Vanadium – facts and properties
- Symbol
- V
- Atomic number
- 23
- Atomic mass
- 50.942 u
- Period
- 4
- Group
- 5
- Category
- transition metal
- Electron configuration
- [Ar] 3d³ 4s²
- Electronegativity
- 1.63
- Atomic radius
- 171 pm
- Valence electrons
- 5
- State at standard conditions
- solid
- Melting point
- 1910 °C
- Boiling point
- 3407 °C
- Density
- 6 g/cm³
- Discovered
- 1801
Vanadium is a hard, silvery-grey transition metal with atomic number 23. It owes its name to the vivid colours of its compounds, which are violet, green, blue or yellow depending on the oxidation state. The pure metal is rarely seen. Its real importance lies in steel, where small additions make tools, springs and axles much stronger and tougher. In future, vanadium may also play a part in large batteries that store electricity from wind and solar power.
Position in the periodic table
Occurrence and extraction
Vanadium is more abundant in the Earth's crust than copper or zinc, but it is widely dispersed. It is found in many minerals, such as vanadinite, a red lead mineral, and carnotite, which also contains uranium. Larger amounts occur in titanium-bearing magnetite ores. Crude oil, coal and oil shale contain vanadium too, and it builds up in their residues and fly ash. The leading producers are China, Russia, South Africa and Brazil.
Its discovery is a tangled story. The Spanish-Mexican mineralogist Andrés Manuel del Río found the element in 1801 in a lead ore from Mexico. A French chemist, however, judged his sample to be impure chromium, and del Río withdrew his claim. In 1830 the Swede Nils Gabriel Sefström rediscovered the element in Swedish iron ore. He named it after Vanadís, a name of the Norse goddess Freyja, because of its beautiful compounds. Nearly pure vanadium metal was first made in 1867 by the English chemist Henry Roscoe.
Today vanadium is mostly a by-product. When vanadium-bearing iron ores are smelted, it collects in the slag, from which it is recovered as vanadium pentoxide. For the steel industry it is then reduced together with iron to give ferrovanadium.
Properties and reactions
Vanadium is in period 4 and group 5, and its electron configuration is [Ar] 3d³ 4s². Its electronegativity is 1.63. The metal has a density of 6 g/cm³, melts at 1910 °C and boils at 3407 °C. Pure vanadium is tough and easy to shape, but even small traces of oxygen, nitrogen or carbon make it hard and brittle. A thin oxide film protects it in air, and it holds up well against salt water and many acids.
What makes vanadium chemically special is its range of oxidation states. It can take the states plus two, plus three, plus four and plus five, and each has its own colour in aqueous solution: violet, green, blue and yellow. A popular classroom experiment shows this. If zinc is added to an acidified yellow vanadate solution, the colour changes to blue, then green and finally violet as the zinc reduces the vanadium step by step.
Its most important compound is vanadium pentoxide, V₂O₅, an orange powder. It works as a catalyst because it can easily give up oxygen and take it back again. It is toxic and classified in the EU as a carcinogen.
Uses in everyday life and technology
Most vanadium goes into steel. Even small additions form tiny, hard carbides that give the steel a fine-grained structure, making it stronger, tougher and more wear-resistant. Chrome vanadium steel is a typical material for spanners, drill bits and springs, and high-strength structural steels for bridges, pipelines and reinforcing bars also contain vanadium. Henry Ford already used vanadium steel for parts of his Model T, because they were lighter and still able to carry heavy loads.
In aerospace and medicine, a titanium alloy containing aluminium and vanadium is used for parts such as engine components and hip replacements. Vanadium pentoxide is the catalyst in the contact process for making sulfuric acid, where it speeds up the oxidation of sulfur dioxide to sulfur trioxide.
A newer application is the vanadium redox flow battery. It stores energy in two tanks of vanadium solutions in different oxidation states. These batteries hardly wear out, can be scaled up simply by using larger tanks, and are therefore well suited to storing electricity from wind farms and solar parks.
Molecules containing this element
- Bismuth vanadate BiVO4
- Vanadium(V) oxide V2O5
Quick question
What is the atomic number of vanadium (V)?
FAQ
What is vanadium used for?
Mainly for steel. Small amounts of vanadium make steel stronger and more wear-resistant, for example in chrome vanadium tools. Vanadium is also found in titanium alloys for aircraft and implants, acts as a catalyst in sulfuric acid production and is used in large redox flow batteries.
Why does vanadium have so many colours?
In its compounds vanadium can give up two, three, four or five electrons. In the states plus two, plus three and plus four, a different number of d electrons is left behind, and these absorb different parts of visible light, giving violet, green or blue solutions. Vanadium(V) has no d electrons left; its yellow colour arises because light shifts electrons from oxygen to vanadium.
Is vanadium found in living things?
Yes, some organisms concentrate vanadium strongly. Certain sea squirts store it in their blood cells, and the fly agaric mushroom contains a vanadium compound called amavadin. Some algae and bacteria use vanadium in enzymes. Whether humans need vanadium has not been shown.