Encyclopedia > Vanadium

  Article Content

Vanadium

Titanium - Vanadium - Chromium
V
Nb  
 
 
General
Name, Symbol, NumberVanadium, V, 23
Chemical series Transition metals
Group, Period, Block5 [?], 4 , d
Density, Hardness 6110 kg/m3, 7.0
Appearance silvery grey metallic
Atomic Properties
Atomic weight 50.9415 amu
Atomic radius (calc.) 135 (171) pm
Covalent radius 125 pm
van der Waals radius n/a pm
Electron configuration [Ar]3d34s2
e- 's per energy level2, 8, 11, 2
Oxidation states (Oxide) 5,3 (amphoteric)
Crystal structure body centered cubic
Physical Properties
State of matter solid (__)
Melting point 2175 K (3456 °F)
Boiling point 3682 K (6168 °F)
Molar volume 8.32 ×10-3 m3/mol
Heat of vaporization 0.452 kJ/mol
Heat of fusion 20.9 kJ/mol
Vapor pressure 3.06 Pa at 2175 K
Velocity of sound 4560 m/s at 293.15 K
Miscellaneous
Electronegativity 1.63 (Pauling scale)
Specific heat capacity 490 J/(kg*K)
Electrical conductivity 4.89 106/m ohm
Thermal conductivity 30.7 W/(m*K)
1st ionization potential 650.9 kJ/mol
2nd ionization potential 1414 kJ/mol
3rd ionization potential 2830 kJ/mol
4th ionization potential 4507 kJ/mol
5th ionization potential 6298.7 kJ/mol
Most Stable Isotopes
isoNAhalf-life DMDE MeVDP
48V{syn.}15.9735 days ε4.01248Ti
49V{syn.}330 daysε0.60249Ti
50V{syn.}1.4E17 yε
β
2.208
1.037
50Ti
50Cr
51V100%vanadium is stable with 28 neutrons
SI units & STP are used except where noted.
Vanadium 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.

Table of contents

Notable Characteristics Vanadium is a soft and ductile, bright white metal. It has good resistance to corrosion by alkalis, sulphuric 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. It is intermediate between the metals and the non-metals, having both basic and 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 also rarely seen. Applications Approximately 80% of vanadium produced is used as ferrovanadium or as a steel additive. Other uses;

History Vanadium (Scandinavian goddess, Vanadis) was originally discovered by Andres Manuel del Rio[?] (a Spanish mineralogist) at Mexico City in 1801, who called it "brown lead" (now named vanadinite). Through experimentation, he saw that the colors it exhibited were reminiscent of chromium, so he named the element panchromium. He later renamed this compound erythronium, since most of the salts turned red when heated. 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 statement of the French chemist.

In 1831, Sefström of Sweden rediscovered vanadium in a new oxide he found while working with some iron ores and later that same year Friedrich Wöhler[?] confirmed del Rio's earlier work.

Metallic vanadium was isolated by Henry Enfield Roscoe[?] in 1867, who reduced the vanadium chloride[?] (VCl3) with hydrogen. The name vanadium comes from Vanadis[?], the goddess of beauty in Scandinavian mythology because the element has beautiful multicolored chemical compounds. Biological Role 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 to 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. Occurrence Vanadium is never found unbound in nature but it does occur in about 65 different minerals among which are patronite[?] (VS4), vanadinite [Pb5(VO4)3Cl], and carnotite[?] [K2(UO2)2(VO4)2.3H2O]. Vanadium is also present in bauxite, and in carbon containing deposits such as crude oil, coal, oil shale and tar sands. The spectra of vanadium has also been detected in light from the sun and some other stars.

Much of the vanadium metal being produced is now made by calcium reduction of V2O5 in a pressure vessel. Vanadium is usually recovered as a by-product or co-product, and so world resources of the element are not really indicative of available supply. Compounds Vanadium pentoxide[?] (V2O5) is used as a catalyst, dye and color-fixer. Isotopes Naturally occurring vanadium is composed of 1 stable isotope; V-51. 15 radioisotopes have been characterized with the most stable being V-50 with a half-life of 1.4E17 years, V-49 with a half-life of 330 days, and V-48 with a half-life of 15.9735 days. All of the remaining radioactive isotopes have half-lifes that are less than 1 hour and the majority of these have half lifes that are less than 10 seconds. This element also has 1 meta state.

The isotopes of vanadium range in atomic weight from 43.981 amu (V-43) to 59.959 amu (V-59). The primary decay mode before the most abundant stable isotope, V-51, is electron capture and the primary mode after is beta decay. The primary decay products before V-51 are element 22 (titanium) isotopes and the primary products after are element 24 (chromium) isotopes. Precautions Powdered metallic vanadium is a fire hazard, and vanadium compounds should be considered highly toxic. Vanadium compounds may cause lung cancer if inhaled.

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.

External Links



All Wikipedia text is available under the terms of the GNU Free Documentation License

 
  Search Encyclopedia

Search over one million articles, find something about almost anything!
 
 
  
  Featured Article
Layer 2

... NetBEUI[?], ATP[?], NBP[?], AEP[?], RTMP[?] 3 - NetworkIP, IPX, NWLink[?], NetBEUI[?], DDP[?] 2 - Data LinkEthernet, Token Ring, PPP, ODI[?], NDIS[?] ...