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.
At a glance
- Atomic number
- 74
- Atomic mass
- 183.841 u
- Phase
- Solid
- Density
- 19.25 g/cm³
- Melting point
- 3,695 K
- Boiling point
- 6,203 K
- First ionization energy
- 758.8 kJ/mol
- Electronegativity
- 2.36
- Electron affinity
- 78.76 kJ/mol
- Molar heat capacity
- 24.27 J/(mol·K)
- Period
- 6
- Appearance
- grayish white, lustrous
Conditions and isotopes affect measured properties. Some properties of short-lived elements are predicted. Electronegativity uses the Pauling scale.
Tungsten’s orbitals use a hydrogen-like approximation. Every orbital of each visible subshell is shown: in Shapes as the surface holding half its probability, with light and dark shades for opposite signs of the wavefunction; in Cloud as dots where its electrons are likely to be. Sizes are stepped by shell, like the Shell model.
54 is the [Xe] core total across five shells.
Preparing the orbital view…
74 protons110 neutrons
Tungsten-184: its most common form in nature, or its longest-lived if it has none. The nucleus is drawn far too big: it’s about 100,000 times smaller than the atom.
Turn up the heat
A step of 1 K is the same size as 1 °C, so the two scales are always 273.15 apart. Fahrenheit is different: its degrees are smaller and it starts elsewhere, so water freezes at 273.15 K, 0 °C and 32 °F.25 °C · 77 °FSolid
At this temperature, tungsten is a solid.
At normal atmospheric pressure (1 atm). The temperature scale is logarithmic. The particle box is schematic: real samples hold vastly more atoms, and spacing and speeds are not to scale.
Pull the electrons off
WNeutral atom · no charge
A neutral tungsten atom. Removing its first electron takes 759 kJ/mol.
Tungsten’s outer shell holds 2 electrons. Electron 3 is the first from an inner shell: it sits closer to the nucleus with less shielding, so removing it takes 1.6× as much energy as the one before. Each dashed line on the chart marks another jump, into a shell even closer to the nucleus.
What does this tell us?
- The jump after tungsten’s outer electrons is small (×1.6), because the electrons in the shell below have similar energies. That’s typical of transition metals, and it’s why many of them, such as iron (Fe²⁺ and Fe³⁺), can form more than one kind of ion.
- Within a shell the steps rise gently. Each electron removed leaves fewer electrons pushing the others away, while the nucleus pulls just as hard, so the next one is held a little more tightly.
Show the values as a table
| Electron | Shell | Energy (kJ/mol) | × previous | Value |
|---|---|---|---|---|
| 1 | 6 | 759 | – | Measured |
| 2 | 6 | 1,580 | 2.1 | Estimated |
| 3 | 5 | 2,509 | 1.6 | Estimated |
| 4 | 5 | 3,686 | 1.5 | Estimated |
| 5 | 5 | 4,979 | 1.4 | Estimated |
| 6 | 5 | 6,249 | 1.3 | Estimated |
| 7 | 5 | 11,772 | 1.9 | Estimated |
| 8 | 5 | 13,624 | 1.2 | Estimated |
| 9 | 5 | 15,457 | 1.1 | Estimated |
| 10 | 5 | 17,271 | 1.1 | Estimated |
| 11 | 5 | 20,156 | 1.2 | Estimated |
| 12 | 5 | 22,346 | 1.1 | Estimated |
| 13 | 5 | 24,922 | 1.1 | Estimated |
| 14 | 5 | 28,048 | 1.1 | Estimated |
| 15 | 4 | 31,387 | 1.1 | Estimated |
| 16 | 4 | 34,918 | 1.1 | Estimated |
| 17 | 4 | 37,427 | 1.1 | Estimated |
| 18 | 4 | 40,591 | 1.1 | Estimated |
| 19 | 4 | 44,586 | 1.1 | Estimated |
| 20 | 4 | 48,494 | 1.1 | Estimated |
| 21 | 4 | 52,430 | 1.1 | Estimated |
| 22 | 4 | 57,361 | 1.1 | Estimated |
| 23 | 4 | 61,809 | 1.1 | Estimated |
| 24 | 4 | 66,150 | 1.1 | Estimated |
| 25 | 4 | 70,830 | 1.1 | Estimated |
| 26 | 4 | 75,683 | 1.1 | Estimated |
| 27 | 4 | 80,411 | 1.1 | Estimated |
| 28 | 4 | 85,042 | 1.1 | Estimated |
| 29 | 4 | 109,241 | 1.3 | Estimated |
| 30 | 4 | 113,853 | 1 | Estimated |
| 31 | 4 | 118,716 | 1 | Estimated |
| 32 | 4 | 123,829 | 1 | Estimated |
| 33 | 4 | 128,818 | 1 | Estimated |
| 34 | 4 | 133,806 | 1 | Estimated |
| 35 | 4 | 140,859 | 1.1 | Estimated |
| 36 | 4 | 145,924 | 1 | Estimated |
| 37 | 4 | 151,395 | 1 | Estimated |
| 38 | 4 | 156,470 | 1 | Estimated |
| 39 | 4 | 176,549 | 1.1 | Estimated |
| 40 | 4 | 181,672 | 1 | Estimated |
| 41 | 4 | 187,239 | 1 | Estimated |
| 42 | 4 | 192,469 | 1 | Estimated |
| 43 | 4 | 207,357 | 1.1 | Estimated |
| 44 | 4 | 213,233 | 1 | Estimated |
| 45 | 4 | 227,175 | 1.1 | Estimated |
| 46 | 4 | 232,925 | 1 | Estimated |
| 47 | 3 | 391,441 | 1.7 | Measured |
| 48 | 3 | 403,309 | 1 | Estimated |
| 49 | 3 | 415,755 | 1 | Estimated |
| 50 | 3 | 428,974 | 1 | Estimated |
| 51 | 3 | 441,710 | 1 | Estimated |
| 52 | 3 | 454,349 | 1 | Estimated |
| 53 | 3 | 475,383 | 1 | Estimated |
| 54 | 3 | 488,505 | 1 | Estimated |
| 55 | 3 | 502,592 | 1 | Estimated |
| 56 | 3 | 516,004 | 1 | Estimated |
| 57 | 3 | 551,800 | 1.1 | Estimated |
| 58 | 3 | 563,474 | 1 | Estimated |
| 59 | 3 | 576,017 | 1 | Estimated |
| 60 | 3 | 587,885 | 1 | Estimated |
| 61 | 3 | 636,417 | 1.1 | Estimated |
| 62 | 3 | 649,829 | 1 | Estimated |
| 63 | 3 | 675,397 | 1 | Estimated |
| 64 | 3 | 687,940 | 1 | Estimated |
| 65 | 2 | 1,501,891 | 2.2 | Estimated |
| 66 | 2 | 1,533,731 | 1 | Estimated |
| 67 | 2 | 1,568,080 | 1 | Estimated |
| 68 | 2 | 1,600,499 | 1 | Estimated |
| 69 | 2 | 1,782,663 | 1.1 | Estimated |
| 70 | 2 | 1,820,871 | 1 | Estimated |
| 71 | 2 | 1,868,149 | 1 | Estimated |
| 72 | 2 | 1,899,482 | 1 | Calculated |
| 73 | 1 | 7,639,896 | 4 | Calculated |
| 74 | 1 | 7,791,761 | 1 | Calculated |
Successive ionization energies of gas-phase atoms and ions from the NIST Atomic Spectra Database. Solid bars are measured; hatched bars were estimated from nearby measurements or calculated from quantum theory, as is usual for highly charged ions. Electrons are taken from the outermost shell first, a simplification: electrons in different subshells of the same shell also differ in energy. On the log scale each gridline is 10 times the one below.
Turn up the current on a light bulb
An old-style light bulb is just a coil of tungsten wire. Push a current through it and the wire heats up until it glows. Turn up the current and watch the colour change, then see how close the filament gets to melting.
- Current
- 0.00 A
- Resistance
- 57 Ω
- Visible light
- almost none
Switched off. Turn up the current to heat the filament.
Cold, the filament’s resistance is only about 57 Ω; glowing, it’s about 882 Ω. So for a split second after you switch on, around 15 times the normal current rushes in, which is why bulbs usually fail at the moment you switch them on.
Why tungsten?
- Gold1,064 °C
- Copper1,085 °C
- Iron1,538 °C
- Platinum1,768 °C
- Tantalum3,017 °C
- Osmium3,033 °C
- Tungsten3,422 °C
The bars show each metal’s melting point; the orange line is the filament now. A normal bulb at 2,427 °C would have melted gold, copper, iron and platinum long ago. Only a handful of metals survive it, and tungsten melts hottest of all.
Even at room temperature the filament gives out a faint glow, but it’s all far infrared: the peak is off the right of the chart.
A century of filaments
- Edison’s carbon, 1879
The first practical bulbs used carbon threads. Carbon doesn’t melt, but it slowly boils away, blackening the glass, so the filaments had to run cooler and redder.
- Osmium, tantalum, tungsten
Osmium (1898) and tantalum (1902) came next. Tungsten arrived in 1904, but it was brittle until William Coolidge found a way to draw it into fine wire; by 1911 it was in bulbs everywhere.
- Why they were phased out
Even at its best, a glowing wire turns only a few percent of its power into light. LEDs give the same light for a fraction of the energy, so many countries have banned most filament bulbs.
A 60 W, 230 V bulb, calibrated to a typical 2,700 K at its rated current. The temperature comes from balancing the electrical heating against the heat radiated, using tungsten’s measured resistivity (Desai et al., 1984); it ignores the heat lost through the supports. Real filaments radiate a little less than an ideal blackbody, and because our eyes are most sensitive to green, a real 60 W bulb’s efficiency measured by brightness is only about 2%. Melting points from the element data. Bulb history from Wikipedia.
How does it compare?
Density
19.3 g/cm³8th highest of 99
Melting point
3,695 KThe highest melting point of 96 elements
Boiling point
6,203 KThe highest boiling point of 97 elements
Electronegativity
2.3613th highest of 96
First ionization energy
759 kJ/mol37th highest of 99
Elements 1–99 from the reference data; heavier elements are left out because only a few atoms have ever been made, so their bulk properties are predictions. First ionization energies come from NIST. Density uses a logarithmic scale, because gases are around a thousand times less dense than solids; gas densities are at 0 °C and 1 atm. Melting and boiling points are at normal pressure. Everyday temperatures and light sources in the pictures are approximate. Hover over a dot to see the element, or click it to compare.
Keep exploring
Explore the stories, imagery, and reference data in more depth. Properties with no value in the reference are marked unavailable.
- TungstenRoyal Society of Chemistry
- TungstenWikipedia
- Quantum numbers and electron configurationsPurdue
- Hydrogenic wavefunctionsNIST
- Ionization energiesNIST Atomic Spectra Database