Vanadium

Atomic Number:

23

Melting Point: 1910 ºC
Atomic Symbol: V Boiling Point:  3407 ºC
Atomic Weight: 50.9414 amu Density: 6110 kg/m 3
Atomic Radius:

132.1 pm

Oxidation States: 5, 4, 3, 2
Covalent Radius: 125 pm Electron Configuration: [Ar]4s23d3
van der Waals Radius:

--

State of Matter: solid 

History

(Scandinavian goddess, Vanadis) Vanadium was first discovered by del Rio in 1801. Unfortunately, a French chemist incorrectly declared that del Rio's new element was only impure chromium. Del Rio thought himself to be mistaken and accepted the French chemists' statement.

The element was rediscovered in 1830 by Sefstrom, who named the element in honor of the Scandinavian goddess, Vanadis, because of its beautiful multicolored compounds. It was isolated in nearly pure form by Roscoe, who in 1867 reduced the chloride with hydrogen.

Vanadium of 99.3 to 99.8% purity was not produced until 1922.

Properties

Pure vanadium is a bright white metal, and is soft and ductile. It has good corrosion resistance to alkalis, sulfuric and hydrochloric acid, and salt water, but the metal oxidizes readily above 660oC. It is intermediate between the metals and the non-metals, having both basic and acid properties.

The metal has good structural strength and a low fission neutron cross section, making it useful in nuclear applications.

Sources

Vanadium is never found unbound in nature.  It is however, found in about 65 different minerals among which are carnotite, roscoelite, vanadinite, and patronite, important sources of the metal. Vanadium is also found in phosphate rock and certain iron ores, and is present in some crude oils in the form of organic complexes. It is also found in small percentages in meteorites.

Commercial production from petroleum ash holds promise as an important source of the element. High-purity ductile vanadium can be obtained by reduction of vanadium trichloride with magnesium or with magnesium-sodium mixtures.

Much of the vanadium metal being produced is now made by calcium reduction of V2O5 in a pressure vessel, an adaption of a process developed by McKechnie and Seybair.

Uses

Vanadium is used in producing rust resistant and high speed tool steels. Alloys of vanadium include special stainless steel used in surgical instruments and tools. When mixed with aluminum in titanium alloys, vanadium is used in jet engines and high-speed airframes. Vanadium steel alloys are used in axles, crankshafts, gears, and other critical componenets. It is an important carbide stabilizer in making steels.

About 80% of the vanadium now produced is used as ferrovanadium or as a steel additive. Vanadium foil is used as a bonding agent in cladding titanium to steel.

Vanadium also finds use in nuclear applications because of its low fission neutron cross section.

In biology, a vanadium atom is an essential component of some enzymes, particularly the vanadium nitrogenase used by some nitrogen-fixing microorganisms. Vanadium is essential for electron transfer chain of ascidians, or sea squirts. The concentration of vanadium in their bodies is one million times higher than the concentration of vanadium in the water 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.

Vanadium compounds are used as catalysts in producing maleic anhydride and sulfuric acid. Vanadium pentoxide (V2O5) is used as a catalyst, dye and color-fixer. It is also used to produce a superconductive magnet with a field of 175,000 gauss. Glass coated with vanadium dioxide (VO2) can block infrared radiation (and not visible light) at some specific temperature.

Isotopes

Natural vanadium is a mixture of two isotopes, 50V (0.24%) and 51V (99.76%). 50V is slightly radioactive, having a half-life of > 3.9 x 1017 years. Nine other unstable isotopes are recognized. 15 radioisotopes have been characterized with the most stable being V-50 with a half-life of 1.4E17 years. Vanadium does include 1 meta state.

Hazards

Vanadium and its compounds are toxic and should be handled with care. Vanadium compounds act chiefly as an irritant to the conjunctiva and respiratory tract. Acute and chronic exposure can give rise to conjunctivitis, rhinitis, reversible irritant of the respiratory tract, and to bronchitis, broncho spasms, and asthma-like diseases in more severe cases. The maximum allowable concentration of V2O5 dust in air is about 0.05 (8-hour time-weighted average - 40-hour week).