Tungsten
Tungsten, also known as wolfram, is a chemical element with symbol W and atomic number 74. The word tungsten comes from the Swedish language tung sten, which directly translates to heavy stone. Its name in Swedish is volfram, however, in order to distinguish it from scheelite, which in Swedish is alternatively named tungsten.
Identity
- Atomic mass
- 183.841 u
- Category
- Transition metals
- Group
- 6
- Period
- 6
- Block
- d
- Oxidation States
- +2, +3, +4, +5, +6
- Phase (25 °C)
- Solid
- Appearance
- grayish white, lustrous
Electronic Structure
- Electron configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d4
- Short configuration
- [Xe] 4f14 5d4 6s2
- Electrons per shell
- 2, 8, 18, 32, 12, 2
- Electronegativity (Pauling)
- 2.36
- Electron affinity
- 78.8 kJ/mol
- 1st ionization energy
- 770 kJ/mol
- Ionization energies
- 770 · 1700 kJ/mol
Physical properties
- Melting point
- 3421.8 °C (3695 K)
- Boiling point
- 5929.9 °C (6203 K)
- Density
- 19.25 g/cm³
- Molar heat capacity
- 24.3 J/(mol·K)
Chemical behavior of tungsten
Tungsten has an incomplete d-shell electron configuration ([Xe] 4f¹⁴ 5d⁴ 6s²). It shows oxidation states ranging from +2 to +6, with the +6 (VI) state being the most common, thermodynamically stable and representative in its compounds such as tungsten trioxide (WO₃) and tungstates. It is a dense, steel-gray transition metal that boasts the highest melting point of all pure chemical elements (3,422 °C) and the lowest vapor pressure at high temperatures. It shows notable resistance to attack by acids at room temperature due to surface passivation.
Reactivity
W + 3 O₂ (heat) → WO₃
At room temperature it is inert toward oxygen, but above 400 °C it oxidizes rapidly in air forming yellowish tungsten trioxide.
W + 2 NaOH + 3 H₂O₂ → Na₂WO₄ + 4 H₂O
It resists most simple acids, but actively dissolves in alkaline mixtures of sodium hydroxide with hydrogen peroxide, or in oxidizing nitrate melts.
W + 3 F₂ → WF₆
It reacts spontaneously and exothermically with fluorine gas at room temperature producing gaseous tungsten hexafluoride.
W + C → WC
At sintering temperatures above 1,400 °C it combines with carbon to form tungsten monocarbide, of extreme hardness.
Notable compounds
| Compound | Formula | Use or importance |
|---|---|---|
| Tungsten carbide | WC | Widia; ultra-hard cermet used in mining drill bits, machined milling cutters and cutting tools |
| Tungsten trioxide | WO₃ | Yellow pigment, petrochemical catalyst and electrochromic material for smart windows that darken with voltage |
| Sodium tungstate | Na₂WO₄ | Flame retardant for textiles, reagent in clinical biochemistry and precursor of tungsten pigments |
| Tungsten hexafluoride | WF₆ | Very heavy inorganic gas used in the microelectronics industry to deposit tungsten metal contacts on integrated circuits |
Electron shell distribution
View in the atom builderIsotopes
Natural tungsten consists of five isotopes: four stable ones (¹⁸²W at 26.50%, ¹⁸³W at 14.31%, ¹⁸⁴W at 30.64% and ¹⁸⁶W at 28.43%) and a primordial radionuclide with a colossal half-life, tungsten-180 (¹⁸⁰W, 0.12%, with a calculated alpha-decay half-life of 1.8 × 10¹⁸ years). The hafnium-182 / tungsten-182 radioisotopic pair is the fundamental geochemical clock for dating core–mantle differentiation in the primitive Earth and in asteroids.
Occurrence and production
It is a scarce element in the Earth's crust (around 1 to 1.5 ppm). It never appears free in nature. Its most important commercial minerals are scheelite (calcium tungstate, CaWO₄), which fluoresces under ultraviolet light, and the wolframite series (mixed iron and manganese tungstate, (Fe,Mn)WO₄). China dominates world mining production with over 80% of the market. It is extracted by treating the concentrates with concentrated alkaline solutions to obtain ammonium paratungstate (APT), which is calcined to oxide and reduced with hydrogen gas above 700 °C to yield pure tungsten powder.
History and origin of the name
In 1781 the Swedish chemist Carl Wilhelm Scheele isolated a new mineral acid from the mineral scheelite and proposed that it contained an unknown metal. Two years later, in 1783, the Spanish chemist brothers Juan José and Fausto Elhúyar achieved the first isolation of elemental tungsten in the laboratories of Vergara (Spain) by reducing the acid extracted from wolframite with charcoal. The name 'tungsten' comes from Swedish 'tung sten' (heavy stone), while its Spanish synonym 'wolframio' derives from the German 'Wolf-Rahm' (wolf's foam or froth).
Applications and relevance of tungsten
Uses of the element
Over 60% of tungsten is consumed as tungsten carbide for machining, milling, metal-cutting tools and drill bits for tunneling and mining. Thanks to its unsurpassed melting point and heat resistance, it is the historic material for incandescent light-bulb filaments, electrodes for gas tungsten arc welding (TIG), rotating anodes in medical X-ray tubes and penetrator projectiles for kinetic-energy armor.
Uses of its compounds
Tungsten hexafluoride is crucial in manufacturing 3D NAND memory chips; tungstates are used in scintillators for positron emission tomography (PET); and tungsten trioxide is employed in electrochromic windows that regulate sunlight in sustainable buildings.
Health, safety and environment
Biological role
Tungsten is the heaviest known chemical element with a demonstrated biological role in nature, forming part of the active site of certain metalloenzyme proteins (such as aldehyde ferredoxin oxidoreductase) in hyperthermophilic archaea and bacteria from deep hydrothermal vents. In mammals it lacks physiological function and acts as an antagonist of molybdenum.
Safety
The bulk metal and machined parts are totally stable and inert. Prolonged inhalation of tungsten carbide dusts in industrial settings without proper ventilation can cause pulmonary fibrosis or so-called 'hard metal disease', often aggravated by the presence of cobalt as the binder.
Environment
Tungsten shows moderate mobility in alkaline soils, but generally low toxicity compared with other heavy metals such as lead or cadmium, so its substitution in military hunting ammunition has reduced lead pollution in wetlands.
Frequently asked questions about Tungsten
Why does tungsten resist so much heat without melting?
Tungsten melts at a record 3,422 °C, the highest of all known metals. Its atoms have electrons arranged in orbitals that overlap with enormous force, creating exceptionally rigid and compact metallic bonds. For this reason it withstands extreme heat without deforming, and it is a historic material in light-bulb filaments and rocket nozzles.
How does tungsten perform in kinetic-energy armor-piercing military projectiles?
Kinetic-energy penetrators (APFSDS darts) use no chemical explosives: they perforate heavy tank armor relying exclusively on the metal's enormous density (19.3 g/cm³) and hardness at supersonic speeds (over 1,500 m/s). Heavy rods of tungsten alloys concentrate colossal kinetic energy on a diminutive contact point, punching through thick steel armor by means of a hypervelocity hydrodynamic flow phenomenon without deforming on impact.
What is 'widia' material and why is it so hard?
The word 'widia' comes from German and means 'like diamond'. It is a compound of tungsten carbide combined with cobalt that offers extreme hardness and unsurpassed wear resistance. Drill bits for boring into concrete, circular saws and industrial milling cutters carry widia tips because they can cut hardened steel without losing their edge or chipping.
How can smart windows change transparency using tungsten?
Some smart windows incorporate a thin layer of tungsten trioxide. When a small voltage is applied, ions and electrons enter the material and change its optical properties, making the layer darken. By reversing the process it can recover part of its transparency. This technology helps regulate the entry of light and heat into buildings, although its cost and performance depend on the system design.
What was the historic feat of the Elhúyar brothers in isolating tungsten in Vergara?
In September 1783, the Enlightenment chemists Juan José and Fausto Elhúyar were working at the Real Seminario Patriótico of Vergara (Gipuzkoa). After purifying the tungstic acid obtained from the wolframite mineral, they introduced the powder into a crucible with charcoal at extreme forge temperatures for an hour and a half. On breaking the crucible they obtained a hard, brittle metallic button never seen before: pure tungsten, constituting the only discovery of a chemical element made on Spanish soil.
Can tungsten play a role in some microorganism enzymes?
Yes. Some archaea and bacteria use tungsten in enzymes that take part in chemical reactions essential to their metabolism. These microorganisms can live in extreme environments, although not all inhabit hydrothermal vents and not all depend on tungsten. Their study helps us understand how life makes use of different chemical elements and how enzymes work under conditions very different from the usual ones.
How does the hafnium–tungsten system calculate the exact time when Earth's core formed?
The extinct isotope hafnium-182 decayed into tungsten-182 with a half-life of nine million years in the dawn of the solar system. Hafnium has an affinity for mantle silicates, while tungsten has an affinity for metallic iron. When the Earth's core differentiated, it dragged away almost all the tungsten. By measuring the residual excess of tungsten-182 in mantle rocks, geologists calculated that the planetary core formed in barely thirty million years.
Main sources consulted: PubChem, Royal Society of Chemistry, NIST, IUPAC. Last revision: November 2026.