Vanadium
Element 23 · Transition Metal
Vanadium is a hard, silvery-gray transition metal named after Vanadis, a Norse goddess of beauty — a nod to the vivid colors of its compounds. Each oxidation state has a signature color: +2 violet, +3 green, +4 blue, and +5 yellow, making vanadium a favorite for classroom demonstrations of variable valency.
Its main industrial role is metallurgical: small additions to steel dramatically increase strength, hardness, and fatigue resistance, essential for tools and springs. A newer, growing use is the vanadium redox flow battery, which stores large amounts of renewable energy for power grids.
Key facts
| Atomic number | 23 |
|---|---|
| Atomic weight | 50.942 |
| Category | Transition Metal |
| Group / Period | 5 / 4 |
| Block | d |
| Electron configuration | [Ar] 3d3 4s2 |
| Common oxidation states | +5, +4, +3, +2 |
| State at STP | Solid |
| Electronegativity | 1.63 |
| Atomic radius | 171 pm |
| Density | 6.11 g/cm³ |
| Melting point | 1910 °C |
| Boiling point | 3407 °C |
Occurrence
Vanadium occurs in about 65 different minerals, including vanadinite and carnotite, and is also recovered from crude oil residues and steel slag. It is never found as a free metal and is typically extracted as a byproduct of other mining operations.
Applications
High-strength low-alloy steels for tools, springs, and axles contain vanadium
Vanadium redox flow batteries store grid-scale renewable energy
Titanium-aluminium-vanadium alloys serve in jet engines and airframes
Vanadium pentoxide catalyzes sulfuric acid production by the contact process
Ceramic glazes and pigments use vanadium compounds for color
Common compounds
- vanadium pentoxide
- vanadium tetrachloride
- vanadyl sulfate
- ammonium metavanadate
Vanadium compounds display nearly every color of the rainbow depending on oxidation state.
Data source: IUPAC standard atomic weights 2021