Vanadium

23 titanium ← vanadium → chromium - ↑ V ↓ Nb periodic table
General
Name, Symbol, Number	vanadium, V, 23
Chemical series	transition metals
Group, Period, Block	5, 4, d
Appearance	silver-grey metal
Atomic mass	50.9415(1) g/mol
Electron configuration	[Ar] 3d3 4s2
Electrons per shell	2, 8, 11, 2
Physical properties
Phase	solid
Density (near r.t.)	6.0 g/cm³
Liquid density at m.p.	5.5 g/cm³
Melting point	2183 K (1910 °C, 3470 °F)
Boiling point	3680 K (3407 °C, 6165 °F)
Heat of fusion	21.5 kJ/mol
Heat of vaporization	459 kJ/mol
Heat capacity	(25 °C) 24.89 J/(mol·K)
Vapor pressure P/Pa 1 10 100 1 k 10 k 100 k at T/K 2101 2289 2523 2814 3187 3679
Atomic properties
Crystal structure	cubic body centered
Oxidation states	2, 3, 4, 5 (amphoteric oxide)
Electronegativity	1.63 (Pauling scale)
Ionization energies (more)	1st: 650.9 kJ/mol
	2nd: 1414 kJ/mol
	3rd: 2830 kJ/mol
Atomic radius	135 pm
Atomic radius (calc.)	171 pm
Covalent radius	125 pm
Miscellaneous
Magnetic ordering	???
Electrical resistivity	(20 °C) 197 nΩ·m
Thermal conductivity	(300 K) 30.7 W/(m·K)
Thermal expansion	(25 °C) 8.4 µm/(m·K)
Speed of sound (thin rod)	(20 °C) 4560 m/s
Speed of sound (thin rod)	(r.t.) 128 m/s
Shear modulus	47 GPa
Bulk modulus	160 GPa
Poisson ratio	0.37
Mohs hardness	7.0
Vickers hardness	628 MPa
Brinell hardness	628 MPa
CAS registry number	7440-62-2
Notable isotopes
Main article: [[Isotopes of {{{isotopesof}}}]] iso NA half-life DM DE (MeV) DP 48V syn 15.9735 d ε+β+ 4.0123 48Ti 49V syn 330 d ε 0.6019 49Ti 50V 0.25% 1.5×1017y ε 2.2083 50Ti β- 1.0369 50Cr 51V 99.75% V is stable with 28 neutrons

Vanadium (IPA: /vəˈneɪdiəm/) is a chemical element in the periodic table that has the symbol V and atomic number 23. A rare, soft and ductile element, vanadium is found combined in certain minerals and is used mainly to produce certain alloys. It is one of the 26 elements commonly found in living things.

Occurrence

Vanadium is never found as a free element in nature, but it occurs in about 65 different minerals. Among them are patronite (VS₄), vanadinite (Pb₅(VO₄)₃Cl), and carnotite (K₂(UO₂)₂(VO₄)₂.3H₂O). It is also present in bauxite and carbon-containing deposits such as crude oil, coal, oil shale, and tar sands. It has also been detected spectroscopically in light from the Sun and some other stars.

Much of the vanadium metal being produced is now made by calcium reduction of vanadium(V) oxide (V₂O₅) in a pressure vessel. Vanadium is usually recovered as a byproduct or co-product, and for that reason, world resources of the element are not really indicative of available supply.

History

Vanadium was originally discovered by Andrés Manuel del Río, a Spanish mineralogist in Mexico City, in 1803. Using a mineral called "brown lead" (now named vanadinite), he prepared several salts. Their colors reminded him of chromium salts, so he named the element "panchromium." He later renamed it "erythronium" (meaning "red") because most of the salts turned red when heated. French chemist Hippolyte Victor Collet-Descotils incorrectly declared that del Rio's new element was only impure chromium. Del Rio thought himself to be mistaken and accepted the French chemist's statement, which was backed by Del Rio's friend, Baron Alexander von Humboldt.

In 1831, Nils Gabriel Sefström of Sweden rediscovered vanadium in a new oxide he found while working with some iron ores. Later that same year, Friedrich Wöhler confirmed del Rio's earlier work. Later, George William Featherstonhaugh, one of the first U.S. geologists, suggested the element be named "rionium" after Del Rio, but that never happened.

Metallic vanadium was isolated by Henry Enfield Roscoe in 1867, by reducing vanadium(III) chloride (VCl₃) with hydrogen. The name vanadium comes from Vanadis, a goddess in Scandinavian mythology, because the element has beautiful, multicolored chemical compounds.

Notable characteristics

Vanadium is a transition metal in period 4 of the periodic table, situated between titanium and chromium. It is also at the top of group 5 (former group 5B), above niobium and tantalum.

a soft and ductile, silver-grey metal. It has good resistance to corrosion by alkalis, sulfuric and hydrochloric acid. It oxidizes readily at about 933 K. Vanadium has good structural strength and a low fission neutron cross section, making it useful in nuclear applications. Although a metal, it shares with chromium and manganese the property of having valency oxides with acid properties.

Common oxidation states of vanadium include +2, +3, +4 and +5. A popular experiment with ammonium vanadate NH₄VO₃, reducing the compound with zinc metal, can demonstrate colorimetrically all four of these vanadium oxidation states. A +1 oxidation state is rarely seen.

Applications

Approximately 80% of vanadium produced is used as ferrovanadium or as a steel additive. Other uses:

• In such alloys as:
  • specialty stainless steel, e.g. for use in surgical instruments and tools.
  • rust resistant and high speed tool steels.
  • mixed with aluminium in titanium alloys used in jet engines and high-speed airframes
• Vanadium steel alloys are used in axles, crankshafts, gears, and other critical components.
• It is an important carbide stabilizer in making steels.
• Because of its low fission neutron cross section, vanadium has nuclear applications.
• Vanadium foil is used in cladding titanium to steel.
• Vanadium-gallium tape is used in superconducting magnets (175,000 gauss).
• Vanadium pentoxide V₂O₅ is used as a catalyst in manufacturing sulfuric acid (via the contact process) and maleic anhydride. It is also used in making ceramics.
• Glass coated with vanadium dioxide VO₂ can block infrared radiation (and not visible light) at a specific temperature.
• Electrical fuel cells and storage batteries such as vanadium redox batteries.
• Added to corundum to make simulated Alexandrite jewelry.
• Vanadate electrochemical conversion coatings for protecting steel against rust and corrosion

Biological role

In biology, a vanadium atom is an essential component of some enzymes, particularly the vanadium nitrogenase used by some nitrogen-fixing micro-organisms. Vanadium is essential to ascidians or sea squirts in vanadium chromagen proteins. The concentration of vanadium in their blood is more than 100 times higher than the concentration of vanadium in the seawater around them. Rats and chickens are also known to require vanadium in very small amounts and deficiencies result in reduced growth and impaired reproduction.

Administration of oxovanadium compounds has been shown to alleviate diabetes mellitus symptoms in certain animal models and humans. Much like the chromium effect on sugar metabolism, the mechanism of this effect is unknown.

Mineral supplement in drinking water

Vanadium pentoxide V₂O₅ is marketed in Japan as a good mineral health supplement naturally occurring in drinking water. The source of this drinking water is mainly the slopes of Mount Fuji. The water's vanadium pentoxide content ranges from about 80 to 130 μg/liter. It is marketed as being effective against diabetes, eczema, and obesity. There is no mention of its toxicity in the marketing of these products.

Isolation

Vanadium is available commercially and production of a sample in the laboratory is not normally required. Commercially, routes leading to metallic vanadium as main product are not usually required as enough is produced as byproduct in other processes.

In industry, heating of vanadium ore or residues from other processes with salt NaCl or sodium carbonate Na₂CO₃ at about 850°C gives sodium vanadate NaVO₃. This is dissolved in water and acidified to give a red solid which in turn is melted to form a crude form of vanadium pentoxide V₂O₅. Reduction of vanadium pentoxide with calcium gives pure vanadium. An alternative suitable for small scales is the reduction of vanadium pentachloride VCl₅ with hydrogen or magnesium. Many other methods are also in use.

Industrially, most vanadium is used as an additive to improve steels. Rather than proceed via pure vanadium metal it is often sufficient to react the crude of vanadium pentoxide V₂O₅ with crude iron. This produces ferrovanadium suitable for further work.

Compounds

• Vanadium(V) oxide or vanadium pentoxide (V₂O₅): It is used as a catalyst principally in the production of sulfuric acid. It is the source of vanadium used in the manufacture of ferrovanadium. It can be used as a dye and color-fixer.

• Vanadyl sulfate or vanadium(IV) sulfate oxide hydrate (VOSO₄): It is used as a relatively controversial dietary supplement, primarily for increasing insulin levels and body-building. Whether it works for the latter purpose has not been proven, and there is some evidence that athletes who take it are merely experiencing a placebo effect.

• Vanadium(IV) chloride (VCl₄): It is a soluble form of vanadium that is commonly used in the laboratory. V(IV) is the reduced form of V(V), and commonly occurs after anaerobic respiration by dissimilatory, metal-reducing bacteria. VCl₄ reacts violently with water.

Toxicity of vanadium compounds

The toxicity of vanadium depends on its physico-chemical state; particularly on its valence state and solubility. Pentavalent VOSO₄ has been reported to be more than 5 times as toxic as trivalent V₂O₃ (Roschin, 1967). Vanadium compounds are poorly absorbed through the gastrointestinal system. Inhalation exposures to vanadium and vanadium compounds result primarily in adverse effects to the respiratory system (Sax, 1984; ATSDR, 1990). Quantitative data are, however, insufficient to derive a subchronic or chronic inhalation.

There is little evidence that vanadium or vanadium compounds are reproductive toxins or teratogens. There is also no evidence that any vanadium compound is carcinogenic; however, very few adequate studies are available for evaluation. Vanadium has not been classified as to carcinogenicity by the U.S. EPA (1991a).

Isotopes

Naturally occurring vanadium is composed of one stable isotope ⁵¹V and one radioactive isotope ⁵⁰V with a half-life of 1.5×10¹⁷ years. 24 artificial radioisotopes have been characterized (in the range of mass number between 40 and 65) with the most stable being ⁴⁹V with a half-life of 330 days, and ⁴⁸V with a half-life of 15.9735 days. All of the remaining radioactive isotopes have half-lives shorter than an hour, the majority of them below 10 seconds. In 4 isotopes, metastable excited states were found (including 2 metastable states for ⁶⁰V).

The primary decay mode before the most abundant stable isotope ⁵¹V is electron capture. The next most common mode is beta decay. The primary decay products before ⁵¹V are element 22 (titanium) isotopes and the primary products after are element 24 (chromium) isotopes.

Precautions

Powdered metallic vanadium is a fire hazard, and unless known otherwise, all vanadium compounds should be considered highly toxic. Generally, the higher the oxidation state of vanadium, the more toxic the compound is. The most dangerous one is vanadium pentoxide.

The Occupational Safety and Health Administration (OSHA) has set an exposure limit of 0.05 mg/m³ for vanadium pentoxide dust and 0.1 mg/m³ for vanadium pentoxide fumes in workplace air for an 8-hour workday, 40-hour work week.

The National Institute for Occupational Safety and Health (NIOSH) has recommended that 35 mg/m³ of vanadium be considered immediately dangerous to life and health. This is the exposure level of a chemical that is likely to cause permanent health problems or death.

See also

• Chemical element
• Metal
• Transition element

References

ISBN links support NWE through referral fees

• Los Alamos National Laboratory – Vanadium

External links

• WebElements.com – Vanadium
• Mineral Information Institute – Vanadium
• ATSDR – ToxFAQs: Vanadium
• The Vanadium Redox Battery was invented at The University of New South Wales

Credits

New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:

• Vanadium  ^history

The history of this article since it was imported to New World Encyclopedia:

• History of "Vanadium"

Note: Some restrictions may apply to use of individual images which are separately licensed.