Tungsten at a glance
- Atomic number
- 74
- Symbol
- W
- Atomic mass
- 183.84 u
- Category
- Transition metal
- Group / period
- 6 / 6
- Electron configuration
- [Xe] 4f 14 5d 4 6s 2
- State at 25 °C
- Solid
- Melting point
- 3422 °C
- Boiling point
- 5555 °C
- Density
- 19.25 g/cm³
- Electronegativity
- 2.36
- 1st ionization energy
- 770 kJ/mol
- Oxidation states
- +6, +4
- Discovered
- 1783
Atomic structure
A neutral tungsten atom has 74 protons and 74 electrons, and its most common isotope carries about 110 neutrons. One atom weighs about 3.05 × 10⁻²⁵ kg, so a mole of tungsten (6.022 × 10²³ atoms) weighs 183.84 g. That nucleus holds 1.49 neutrons for every proton, typical of heavy nuclei, which need extra neutrons to hold together against the protons' repulsion. Its symbol W comes from wolfram (the German name). The electrons fill 6 shells (K 2, L 8, M 18, N 32, O 12, P 2), which gives the configuration [Xe] 4f 14 5d 4 6s 2. As a d-block element, both its outer s electrons and its inner d electrons can take part in bonding, which is why it shows more than one oxidation state. It has 4 stable isotopes: W-182, W-183, W-184 and W-186. Its most common isotope, W-184, has the same mass number as Os-184: isobars, nuclei of different elements with 184 nucleons each.
Physical properties
At room temperature (25 °C) tungsten is a solid. It melts at 3422 °C and boils at 5555 °C, so it stays liquid across a 2133-degree range. It stays solid in a welding arc but would melt in the surface of the Sun. That is the 2nd highest melting point of any element. Its density is 19.25 g/cm³, 19.3 times as dense as water. Its atoms have a radius of about 135 pm (Tantalum next door is 145 pm). In the solid, its atoms pack into a body-centred cubic lattice.
Chemical behaviour
Its electronegativity is 2.36 on the Pauling scale. Pulling off its outermost electron takes 770 kJ/mol, more than Molybdenum above it (684 kJ/mol). A bond between tungsten and chlorine would be polar covalent, with an electronegativity difference of 0.8. It releases 79 kJ/mol when it gains an extra electron. Its common oxidation states are +6, +4, so in compounds you will usually meet it as W⁶⁺ and W⁴⁺. Group 6 also holds Chromium, Molybdenum and Seaborgium, which share its outer-shell pattern.
Where it comes from
It makes up 1.25 mg/kg of Earth's crust, the 57th most abundant element there. It was first identified in 1783, making it the 26th element to be discovered (counting the 11 known since antiquity together).