Lorne E.|last= Seargeant|author2=Stinson, Robert A. |journal= Biochemical Journal|pmid=486156|issue=1|pages= 247–50|doi= 10.1042/bj1810247}}</ref> Beside that, this anion also has been shown to interact with activity of some specific enzymes.<ref>{{Cite journal |last1=Crans |first1=Debbie C. |last2=Simone |first2=Carmen M. |date=1991-07-09 |title=Nonreductive interaction of vanadate with an enzyme containing a thiol group in the active site: glycerol-3-phosphate dehydrogenase |url=https://pubs.acs.org/doi/abs/10.1021/bi00241a015 |journal=Biochemistry |language=en |volume=30 |issue=27 |pages=6734–6741 |doi=10.1021/bi00241a015 |pmid=2065057 |issn=0006-2960|url-access=subscription }}</ref><ref>{{Cite journal |last1=Karlish |first1=S. J. D. |last2=Beaugé |first2=L. A. |last3=Glynn |first3=I. M. |date=Nov 1979 |title=Vanadate inhibits (Na+ + K+)ATPase by blocking a conformational change of the unphosphorylated form |url=https://www.nature.com/articles/282333a0 |journal=Nature |language=en |volume=282 |issue=5736 |pages=333–335 |doi=10.1038/282333a0 |pmid=228199 |bibcode=1979Natur.282..333K |s2cid=4341480 |issn=1476-4687|url-access=subscription }}</ref> The tetrathiovanadate [VS<sub>4</sub>]<sup>3−</sup> is analogous to the orthovanadate ion.<ref>{{Greenwood&Earnshaw|page=988}}</ref>

At lower pH values, the monomer [HVO<sub>4</sub>]<sup>2−</sup> and dimer [V<sub>2</sub>O<sub>7</sub>]<sup>4−</sup> are formed, with the monomer predominant at vanadium concentration of less than c. 10<sup>−2</sup>M (pV > 2, where pV is equal to the minus value of the logarithm of the total vanadium concentration/M). The formation of the divanadate ion is analogous to the formation of the [[dichromate]] ion. As the pH is reduced, further protonation and condensation to [[vanadate|polyvanadates]] occur: at pH 4–6 [H<sub>2</sub>VO<sub>4</sub>]<sup>−</sup> is predominant at pV greater than ca. 4, while at higher concentrations trimers and tetramers are formed. Between pH 2–4 [[decavanadate]] predominates, though its formation from orthovanadate is optimized at pH 4–7, represented by this reaction:<ref name="one">{{cite book |author1=Johnson, G. |title=Inorganic Syntheses |author2=Murmann, R. K. |date=1979 |isbn=978-0-471-04542-7 |volume=19 |pages=140–145 |chapter=Sodium and Ammonium Decayanadates(V) |doi=10.1002/9780470132500.ch32}}</ref>
:{{Chem2|10 Na3[VO4] + 24 HOAc → Na6[V10O28] + 12 H2O + 24 NaOAc}}

In decavanadate, each V(V) center is surrounded by six oxide [[ligand]]s.<ref name="HollemanAF" /> Vanadic acid, H<sub>3</sub>VO<sub>4</sub> exists only at very low concentrations because protonation of the tetrahedral species [H<sub>2</sub>VO<sub>4</sub>]<sup>−</sup> results in the preferential formation of the octahedral [VO<sub>2</sub>(H<sub>2</sub>O)<sub>4</sub>]<sup>+</sup> species. In strongly acidic solutions, pH&nbsp;<&nbsp;2, [VO<sub>2</sub>(H<sub>2</sub>O)<sub>4</sub>]<sup>+</sup> is the predominant species, while the oxide V<sub>2</sub>O<sub>5</sub> precipitates from solution at high concentrations.<ref>{{Cite journal |last=Sadoc |first=Aymeric |last2=Messaoudi |first2=Sabri |last3=Furet |first3=Eric |last4=Gautier |first4=Régis |last5=Le Fur |first5=Eric |last6=le Pollès |first6=Laurent |last7=Pivan |first7=Jean-Yves |date=2007-06-01 |title=Structure and Stability of VO 2 + in Aqueous Solution: A Car−Parrinello and Static ab Initio Study |url=https://pubs.acs.org/doi/10.1021/ic0614519 |journal=Inorganic Chemistry |language=en |volume=46 |issue=12 |pages=4835–4843 |doi=10.1021/ic0614519 |issn=0020-1669|url-access=subscription }}</ref> The oxide is formally the [[acidic oxide|acid anhydride]] of vanadic acid. The structures of many [[vanadate]] compounds have been determined by X-ray crystallography.<ref>{{Cite journal |last=Davies |first=Douglas R. |last2=Hol |first2=Wim G.J. |date=2004-11-19 |title=The power of vanadate in crystallographic investigations of phosphoryl transfer enzymes |url=https://febs.onlinelibrary.wiley.com/doi/10.1016/j.febslet.2004.10.022 |journal=FEBS Letters |language=en |volume=577 |issue=3 |pages=315–321 |doi=10.1016/j.febslet.2004.10.022 |issn=0014-5793}}</ref>

[[File:VinwaterPourbaixdiagram2.svg|thumb|right|The [[Pourbaix diagram]] for vanadium in water, which shows the [[redox]] potentials between various vanadium species in different oxidation states.<ref>{{cite journal|journal= Electrochimica Acta|volume= 42|date= 1997|pages= 579–586|doi= 10.1016/S0013-4686(96)00202-2|title= Electrochemical behavior of vanadium in aqueous solutions of different pH|first= F. M.|last= Al-Kharafi|author2=Badawy, W. A. |issue= 4}}</ref>]]

Vanadium(V) forms various peroxo complexes, most notably in the active site of the vanadium-containing [[bromoperoxidase]] enzymes. The species VO(O)<sub>2</sub>(H<sub>2</sub>O)<sub>4</sub><sup>+</sup> is stable in acidic solutions. In alkaline solutions, species with 2, 3 and 4 peroxide groups are known; the last forms violet salts with the formula M<sub>3</sub>V(O<sub>2</sub>)<sub>4</sub> nH<sub>2</sub>O (M= Li, Na, etc.), in which the vanadium has an 8-coordinate dodecahedral structure.<ref>{{Greenwood&Earnshaw}}, p994.</ref><ref>{{cite book|date=1992|url=https://books.google.com/books?id=Lmt3x9CyfLgC&pg=PA128|page=128|title=Catalytic oxidations with hydrogen peroxide as oxidant|author=Strukul, Giorgio|publisher=Springer|isbn=978-0-7923-1771-5}}</ref>

Niobates are generated by dissolving the pentoxide in [[Base (chemistry)|basic]] [[hydroxide]] solutions or by melting it in alkali metal oxides. Examples are [[lithium niobate]] ({{chem2|LiNbO3}}) and lanthanum niobate ({{chem2|LaNbO4}}). In the lithium niobate is a trigonally distorted [[Perovskite (structure)|perovskite]]-like structure, whereas the lanthanum niobate contains lone {{chem|NbO|4|3-}} ions.<ref name="HollemanAF" />

Tantalates, compounds containing [TaO<sub>4</sub>]<sup>3−</sup> or [TaO<sub>3</sub>]<sup>−</sup> are numerous. [[Lithium tantalate]] (LiTaO<sub>3</sub>) adopts a perovskite structure. [[Lanthanum]] tantalate (LaTaO<sub>4</sub>) contains isolated {{chem|TaO|4|3−}} tetrahedra.<ref name="HollemanAF" />

==== Halides and their derivatives ====

Twelve binary [[halides]], compounds with the formula VX<sub>n</sub> (n=2...5), are known. VI<sub>4</sub>, VCl<sub>5</sub>, VBr<sub>5</sub>, and VI<sub>5</sub> do not exist or are extremely unstable; the only known pure V{{Sup|5+}} halide compound is {{Chem2|VF5|link=vanadium pentafluoride}}.<ref>{{Citation |title=Vanadium series products and functional materials |date=2021 |work=Vanadium |pages=395–413 |url=https://linkinghub.elsevier.com/retrieve/pii/B9780128188989000140 |access-date=2024-11-11 |publisher=Elsevier |language=en |doi=10.1016/b978-0-12-818898-9.00014-0 |isbn=978-0-12-818898-9|url-access=subscription }}</ref> In combination with other reagents, [[vanadium(IV) chloride|VCl<sub>4</sub>]] is used as a catalyst for polymerization of [[diene]]s. Like all binary halides, those of vanadium are [[Lewis acid]]ic, especially those of V(IV) and V(V). Many of the halides form octahedral complexes with the formula VX<sub>''n''</sub>L<sub>6−''n''</sub> (X= halide; L= other ligand).<ref>{{Cite journal |last=VonDreele |first=Robert B. |last2=Fay |first2=Robert C. |date=November 1972 |title=Octahedral vanadium(IV) complexes. Synthesis and stereochemistry of vanadium(IV) .beta.-diketonates |url=https://pubs.acs.org/doi/abs/10.1021/ja00777a052 |journal=Journal of the American Chemical Society |language=en |volume=94 |issue=22 |pages=7935–7936 |doi=10.1021/ja00777a052 |issn=0002-7863|url-access=subscription }}</ref><ref>{{Cite journal |last=Halepoto |first=Dost M |last2=Larkworthy |first2=Leslie F |last3=Povey |first3=David C |last4=Smith |first4=Gallienus W |last5=Ramdas |first5=Vijayalaksmi |date=June 1995 |title=Some complex halides of vanadium(II) and vanadium(III). The crystal and molecular structure of tetrakis(methylammonium) hexachlorovanadate(III) chloride |url=https://linkinghub.elsevier.com/retrieve/pii/0277538794004139 |journal=Polyhedron |language=en |volume=14 |issue=11 |pages=1453–1460 |doi=10.1016/0277-5387(94)00413-9|url-access=subscription }}</ref>

Many vanadium [[oxyhalide]]s (formula VO<sub>m</sub>X<sub>n</sub>) are known.<ref>{{Greenwood&Earnshaw|page=993}}</ref> The oxytrichloride and oxytrifluoride ([[vanadium oxytrichloride|VOCl<sub>3</sub>]] and [[Vanadium(V) oxytrifluoride|VOF<sub>3</sub>]]) are the most widely studied. Akin to POCl<sub>3</sub>, they are volatile, adopt tetrahedral structures in the gas phase, and are Lewis acidic.<ref name=":0">{{Cite book |url=https://www.degruyter.com/document/doi/10.1515/9783110495904/html |title=Nebengruppenelemente, Lanthanoide, Actinoide, Transactinoide |date=2016-12-19 |publisher=De Gruyter |isbn=978-3-11-049590-4 |editor-last=Holleman |editor-first=Arnold F. |pages=1819-1825 |language=de |chapter=Kapitel XXVI. Die Vanadiumgruppe |doi=10.1515/9783110495904}}</ref>

[[File:Niobium pentachloride solid.jpg|thumb|right|upright=0.8|A very pure sample of niobium pentachloride|alt=Watch glass on a black surface with a small portion of yellow crystals]]
[[File:Niobium-pentachloride-from-xtal-3D-balls.png|thumb|right|upright=0.8|Ball-and-stick model of [[niobium pentachloride]], which exists as a [[Dimer (chemistry)|dimer]]]]

Niobium forms halides in the oxidation states of +5 and +4 as well as diverse [[nonstoichiometric compound|substoichiometric compounds]].<ref name="HollemanAF" /><ref name="Aguly">{{cite book|first = Anatoly|last = Agulyansky|title = The Chemistry of Tantalum and Niobium Fluoride Compounds|pages = 1–11|publisher = Elsevier|date=2004| isbn = 978-0-444-51604-6}}</ref> The pentahalides ({{chem|NbX|5}}) feature octahedral Nb centres. Niobium pentafluoride ({{chem2|NbF5}}) is a white solid with a melting point of 79.0&nbsp;°C and [[niobium pentachloride]] ({{chem2|NbCl5}}) is yellow (see image at left) with a melting point of 203.4&nbsp;°C. Both are [[hydrolyzed]] to give oxides and oxyhalides, such as {{chem2|NbOCl3}}. The pentachloride is a versatile reagent used to generate the [[organometallic]] compounds, such as [[niobocene dichloride]] ({{chem|(C|5|H|5|)|2|NbCl|2}}).<ref>{{cite book|author = Lucas, C. R. |author2 = Labinger, J. A. |author3 = Schwartz, J. |title = Inorganic Syntheses |chapter = Dichlorobis(η <sup>5</sup> -Cyclopentadienyl) Niobium(IV) |editor1-link=Robert Angelici|editor-first = Robert J.|editor-last = Angelici|date = 1990|volume = 28|pages = 267–270|isbn = 978-0-471-52619-3|doi = 10.1002/9780470132593.ch68|location = New York}}</ref> The tetrahalides ({{chem|NbX|4}}) are dark-coloured polymers with Nb-Nb bonds; for example, the black [[hygroscopic]] niobium tetrafluoride ({{chem2|NbF4}})<ref>{{Cite journal |last=Gortsema |first=F. P. |last2=Didchenko |first2=R. |date=February 1965 |title=The Preparation and Properties of Niobium Tetrafluoride and Oxyfluorides |url=https://pubs.acs.org/doi/abs/10.1021/ic50024a012 |journal=Inorganic Chemistry |language=en |volume=4 |issue=2 |pages=182–186 |doi=10.1021/ic50024a012 |issn=0020-1669|url-access=subscription }}</ref> and dark violet niobium tetrachloride ({{chem2|NbCl4}}).<ref name="Macintyre">Macintyre, J.E.; Daniel, F.M.; Chapman and Hall; Stirling, V.M.  Dictionary of Inorganic Compounds.  1992, Cleveland, OH: CRC Press, p. 2957</ref>

Anionic halide compounds of niobium are well known, owing in part to the [[Lewis acid]]ity of the pentahalides. The most important is [NbF<sub>7</sub>]<sup>2−</sup>, an intermediate in the separation of Nb and Ta from the ores.<ref name="ICE">{{cite journal|title = Staff-Industry Collaborative Report: Tantalum and Niobium|author=Soisson, Donald J.|author2=McLafferty, J. J.|author3=Pierret, James A.| journal = Industrial and Engineering Chemistry|date = 1961|volume = 53|issue = 11|pages = 861–868|doi = 10.1021/ie50623a016}}</ref> This heptafluoride tends to form the oxopentafluoride more readily than does the tantalum compound. Other halide complexes include octahedral [{{chem2|NbCl6}}]{{sup|−}}:
:{{chem2|Nb2Cl10}} + 2 Cl{{sup|−}} → 2 [{{chem2|NbCl6}}]{{sup|−}}

As with other metals with low atomic numbers, a variety of reduced halide cluster ions is known, the prime example being [{{chem2|Nb6Cl18}}]{{sup|4−}}.<ref name="Greenwood&Earnshaw2nd"/>

Tantalum halides span the oxidation states of +5, +4, and +3. [[Tantalum pentafluoride]] (TaF<sub>5</sub>) is a white solid with a melting point of 97.0&nbsp;°C. The anion [TaF<sub>7</sub>]<sup>2-</sup> is used for its separation from niobium.<ref name="ICE" /> The chloride [[tantalum(V) chloride|{{chem|TaCl|5}}]], which exists as a dimer, is the main reagent in synthesis of new Ta compounds. It hydrolyzes readily to an [[oxychloride]]. The lower halides {{chem|TaX|4}} and {{chem|TaX|3}}, feature Ta-Ta bonds.<ref name="HollemanAF" /><ref name="Aguly" />

== Physical properties ==

The trends in group 5 follow those of the other early d-block groups and reflect the addition of a filled f-shell into the core in passing from the fifth to the sixth period. All the stable members of the group are silvery-blue [[refractory metal]]s, though impurities of [[carbon]], [[nitrogen]], and oxygen make them brittle.<ref name=Greenwood956>{{Greenwood&Earnshaw2nd|page=956-958}}</ref> They all crystallize in the [[cubic crystal system|body-centered cubic]] structure at room temperature,<ref name=Greenwood946>{{Greenwood&Earnshaw2nd|page=946-948}}</ref> and dubnium is expected to do the same.<ref name=bcc>{{cite journal|doi=10.1103/PhysRevB.84.113104|title=First-principles calculation of the structural stability of 6d transition metals|year=2011|last1=Östlin|first1=A.|last2=Vitos|first2=L.|journal=Physical Review B|volume=84|issue=11|page=113104 |bibcode=2011PhRvB..84k3104O }}</ref>

The table below is a summary of the key physical properties of the group 5 elements. The question-marked value is predicted.<ref name=Haire/>

{| class="wikitable centered plainrowheaders" style="text-align:center;"
|+Properties of the group 5 elements | Properties of the group 5 elements
! scope="col" | Name
! scope="col" | V, [[vanadium]]
! scope="col" | Nb, [[niobium]]
! scope="col" | Ta, [[tantalum]]
! scope="col" | Db, [[dubnium]]
|-
! scope="row" |[[Melting point]]
| 2183 K (1910&nbsp;°C) || 2750 K (2477&nbsp;°C) || 3290 K (3017&nbsp;°C) || {{Unknown}}
|-
! scope="row" |[[Boiling point]]
| 3680 K (3407&nbsp;°C) || 5017 K (4744&nbsp;°C) || 5731 K (5458&nbsp;°C) || {{Unknown}}
|-
! scope="row" |[[Density]]
| 6.11&nbsp;g·cm<sup>−3</sup> || 8.57&nbsp;g·cm<sup>−3</sup> || 16.69&nbsp;g·cm<sup>−3</sup> || 21.6&nbsp;g·cm<sup>−3</sup>?<ref name=density>{{cite journal |last1=Gyanchandani |first1=Jyoti |last2=Sikka |first2=S. K. |title=Physical properties of the 6 d -series elements from density functional theory: Close similarity to lighter transition metals |journal=Physical Review B |date=10 May 2011 |volume=83 |issue=17 |pages=172101 |doi=10.1103/PhysRevB.83.172101|bibcode=2011PhRvB..83q2101G }}</ref><ref name=kratz>{{cite book |last1=Kratz |last2=Lieser |title=Nuclear and Radiochemistry: Fundamentals and Applications |date=2013 |page=631 |edition=3rd}}</ref>
|-
! scope="row" |Appearance
| blue-silver-gray metal || grayish metallic, blue when oxidized ||  gray blue || {{Unknown}}
|-
! scope="row" |[[Atomic radius]]
|  135 pm || 146 pm || 146 pm || 139 pm
|}

=== Vanadium ===

Vanadium is an average-hard, [[ductility|ductile]], steel-blue metal. It is electrically [[conductive]] and thermally [[thermal insulation|insulating]]. Some sources describe vanadium as "soft", perhaps because it is ductile, [[malleable]], and not [[brittle]].<ref>{{cite book|author=George F. Vander Voort|title=Metallography, principles and practice|url=https://books.google.com/books?id=GRQC8zYqtBIC&pg=PA137|access-date=17 September 2011|date=1984|publisher=ASM International|isbn=978-0-87170-672-0|pages=137–}}</ref><ref>{{cite book|last=Cardarelli|first=François|title=Materials handbook: a concise desktop reference|url=https://books.google.com/books?id=PvU-qbQJq7IC&pg=PA338|access-date=17 September 2011|date=2008|publisher=Springer|isbn=978-1-84628-668-1|pages=338–}}</ref> Vanadium is harder than most metals and steels (see [[Hardnesses of the elements (data page)]] and [[iron#Mechanical properties|iron]]). It has good resistance to [[corrosion]] and it is stable against [[alkali]]s and [[sulfuric acid|sulfuric]] and [[hydrochloric acid]]s.<ref name="HollemanAF">{{cite book|publisher= Walter de Gruyter|date= 1985|edition= 91–100|pages= 1071–1075|isbn= 978-3-11-007511-3|title= Lehrbuch der Anorganischen Chemie|first= Arnold F.|last= Holleman|author2= Wiberg, Egon|author3= Wiberg, Nils|chapter= Vanadium |language= de}}</ref> It is [[oxidation|oxidized]] in air at about 933&nbsp;[[Kelvin|K]] (660&nbsp;°C, 1220&nbsp;°F), although an oxide [[passivation (chemistry)|passivation]] layer forms even at room temperature.<ref>{{Cite journal |last=Klinser |first=Gregor |last2=Zettl |first2=Roman |last3=Wilkening |first3=Martin |last4=Krenn |first4=Heinz |last5=Hanzu |first5=Ilie |last6=Würschum |first6=Roland |date=2019 |title=Redox processes in sodium vanadium phosphate cathodes – insights from operando magnetometry |url=https://xlink.rsc.org/?DOI=C9CP04045E |journal=Physical Chemistry Chemical Physics |language=en |volume=21 |issue=36 |pages=20151–20155 |doi=10.1039/C9CP04045E |issn=1463-9076|doi-access=free }}</ref>

=== Niobium ===

Niobium is a [[lustre (mineralogy)|lustrous]], grey, [[ductility|ductile]], [[paramagnetism|paramagnetic]] [[metal]] in group 5 of the [[periodic table]] (see table), with an electron configuration in the outermost [[electron shell|shells]] atypical for group 5. Similarly atypical configurations occur in the neighborhood of [[ruthenium]] (44) and [[rhodium]] (45).<ref>{{Cite journal |last=Scerri |first=Eric R. |date=April 2019 |title=Five ideas in chemical education that must die |url=http://link.springer.com/10.1007/s10698-018-09327-y |journal=Foundations of Chemistry |language=en |volume=21 |issue=1 |pages=61–69 |doi=10.1007/s10698-018-09327-y |issn=1386-4238|url-access=subscription }}</ref>

Although it is thought to have a [[body-centered cubic]] crystal structure from absolute zero to its melting point, high-resolution measurements of the thermal expansion along the three crystallographic axes reveal anisotropies which are inconsistent with a cubic structure.<ref>{{cite journal |last1=Bollinger |first1=R. K. |last2=White |first2=B. D. |last3=Neumeier |first3=J. J. |last4=Sandim |first4=H. R. Z. |last5=Suzuki |first5=Y. |last6=dos Santos |first6=C. A. M. |last7=Avci |first7=R. |last8=Migliori |first8=A. |last9=Betts |first9=J. B. |date=2011 |title=Observation of a Martensitic Structural Distortion in V, Nb, and Ta |journal=Physical Review Letters |volume=107 |issue=7 |pages=075503 |doi=10.1103/PhysRevLett.107.075503 |bibcode=2011PhRvL.107g5503B |pmid=21902404|doi-access=free }}</ref> <!-- Therefore, further research and discovery in this area is expected. -->

Niobium becomes a [[superconductor]] at [[cryogenics|cryogenic]] temperatures. At atmospheric pressure, it has the highest critical temperature of the elemental superconductors at 9.2&nbsp;[[Kelvin|K]].<ref name="Pein">{{cite journal|title = A Superconducting Nb<sub>3</sub>Sn Coated Multicell Accelerating Cavity|first = M.|last = Peiniger|author2=Piel, H. |journal = IEEE Transactions on Nuclear Science|date= 1985|volume= 32|issue = 5|doi = 10.1109/TNS.1985.4334443|pages = 3610–3612|bibcode = 1985ITNS...32.3610P |s2cid = 23988671}}</ref> Niobium has the greatest [[superconductor#Meissner effect|magnetic penetration depth]] of any element.<ref name="Pein" /> In addition, it is one of the three elemental [[Type II superconductor]]s, along with [[vanadium]] and [[technetium]]. The superconductive properties are strongly dependent on the purity of the niobium metal.<ref name="Moura">{{cite journal|title=Melting And Purification of Niobium|first=Hernane R.|last = Salles Moura|author2=Louremjo de Moura, Louremjo |journal=AIP Conference Proceedings|volume=927|date=2007|issue=927|pages=165–178|doi=10.1063/1.2770689|bibcode=2007AIPC..927..165M}}</ref>

When very pure, it is comparatively soft and ductile, but impurities make it harder.<ref name="Nowak">{{cite journal|title=Niobium Compounds: Preparation, Characterization, and Application in Heterogeneous Catalysis|author=Nowak, Izabela|author2=Ziolek, Maria|journal=Chemical Reviews|date=1999|volume=99|issue=12|pages=3603–3624|doi=10.1021/cr9800208|pmid=11849031}}</ref><!--awkward; this either contains redundancy or is leaving something out-->

The metal has a low [[Neutron capture#Capture cross section|capture cross-section]] for thermal [[neutron]]s;<ref>{{cite journal|title = Columbium Alloys Today|author=Jahnke, L. P.|author2=Frank, R. G.|author3=Redden, T. K.|date = 1960|journal = Metal Progr.|volume = 77|issue = 6|pages = 69–74|osti = 4183692}}</ref> thus it is used in the nuclear industries where neutron transparent structures are desired.<ref>{{cite journal|first = A. V.|last = Nikulina|title = Zirconium-Niobium Alloys for Core Elements of Pressurized Water Reactors|journal = Metal Science and Heat Treatment|volume = 45|issue = 7–8|date = 2003|doi = 10.1023/A:1027388503837|pages = 287–292|bibcode = 2003MSHT...45..287N|s2cid = 134841512}}</ref>

=== Tantalum ===

Tantalum is dark (blue-gray),<ref>{{cite book | chapter = Tantalum | chapter-url = https://books.google.com/books?id=5o3Lr2Swz8sC&pg=PA204 | isbn = 978-0-86516-573-1 | title = Classical Mythology & More: A Reader Workbook | author1 = Colakis, Marianthe | author2 = Masello, Mary Joan | date = 2007-06-30| publisher=Bolchazy-Carducci Publishers }}</ref> 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 among the elements only by [[tungsten]],<ref name="desu">{{cite book |author=Hammond, C. R. |url=https://archive.org/details/crchandbookofche81lide |title=The Elements, in Handbook of Chemistry and Physics |date=2004 |publisher=CRC press |isbn=978-0-8493-0485-9 |edition=81st |url-access=registration}}</ref> [[rhenium]]<ref name="Zhang2011">{{Cite journal |last=Zhang |first=Yiming |date=2011-01-11 |title=Corrected Values for Boiling Points and Enthalpies of Vaporization of Elements in Handbooks |url=https://www.researchgate.net/publication/231538496 |journal=Journal of Chemical & Engineering Data |volume=56 |url-access=<!--WP:URLACCESS-->}}</ref> [[osmium]],<ref>{{cite book |last1=Rumble |first1=John R. |title=CRC Handbook of Chemistry and Physics: A Ready Reference Book of Chemical and Physical Data |last2=Bruno |first2=Thomas J. |last3=Doa |first3=Maria J. |date=2022 |publisher=CRC Press |isbn=978-1-032-12171-0 |edition=103rd |location=Boca Raton, FL |page=40 |chapter=Section 4: Properties of the Elements and Inorganic Compounds}}</ref> and [[carbon]].<ref name="triple">{{cite journal |last=Greenville Whittaker |first=A. |date=1978 |title=The controversial carbon solid−liquid−vapour triple point |journal=Nature |volume=276 |issue=5689 |pages=695–696 |bibcode=1978Natur.276..695W |doi=10.1038/276695a0 |s2cid=4362313}}</ref>    

Tantalum exists in two crystalline phases, alpha and beta. The alpha phase is relatively [[Ductility|ductile]] and soft; it has [[body-centered cubic]] structure ([[space group]] ''Im3m'', lattice constant ''a'' = 0.33058&nbsp;nm), [[Knoop hardness test|Knoop hardness]] 200–400 HN and electrical resistivity 15–60 μΩ⋅cm. The beta phase is hard and brittle; its crystal symmetry is [[tetragonal]] (space group ''P42/mnm'', ''a'' = 1.0194&nbsp;nm, ''c'' = 0.5313&nbsp;nm), Knoop hardness is 1000–1300 HN and electrical resistivity is relatively high at 170–210 μΩ⋅cm. The beta phase is metastable and converts to the alpha phase upon heating to 750–775&nbsp;°C. Bulk tantalum is almost entirely alpha phase, and the beta phase usually exists as thin films<ref>{{cite journal|title=Electronic structure of β-Ta films from X-ray photoelectron spectroscopy and first-principles calculations|date=2019|last1=Magnuson|first1=M.|journal=Applied Surface Science|volume=470|pages=607–612|last2=Greczynski|first2=G.|last3=Eriksson|first3=F.|last4=Hultman|first4=L.|last5=Hogberg|first5=H.|doi=10.1016/j.apsusc.2018.11.096|url=http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-152876|bibcode=2019ApSS..470..607M|s2cid=54079998}}</ref> obtained by magnetron
[[sputtering]], [[chemical vapor deposition]] or [[Electrochemistry|electrochemical deposition]] from a [[Eutectic system|eutectic]] molten salt solution.<ref>{{cite journal|doi=10.1016/j.surfcoat.2003.06.008|title=Texture, structure and phase transformation in sputter beta tantalum coating|date=2004|last1=Lee|first1=S.|journal=Surface and Coatings Technology|volume=177– 178|page=44|last2=Doxbeck|first2=M.|last3=Mueller|first3=J.|last4=Cipollo|first4=M.|last5=Cote|first5=P.|url=https://zenodo.org/record/1259369}}</ref>

=== Dubnium ===

[[File:7s electrons dubnium relativistic vs nonrelativistic.svg|thumb|Relativistic (solid line) and nonrelativistic (dashed line) radial distribution of the 7s valence electrons in dubnium.]]
A direct relativistic effect is that as the atomic numbers of elements increase, the innermost electrons begin to revolve faster around the nucleus as a result of an increase of [[electromagnetic attraction]] between an electron and a nucleus. Similar effects have been found for the outermost s [[Atomic orbital|orbitals]] (and p<sub>1/2</sub> ones, though in dubnium they are not occupied): for example, the 7s orbital contracts by 25% in size and is stabilized by 2.6&nbsp;[[electronvolt|eV]].<ref name="Haire" />

A more indirect effect is that the contracted s and p<sub>1/2</sub> orbitals [[shielding effect|shield]] the charge of the nucleus more effectively, leaving less for the outer d and f electrons, which therefore move in larger orbitals. Dubnium is greatly affected by this: unlike the previous group 5 members, its 7s electrons are slightly more difficult to extract than its 6d electrons.<ref name="Haire" />

[[File:Atomic orbitals dubnium.svg|thumb|Relativistic stabilization of the ''n''s orbitals, the destabilization of the {{nobreak|(''n''-1)d}} orbitals and their spin–orbit splitting for the group 5 elements.]]
Another effect is the [[spin–orbit interaction]], particularly spin–orbit splitting, which splits the 6d subshell—the [[azimuthal quantum number]] ℓ of a d&nbsp;shell is 2—into two subshells, with four of the ten orbitals having their ℓ lowered to 3/2 and six raised to 5/2. All ten energy levels are raised; four of them are lower than the other six. (The three 6d electrons normally occupy the lowest energy levels, 6d<sub>3/2</sub>.)<ref name="Haire" />

A single ionized atom of dubnium (Db<sup>+</sup>) should lose a 6d electron compared to a neutral atom; the doubly (Db<sup>2+</sup>) or triply (Db<sup>3+</sup>) ionized atoms of dubnium should eliminate 7s electrons, unlike its lighter homologs. Despite the changes, dubnium is still expected to have five valence electrons; 7p energy levels have not been shown to influence dubnium and its properties. As the 6d orbitals of dubnium are more destabilized than the 5d ones of tantalum, and Db<sup>3+</sup> is expected to have two 6d, rather than 7s, electrons remaining, the resulting +3 oxidation state is expected to be unstable and even rarer than that of tantalum. The ionization potential of dubnium in its maximum +5 oxidation state should be slightly lower than that of tantalum and the ionic radius of dubnium should increase compared to tantalum; this has a significant effect on dubnium's chemistry.<ref name=Haire>{{cite book| title=The Chemistry of the Actinide and Transactinide Elements| editor1-last=Morss|editor1-first=L.R.|editor2-first=N. M.| editor2-last=Edelstein| editor3-last=Fuger|editor3-first=Jean| last1=Hoffman|first1=D. C. |last2=Lee |first2=D. M. |last3=Pershina |first3=V.|chapter=Transactinides and the future elements| publisher= [[Springer Science+Business Media]]| year=2006| isbn=978-1-4020-3555-5| edition=3rd|pages=1652–1752| ref=CITEREFHaire2006}}</ref>

Atoms of dubnium in the solid state should arrange themselves in a [[body-centered cubic]] configuration, like the previous group 5 elements.<ref name="bcc" /> The predicted density of dubnium is 21.6&nbsp;g/cm<sup>3</sup>.<ref name="density" />

== Occurrence ==

There are 160 parts per million of vanadium in the Earth's crust, making it the [[Abundance of elements in Earth's crust|19th most abundant element]]. [[Soil]] contains on average 100 parts per million of vanadium, and [[seawater]] contains 1.5 parts per billion of vanadium. A typical human contains 285 parts per billion of vanadium. Over 60 vanadium ores are known, including [[vanadinite]], [[patronite]], and [[carnotite]].<ref name = "Emsley">{{cite book|last=Emsley|first=John|title=Nature's Building Blocks|year=2011}}</ref> There are 20 parts per million of niobium in the Earth's crust, making it the 33rd most abundant element there. Soil contains on average 24 parts per million of niobium, and seawater contains 900 parts per [[Orders of magnitude (numbers)#1015|quadrillion]] of niobium. A typical human contains 21 parts per billion of niobium. Niobium is in the minerals [[columbite]] and [[pyrochlore]].<ref name = "Emsley"/> There are 2 parts per million of tantalum in the Earth's crust, making it the 51st most abundant element there. Soil contains on average 1 to 2 parts per billion of tantalum, and seawater contains 2 parts per trillion of tantalum. A typical human contains 2.9 parts per billion of tantalum. Tantalum is found in the minerals [[tantalite]] and pyrochlore.<ref name = "Emsley"/> Dubnium does not occur naturally in the Earth's crust, as it has no stable [[Isotope|isotopes]].<ref>{{cite book |last1=Münzenberg |first1=G. |title=Handbook of Nuclear Chemistry |last2=Gupta |first2=M. |publisher=Springer |year=2011 |page=877 |chapter=Production and Identification of Transactinide Elements |doi=10.1007/978-1-4419-0720-2_19}}</ref>

== Production ==

=== Vanadium ===

Vanadium metal is obtained by a multistep process that begins with roasting crushed ore with [[sodium chloride|NaCl]] or [[sodium carbonate|Na<sub>2</sub>CO<sub>3</sub>]] at about 850&nbsp;°C to give [[sodium metavanadate]] (NaVO<sub>3</sub>). An aqueous extract of this solid is acidified to produce "red cake", a polyvanadate salt, which is reduced with [[calcium]] metal. As an alternative for small-scale production, vanadium pentoxide is reduced with [[hydrogen]] or [[magnesium]]. Many other methods are also used, in all of which vanadium is produced as a [[byproduct]] of other processes.<ref name="Moskalyk">{{cite journal|journal= Minerals Engineering|volume= 16|pages= 793–805|doi= 10.1016/S0892-6875(03)00213-9|first= R. R.|last= Moskalyk|author2=Alfantazi, A. M. |title= Processing of vanadium: a review|date= 2003|issue= 9|bibcode= 2003MiEng..16..793M}}</ref> Purification of vanadium is possible by the [[crystal bar process]] developed by [[Anton Eduard van Arkel]] and [[Jan Hendrik de Boer]] in 1925. It involves the formation of the metal iodide, in this example [[vanadium(III) iodide]], and the subsequent decomposition to yield pure metal:<ref>{{cite journal|title= Preparation of High-Purity Vanadium Metals by the Iodide Refining Process|journal= Journal of the Electrochemical Society|volume= 108|page=88|date= 1961|first= O. N.|last= Carlson|author2=Owen, C. V. |doi= 10.1149/1.2428019}}</ref>
:2 V + 3 I<sub>2</sub> {{eqm}} 2 VI<sub>3</sub>

[[File:FerroVanadium.jpg|thumb|Ferrovanadium chunks]]

Most vanadium is used as a component of a [[steel]] alloy called [[ferrovanadium]]. Ferrovanadium is produced directly by reducing a mixture of vanadium oxide, iron oxides and iron in an electric furnace. The vanadium ends up in [[pig iron]] produced from vanadium-bearing magnetite. Depending on the ore used, the slag contains up to 25% of vanadium.<ref name="Moskalyk" />

Approximately 70000 [[tonnes]] of vanadium ore are produced yearly, with 25000 t of vanadium ore being produced in Russia, 24000 in [[South Africa]], 19000 in China, and 1000 in [[Kazakhstan]]. 7000 t of vanadium metal are produced each year. It is impossible to obtain vanadium by heating its ore with carbon. Instead, vanadium is produced by heating [[vanadium oxide]] with calcium in a [[pressure vessel]]. Very high-purity vanadium is produced from a reaction of [[vanadium trichloride]] with magnesium.<ref name = "Emsley"/>

=== Niobium and tantalum ===

{| class="wikitable" style="text-align: right; float: right"
|+ Mine production of niobium (t)<ref name="USGSNiobi">{{cite web |author=Cunningham, Larry D. |url=http://minerals.usgs.gov/minerals/pubs/commodity/niobium/ |title=USGS Minerals Information: Niobium (Columbium) and Tantalum |publisher=Minerals.usgs.gov |date=5 April 2012 |access-date=17 August 2012 |archive-date=28 January 2013 |archive-url=https://web.archive.org/web/20130128101220/http://minerals.usgs.gov/minerals/pubs/commodity/niobium/ |url-status=live }}</ref> (USGS estimate)<ref>{{Cite web|url=https://www.usgs.gov/centers/nmic/niobium-columbium-and-tantalum-statistics-and-information|title=Niobium (Columbium) and Tantalum Statistics and Information &#124; U.S. Geological Survey|access-date=2 December 2021|archive-date=6 March 2019|archive-url=https://web.archive.org/web/20190306043939/https://minerals.usgs.gov/minerals/pubs/commodity/niobium/mcs-2019-tanta.pdf|url-status=live}}</ref>
|-
! scope="col" | Year
! scope="col" | Australia
! scope="col" | Brazil
! scope="col" | Canada
|-
! scope="row" | 2000
| 160
| 30,000
| 2,290
|-
! scope="row" | 2001
| 230
| 22,000
| 3,200
|-
! scope="row" | 2002
| 290
| 26,000
| 3,410
|-
! scope="row" | 2003
| 230
| 29,000
| 3,280
|-
! scope="row" | 2004
| 200
| 29,900
| 3,400
|-
! scope="row" | 2005
| 200
| 35,000
| 3,310
|-
! scope="row" | 2006
| 200
| 40,000
| 4,167
|-
! scope="row" | 2007
| {{Unknown}}
| 57,300
| 3,020
|-
! scope="row" | 2008
| {{Unknown}}
| 58,000
| 4,380
|-
! scope="row" | 2009
| {{Unknown}}
| 58,000
| 4,330
|-
! scope="row" | 2010
| {{Unknown}}
| 58,000
| 4,420
|-
! scope="row" | 2011
| {{Unknown}}
| 58,000
| 4,630
|-
! scope="row" | 2012
| {{Unknown}}
| 63,000
| 5,000
|-
! scope="row" | 2013
| {{Unknown}}
| 53,100
| 5,260
|-
! scope="row" | 2014
| {{Unknown}}
| 53,000
| 5,000
|-
! scope="row" | 2015
| {{Unknown}}
| 58,000
| 5,750
|-
! scope="row" | 2016
| {{Unknown}}
| 57,000
| 6,100
|-
! scope="row" | 2017
| {{Unknown}}
| 60,700
| 6,980
|-
! scope="row" | 2018
| {{Unknown}}
| 59,000
| 7,700
|-
! scope="row" | 2019
| {{Unknown}}
| 88,900
| 6,800
|}

After the separation from the other minerals, the [[mixed oxide]]s of tantalum [[tantalum pentoxide|{{chem2|Ta2O5}}]] and niobium [[Niobium pentoxide|{{chem2|Nb2O5}}]] are obtained. To produce niobium, the first step in the processing is the reaction of the oxides with [[hydrofluoric acid]]:<ref name="ICE" />

:{{chem2|Ta2O5 + 14 HF → 2 H2[TaF7] + 5 H2O}}
:{{chem2|Nb2O5 + 10 HF → 2 H2[NbOF5] + 3 H2O}}

The first industrial scale separation, developed by [[Switzerland|Swiss]] [[chemist]] [[Jean Charles Galissard de Marignac|de Marignac]], exploits the differing [[Solubility|solubilities]] of the complex niobium and tantalum [[fluoride]]s, dipotassium oxypentafluoroniobate monohydrate ({{chem2|K2[NbOF5]*H2O}}) and dipotassium heptafluorotantalate ({{chem2|K2[TaF7]}}) in water. Newer processes use the liquid extraction of the fluorides from [[aqueous]] solution by [[organic solvents]] like [[cyclohexanone]].<ref name="ICE" /> The complex niobium and tantalum fluorides are extracted separately from the [[organic solvent]] with water and either precipitated by the addition of [[potassium fluoride]] to produce a potassium fluoride complex, or precipitated with [[ammonia]] as the pentoxide:<ref name="HollemanAF" />

:{{chem2|H2[NbOF5] + 2 KF → K2[NbOF5]↓ + 2 HF}}

Followed by:
:{{chem2|2 H2[NbOF5] + 10 NH4OH → Nb2O5↓ + 10 NH4F + 7 H2O}}

Several methods are used for the [[Reduction (chemistry)|reduction]] to metallic niobium. The [[electrolysis]] of a [[Molten salt|molten mixture]] of {{chem2|K2}}[{{chem2|NbOF5}}] and [[sodium chloride]] is one; the other is the reduction of the fluoride with [[sodium]]. With this method, a relatively high purity niobium can be obtained. In large scale production, {{chem2|Nb2O5}} is reduced with hydrogen or carbon.<ref name="HollemanAF" /> In the [[aluminothermic reaction]], a mixture of [[iron oxide]] and niobium oxide is reacted with [[aluminium]]:
:{{chem2|3 Nb2O5 + Fe2O3 + 12 Al → 6 Nb + 2 Fe + 6 Al2O3}}

Small amounts of oxidizers like [[sodium nitrate]] are added to enhance the reaction. The result is [[aluminium oxide]] and [[ferroniobium]], an alloy of iron and niobium used in steel production.<ref>{{cite book|title = Progress in Niobium Markets and Technology 1981–2001|author = Tither, Geoffrey|url = https://www.cbmm.com/portug/sources/techlib/science_techno/table_content/images/pdfs/oppening.pdf|journal = Niobium Science & Technology: Proceedings of the International Symposium Niobium 2001 (Orlando, Florida, USA)|date = 2001|isbn = 978-0-9712068-0-9|editor = Minerals, Metals and Materials Society|url-status = dead|archive-url = https://web.archive.org/web/20081217100553/http://www.cbmm.com.br/portug/sources/techlib/science_techno/table_content/images/pdfs/oppening.pdf|archive-date = 17 December 2008|df = dmy-all}}</ref><ref>{{cite book|title=The Production of Ferroniobium at the Niobec mine 1981–2001 |first=Claude |last=Dufresne |author2=Goyette, Ghislain |url=https://www.cbmm.com/portug/sources/techlib/science_techno/table_content/sub_1/images/pdfs/start.pdf |journal=Niobium Science & Technology: Proceedings of the International Symposium Niobium 2001 (Orlando, Florida, USA) |date=2001 |isbn=978-0-9712068-0-9 |editor = Minerals, Metals and Materials Society |url-status=dead |archive-url=https://web.archive.org/web/20081217100559/http://www.cbmm.com.br/portug/sources/techlib/science_techno/table_content/sub_1/images/pdfs/start.pdf |archive-date=17 December 2008 }}</ref> Ferroniobium contains between 60 and 70% niobium.<ref name="tesla">{{cite web|url = http://tesla.desy.de/new_pages/TESLA_Reports/2001/pdf_files/tesla2001-27.pdf|title = Niob für TESLA|access-date = 2 September 2008|first = J.|last = Kouptsidis|author2 = Peters, F.|author3 = Proch, D.|author4 = Singer, W.|publisher = Deutsches Elektronen-Synchrotron DESY|language = de|url-status = dead|archive-url = https://web.archive.org/web/20081217100548/http://tesla.desy.de/new_pages/TESLA_Reports/2001/pdf_files/tesla2001-27.pdf|archive-date = 17 December 2008|df = dmy-all}}</ref> Without iron oxide, the aluminothermic process is used to produce niobium. Further purification is necessary to reach the grade for [[superconductive]] alloys. [[Electron beam melting]] under vacuum is the method used by the two major distributors of niobium.<ref name="Aguly"/><ref name="Chou">{{cite journal|journal = The Iron and Steel Institute of Japan International|volume = 32|date = 1992|issue = 5|doi = 10.2355/isijinternational.32.673|title = Electron Beam Melting and Refining of Metals and Alloys|first = Alok|last = Choudhury|author2=Hengsberger, Eckart |pages = 673–681|doi-access = free}}</ref>

{{as of|2013}}, [[Companhia Brasileira de Metalurgia e Mineração|CBMM]] from Brazil controlled 85 percent of the world's niobium production.<ref name="lucchesi2013">{{Citation
 |last1=Lucchesi |first1=Cristane |last2=Cuadros|first2=Alex |date=April 2013 |title=Mineral Wealth |type=paper |magazine=[[Bloomberg Markets]] |page=14}}</ref> The [[United States Geological Survey]] estimates that the production increased from 38,700 tonnes in 2005 to 44,500{{Nbsp}}tonnes in 2006.<ref name="USGSCS2006">{{cite web |url=http://minerals.usgs.gov/minerals/pubs/commodity/niobium/colummcs06.pdf |title=Niobium (Columbium) |first=John F. |last=Papp |publisher=USGS 2006 Commodity Summary |access-date=20 November 2008 |archive-date=17 December 2008 |archive-url=https://web.archive.org/web/20081217100548/http://minerals.usgs.gov/minerals/pubs/commodity/niobium/colummcs06.pdf |url-status=live }}</ref><ref name="USGSCS2007">{{cite web |url=http://minerals.usgs.gov/minerals/pubs/commodity/niobium/colummcs07.pdf |title=Niobium (Columbium) |first=John F. |last=Papp |publisher=USGS 2007 Commodity Summary |access-date=20 November 2008 |archive-date=5 August 2017 |archive-url=https://web.archive.org/web/20170805170910/https://minerals.usgs.gov/minerals/pubs/commodity/niobium/colummcs07.pdf |url-status=live }}</ref> Worldwide resources are estimated to be 4.4 million tonnes.<ref name="USGSCS2007" /> During the ten-year period between 1995 and 2005, the production more than doubled, starting from 17,800 tonnes in 1995.<ref name="USGSCS1997">{{cite web|url = http://minerals.usgs.gov/minerals/pubs/commodity/niobium/230397.pdf|title = Niobium (Columbium)|first = John F.|last = Papp|publisher = USGS 1997 Commodity Summary|access-date = 20 November 2008|archive-date = 11 January 2019|archive-url = https://web.archive.org/web/20190111003407/https://minerals.usgs.gov/minerals/pubs/commodity/niobium/230397.pdf|url-status = live}}</ref> Between 2009 and 2011, production was stable at 63,000{{Nbsp}}tonnes per year,<ref>[http://minerals.usgs.gov/minerals/pubs/commodity/niobium/mcs-2011-niobi.pdf Niobium (Colombium)] {{Webarchive|url=https://web.archive.org/web/20120708152542/http://minerals.usgs.gov/minerals/pubs/commodity/niobium/mcs-2011-niobi.pdf |date=8 July 2012 }} U.S. Geological Survey, Mineral Commodity Summaries, January 2011</ref> with a slight decrease in 2012 to only 50,000{{Nbsp}}tonnes per year.<ref>[http://minerals.usgs.gov/minerals/pubs/commodity/niobium/mcs-2016-niobi.pdf Niobium (Colombium)] {{Webarchive|url=https://web.archive.org/web/20160306095041/http://minerals.usgs.gov/minerals/pubs/commodity/niobium/mcs-2016-niobi.pdf |date=6 March 2016 }} U.S. Geological Survey, Mineral Commodity Summaries, January 2016</ref>

70,000{{Nbsp}}tonnes of tantalum ore are produced yearly. Brazil produces 90% of tantalum ore, with Canada, Australia, China, and [[Rwanda]] also producing the element. The demand for tantalum is around 1,200{{Nbsp}}tonnes per year.<ref name="Emsley" />

=== Dubnium and beyond ===
Dubnium is produced synthetically by bombarding [[actinides]] with lighter elements.<ref name = "Emsley"/> To date, no experiments in a [[Particle accelerator|supercollider]] have been conducted to [[synthetic element|synthesize]] the next member of the group, either unpentseptium (Ups) or unpentennium (Upe). As unpentseptium and unpentennium are both late [[period 8 element]]s, it is unlikely that these elements will be synthesized in the near future; current attempts have only been made on elements up to atomic number 127.<ref name="emsley">{{cite book |last=Emsley |first=John |title=Nature's Building Blocks: An A-Z Guide to the Elements |publisher=Oxford University Press |year=2011 |isbn=978-0-19-960563-7 |edition=New |location=New York, NY |page=588}}</ref>

== Applications ==

[[File:Sink and taps in the men's locker room 3 BW.jpg|thumb|right|Niobium is often a minor component in stainless steel.]]

Vanadium's main application is in alloys, such as [[vanadium steel]]. Vanadium alloys are used in [[spring (device)|springs]], [[tools]], [[jet engines]], [[armor]] plating, and [[nuclear reactors]]. [[Vanadium oxide]] gives ceramics a golden color, and other vanadium compounds are used as [[catalysts]] to produce [[polymers]].<ref name = "Emsley"/>

Small amounts of niobium are added to [[stainless steel]] to improve its quality. Niobium alloys are also used in rocket nozzles because of niobium's high [[corrosion]] resistance.<ref name = "Emsley"/>

Tantalum has four main types of applications. Tantalum is added into objects exposed to high temperatures, in [[electronic devices]], in [[surgical implant]]s, and for handling corrosive substances.<ref name = "Emsley"/>

Dubnium has no applications due to the difficulty of its synthesis and the very short half-lives of even its longest-lived isotopes.<ref name="Karpov graph">{{Cite book |last1=Karpov |first1=A. V. |title=Exciting Interdisciplinary Physics |last2=Zagrebaev |first2=V. I. |last3=Palenzuela |first3=Y. M. |last4=Greiner |first4=W. |date=2013 |publisher=Springer International Publishing |isbn=978-3-319-00046-6 |editor-last=Greiner |editor-first=W. |series=FIAS Interdisciplinary Science Series |pages=69–79 |language=en |article=Superheavy Nuclei: Decay and Stability |doi=10.1007/978-3-319-00047-3_6}}</ref>

== Biological occurrences ==

{{main|Vanadium#Biological role}}
Out of the group 5 elements, only vanadium has been identified as playing a role in the biological chemistry of living systems, but even it plays a very limited role in [[biology]], and is more important in ocean environments than on land.<ref name=":0" />
[[File:Bluebell_tunicates_Nick_Hobgood.jpg|thumb|right|[[Tunicate|Tunicates]] such as this bluebell tunicate contain vanadium as [[vanabins]].]]
Vanadium, essential to [[ascidiacea|ascidians]] and [[tunicate]]s as [[vanabins]], has been known in the [[blood cell]]s of [[Ascidiacea]] (sea squirts) since 1911,<ref name="henze1911">{{cite journal|last1=Henze|first1=M.|title=Untersuchungen über das Blut der Ascidien. I. Mitteilung. Die Vanadiumverbindung der Blutkörperchen|journal=Hoppe-Seyler's Zeitschrift für Physiologische Chemie|date=1911|volume=72|issue=5–6|pages=494–501|doi=10.1515/bchm2.1911.72.5-6.494|language=de|url=https://zenodo.org/record/1448780}}</ref><ref name="michibata2002">{{cite journal | doi = 10.1002/jemt.10042 | last1 = Michibata | first1 = H | last2 = Uyama | first2 = T | last3 = Ueki | first3 = T | last4 = Kanamori | first4 = K | name-list-style = vanc | year = 2002 | title = Vanadocytes, cells hold the key to resolving the highly selective accumulation and reduction of vanadium in ascidians | url = http://ir.lib.hiroshima-u.ac.jp/files/public/0/22/20141016115442843522/MicroscopResTech_56_421-434_2002.pdf | journal = Microscopy Research and Technique | volume = 56 | issue = 6 | pages = 421–434 | pmid = 11921344 | s2cid = 15127292 | access-date = 26 June 2019 | archive-date = 17 March 2020 | archive-url = https://web.archive.org/web/20200317132408/https://ir.lib.hiroshima-u.ac.jp/files/public/0/22/20141016115442843522/MicroscopResTech_56_421-434_2002.pdf | url-status = dead }}</ref> in concentrations of vanadium in their blood more than 100 times higher than the concentration of vanadium in the seawater around them. Several species of macrofungi accumulate vanadium (up to 500&nbsp;mg/kg in dry weight).<ref>{{cite journal|last1=Kneifel|first1=Helmut |last2=Bayer|first2=Ernst |year=1997|title=Determination of the Structure of the Vanadium Compound, Amavadine, from Fly Agaric|journal=Angewandte Chemie International Edition in English|volume=12|issue=6|pages=508|issn=1521-3773|doi=10.1002/anie.197305081}}</ref> Vanadium-dependent [[bromoperoxidase]] generates organobromine compounds in a number of species of marine [[algae]].<ref>{{Cite journal|journal = Natural Product Reports|year = 2004|volume = 21|issue = 1|pmid = 15039842|doi = 10.1039/b302337k|title = The role of vanadium bromoperoxidase in the biosynthesis of halogenated marine natural products|first1 = Alison|last1 = Butler|last2= Carter-Franklin|first2=Jayme N.|pages = 180–8}}</ref>

[[Rat]]s and [[chicken]]s are also known to require vanadium in very small amounts and deficiencies result in reduced growth and impaired [[reproduction]].<ref>{{cite journal|title = Growth Effects of Vanadium in the Rat|first1 = Klaus|last1 = Schwarz|last2=Milne|first2=David B.|journal = Science|volume = 174|issue = 4007|year = 1971|pages = 426–428|jstor = 1731776|doi = 10.1126/science.174.4007.426|pmid = 5112000|bibcode = 1971Sci...174..426S | s2cid=24362265 }}</ref> Vanadium is a relatively controversial [[dietary supplement]], primarily for increasing [[insulin]] sensitivity<ref>{{cite journal|journal = Diabetes Care|volume = 26|pages = 1277–1294|year = 2003|title = Systematic Review of Herbs and Dietary Supplements for Glycemic Control in Diabetes|first1 = Gloria Y.|last1 = Yeh|last2= Eisenberg|first2=David M.|last3=Kaptchuk|first3=Ted J.|last4=Phillips|first4=Russell S.|url = http://care.diabetesjournals.org/cgi/content/full/26/4/1277|doi = 10.2337/diacare.26.4.1277|pmid = 12663610|issue = 4|doi-access = free|url-access = subscription}}</ref> and [[body-building]]. [[Vanadyl sulfate]] may improve glucose control in people with [[type 2 diabetes]].<ref name="Badmaev">{{cite journal| journal = The Journal of Alternative and Complementary Medicine| volume = 5| year = 1999| pages = 273–291| title = Vanadium: a review of its potential role in the fight against diabetes| last1 = Badmaev| first1 = V.| doi = 10.1089/acm.1999.5.273| last2 = Prakash| first2 = Subbalakshmi| last3 = Majeed| first3 = Muhammed| pmid=10381252| issue = 3}}</ref> In addition, decavanadate and oxovanadates are species that potentially have many biological activities and that have been successfully used as tools in the comprehension of several biochemical processes.<ref>{{cite journal|journal = Journal of Inorganic Biochemistry| volume = 103|pages = 536–546|year = 2009|title = Decavanadate and oxovanadates: Oxometalates with many biological activities|first1 = Manuel|last1 = Aureliano| last2=Crans|first2=Debbie C.| issue = 4| doi = 10.1016/j.jinorgbio.2008.11.010| pmid = 19110314}}</ref>

== Toxicity and precautions ==

Pure vanadium is not known to be toxic. However, [[vanadium pentoxide]] causes severe irritation of the eyes, nose, and throat.<ref name = "Emsley"/> Tetravalent [[vanadyl sulfate|VOSO<sub>4</sub>]] has been reported to be at least 5 times more toxic than trivalent V<sub>2</sub>O<sub>3</sub>.<ref>{{cite journal|last= Roschin|first= A. V.|date= 1967|title= Toxicology of vanadium compounds used in modern industry|journal= Gig Sanit. (Water Res.)|volume= 32|issue= 6|pages= 26–32|pmid= 5605589}}</ref> The [[Occupational Safety and Health Administration]] has set an exposure limit of 0.05&nbsp;mg/m<sup>3</sup> for vanadium pentoxide dust and 0.1&nbsp;mg/m<sup>3</sup> for vanadium pentoxide fumes in workplace air for an 8-hour workday, 40-hour work week.<ref name="OSHA">{{cite web|url= http://www.osha.gov/SLTC/healthguidelines/vanadiumpentoxidedust/recognition.html|title= Occupational Safety and Health Guidelines for Vanadium Pentoxide|publisher= Occupational Safety and Health Administration|access-date= 29 January 2009|url-status= dead|archive-url= https://web.archive.org/web/20090106063227/http://www.osha.gov/SLTC/healthguidelines/vanadiumpentoxidedust/recognition.html|archive-date= 6 January 2009}}</ref> The [[National Institute for Occupational Safety and Health]] has recommended that 35&nbsp;mg/m<sup>3</sup> of vanadium be considered immediately dangerous to life and health, that is, likely to cause permanent health problems or death.<ref name="OSHA" /> Vanadium compounds are poorly absorbed through the gastrointestinal system. Inhalation of vanadium and vanadium compounds results primarily in adverse effects on the respiratory system.<ref>{{cite book|last= Sax|first= N. I.|date= 1984|title= Dangerous Properties of Industrial Materials|edition= 6th|publisher= Van Nostrand Reinhold Company|pages= 2717–2720}}</ref><ref name="ress" /><ref>{{cite journal|title= Nanoparticulate Vanadium Oxide Potentiated Vanadium Toxicity in Human Lung Cells|author= Wörle-Knirsch, Jörg M. |author2= Kern, Katrin |author3= Schleh, Carsten |author4= Adelhelm, Christel |author5= Feldmann, Claus |author6= Krug, Harald F. |name-list-style= amp|journal= Environ. Sci. Technol. |date= 2007|volume= 41|pages= 331–336|doi= 10.1021/es061140x|pmid= 17265967|issue= 1|bibcode= 2007EnST...41..331W}}</ref> Quantitative data are, however, insufficient to derive a subchronic or chronic inhalation reference dose. Other effects have been reported after oral or inhalation exposures on blood parameters,<ref>{{cite journal |last=Ścibior |first=A. |author2=Zaporowska, H. |author3=Ostrowski, J. |date=2006 |title=Selected haematological and biochemical parameters of blood in rats after subchronic administration of vanadium and/or magnesium in drinking water |journal=Archives of Environmental Contamination and Toxicology |volume=51 |issue=2 |pages=287–295 |doi=10.1007/s00244-005-0126-4 |pmid=16783625|bibcode=2006ArECT..51..287S |s2cid=43805930 }}</ref><ref>{{cite journal |last=Gonzalez-Villalva |first=A. |display-authors=etal |date= 2006|title=Thrombocytosis induced in mice after subacute and subchronic V2O5 inhalation |journal=Toxicology and Industrial Health |volume=22 |issue=3 |pages=113–116 |doi=10.1191/0748233706th250oa |pmid=16716040|bibcode=2006ToxIH..22..113G |s2cid=9986509 }}</ref> liver,<ref>{{cite journal|journal= Toxicology|volume= 228|date= 2006|pages= 162–170|doi= 10.1016/j.tox.2006.08.022|title= Pentavalent vanadium induces hepatic metallothionein through interleukin-6-dependent and -independent mechanisms|author= Kobayashi, Kazuo|pmid= 16987576|issue= 2–3|last2= Himeno|first2= Seiichiro|last3= Satoh|first3= Masahiko|last4= Kuroda|first4= Junji|last5= Shibata|first5= Nobuo|last6= Seko|first6= Yoshiyuki|last7= Hasegawa|first7= Tatsuya|bibcode= 2006Toxgy.228..162K}}</ref> neurological development,<ref>{{cite journal |last=Soazo |first=Marina |author2=Garcia, Graciela Beatriz |date=2007 |title=Vanadium exposure through lactation produces behavioral alterations and CNS myelin deficit in neonatal rats |journal=Neurotoxicology and Teratology |volume=29 |issue=4 |pages=503–510 |doi=10.1016/j.ntt.2007.03.001 |pmid=17493788|bibcode=2007NTxT...29..503S }}</ref> and other organs<ref>{{cite journal|last= Barceloux|first= Donald G.|author2=Barceloux, Donald |date= 1999|title= Vanadium|journal= Clinical Toxicology|volume= 37|issue= 2|pages= 265–278|doi= 10.1081/CLT-100102425|pmid= 10382561}}</ref> in rats.

There is little evidence that vanadium or vanadium compounds are reproductive toxins or [[teratogen]]s. Vanadium pentoxide was reported to be carcinogenic in male rats and in male and female mice by inhalation in an NTP study,<ref name="ress">{{cite journal |last=Ress |first=N. B. |display-authors=etal |date=2003 |title=Carcinogenicity of inhaled vanadium pentoxide in F344/N rats and B6C3F1 mice |journal=Toxicological Sciences |volume=74 |issue=2 |pages=287–296 |doi=10.1093/toxsci/kfg136 |pmid=12773761|doi-access=free }}</ref> although the interpretation of the results has recently been disputed.<ref>{{cite journal |last=Duffus |first=J. H. |date=2007 |title=Carcinogenicity classification of vanadium pentoxide and inorganic vanadium compounds, the NTP study of carcinogenicity of inhaled vanadium pentoxide, and vanadium chemistry |journal=[[Regulatory Toxicology and Pharmacology]] |volume=47 |issue=1 |pages=110–114 |doi=10.1016/j.yrtph.2006.08.006 |pmid=17030368}}</ref> The carcinogenicity of vanadium has not been determined by the [[United States Environmental Protection Agency]].<ref>{{cite web|url= https://rais.ornl.gov/tox/profiles/vanadium_f_V1.html|title= Toxicity Summary for Vanadium|date= 1991|first= Dennis M.|last= Opreskos |access-date=8 November 2008 |publisher= Oak Ridge National Laboratory}}</ref> Vanadium traces in [[diesel fuel]]s are the main fuel component in [[high temperature corrosion]]. During combustion, vanadium oxidizes and reacts with sodium and sulfur, yielding [[vanadate]] compounds with melting points as low as 530&nbsp;°C, which attack the [[passivation (chemistry)|passivation layer]] on steel and render it susceptible to corrosion. The solid vanadium compounds also abrade engine components.<ref>{{cite book |page= 92 |url= https://books.google.com/books?id=RC_k4q6y-JIC&pg=PA92 |title= Pounder's Marine Diesel Engines and Gas Turbines |isbn= 9780080943619 |last1= Woodyard |first1= Doug |date= 2009-08-18| publisher=Butterworth-Heinemann }}</ref><ref>{{cite book |page= 152 |url= https://books.google.com/books?id=J_AkNu-Y1wQC&pg=PA152 |title= Fuels and Lubricants Handbook: Technology, Properties, Performance, and Testing |isbn= 9780803120969 |last1= Totten |first1= George E. |last2= Westbrook |first2= Steven R. |last3= Shah |first3= Rajesh J. |date= 2003-06-01}}</ref>

Niobium has no known biological role. While niobium dust is an eye and skin irritant<ref name = "Emsley"/> and a potential fire hazard, elemental niobium on a larger scale is physiologically inert (and thus hypoallergenic) and harmless. It is often used in jewelry and has been tested for use in some medical implants.<ref>{{cite journal|title = New trends in the use of metals in jewellery|author=Vilaplana, J.|author2=Romaguera, C.|author3=Grimalt, F.|author4=Cornellana, F.|journal = Contact Dermatitis|volume = 25|issue = 3 |pages = 145–148|date = 1990|doi = 10.1111/j.1600-0536.1991.tb01819.x|pmid = 1782765|s2cid=30201028|doi-access = }}</ref><ref>{{cite journal|title = New developments in jewellery and dental materials|first = J.|last = Vilaplana|author2=Romaguera, C. | journal = Contact Dermatitis|volume = 39|issue = 2| pages = 55–57|date = 1998|doi = 10.1111/j.1600-0536.1998.tb05832.x|pmid = 9746182|s2cid = 34271011}}</ref> Niobium and its compounds thought to be slightly toxic. Short- and long-term exposure to niobates and niobium chloride, two water-soluble chemicals, have been tested in rats. Rats treated with a single injection of niobium pentachloride or niobates show a [[median lethal dose]] (LD{{sub|50}}) between 10 and 100&nbsp;mg/kg.<ref name="Haley">{{cite journal|title = Pharmacology and toxicology of niobium chloride|author=Haley, Thomas J.|author2=Komesu, N.|author3=Raymond, K.|journal = [[Toxicology and Applied Pharmacology]]|volume = 4|issue = 3|pages = 385–392|date = 1962|doi = 10.1016/0041-008X(62)90048-0|pmid=13903824|bibcode=1962ToxAP...4..385H }}</ref><ref>{{cite journal|title = The Toxicity of Niobium Salts |author=Downs, William L. |display-authors=4 |author2=Scott, James K. |author3=Yuile, Charles L. |author4=Caruso, Frank S. |author5=Wong, Lawrence C. K.|journal = American Industrial Hygiene Association Journal|volume = 26|issue = 4|pages = 337–346|date = 1965|doi = 10.1080/00028896509342740|pmid = 5854670}}</ref><ref>{{cite journal|title = Zirconium, Niobium, Antimony, Vanadium and Lead in Rats: Life term studies|author=Schroeder, Henry A.|author2=Mitchener, Marian|author3=Nason, Alexis P.|journal = Journal of Nutrition|volume = 100|issue = 1|pages = 59–68|date=1970|pmid =5412131|doi=10.1093/jn/100.1.59|s2cid=4444415|url = https://pdfs.semanticscholar.org/7730/157588b8312d9076f95fcfb78d404a893033.pdf|archive-url = https://web.archive.org/web/20200219052439/https://pdfs.semanticscholar.org/7730/157588b8312d9076f95fcfb78d404a893033.pdf|url-status = dead|archive-date = 2020-02-19}}</ref> For oral administration the toxicity is lower; a study with rats yielded a LD{{sub|50}} after seven days of 940&nbsp;mg/kg.<ref name="Haley" />

Compounds containing tantalum are rarely encountered in the laboratory, and it and its compounds rarely cause injury, and when they do, the injuries are normally rashes.<ref name = "Emsley"/> The metal is highly [[biocompatible]]<ref name="Gerald L. Burke 1940">{{cite journal|journal = Canadian Medical Association Journal |first = Gerald L. |last = Burke |date = 1940 |title =The Corrosion of Metals in Tissues; and An Introduction to Tantalum |volume = 43|issue = 2 |pages = 125–128 |pmid = 20321780 |pmc = 538079 }}</ref> and is used for body [[implant (medicine)|implants]] and [[coating]]s, therefore attention may be focused on other elements or the physical nature of the [[chemical compound]].<ref>{{cite journal|journal = Biomaterials|author = Matsuno H|author2 = Yokoyama A|author3 = Watari F|author4 = Uo M|author5 = Kawasaki T.|date = 2001|volume = 22|title = Biocompatibility and osteogenesis of refractory metal implants, titanium, hafnium, niobium, tantalum and rhenium. Biocompatibility of tantalum.|doi = 10.1016/S0142-9612(00)00275-1|pmid=11336297|issue = 11|pages = 1253–62}}</ref> People can be exposed to tantalum in the workplace by breathing it in, skin contact, or eye contact. The [[Occupational Safety and Health Administration]] (OSHA) has set the legal limit ([[permissible exposure limit]]) for tantalum exposure in the workplace as 5&nbsp;mg/m<sup>3</sup> over an 8-hour workday. The [[National Institute for Occupational Safety and Health]] (NIOSH) has set a [[recommended exposure limit]] of 5&nbsp;mg/m<sup>3</sup> over an 8-hour workday and a short-term limit of 10&nbsp;mg/m<sup>3</sup>. At levels of 2500&nbsp;mg/m<sup>3</sup>, tantalum is [[IDLH|immediately dangerous to life and health]].<ref>{{Cite web|title = CDC – NIOSH Pocket Guide to Chemical Hazards – Tantalum (metal and oxide dust, as Ta)|url = https://www.cdc.gov/niosh/npg/npgd0585.html|website = www.cdc.gov|access-date = 2015-11-24}}</ref>

== Notes ==
{{notelist}}

== References ==

{{reflist}}

== Further reading ==

*{{cite journal | doi =10.1016/S0920-5861(02)00318-8 | title =Vanadium to dubnium: from confusion through clarity to complexity | year =2003 | last1 =Greenwood | first1 =N | journal =Catalysis Today | volume =78 | issue =1–4 | pages =5–11}}

{{Periodic table (navbox)}}
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{{Group 5 elements}}

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[[Category:Groups (periodic table)]]