Rhenium (Re)
“The last stable element ever discovered — a 1925 Berlin find named after the Rhine, rarer in the crust than gold, yet at work in every jet engine.”
How its electrons are arranged
Computed from the aufbau principle, with known real-world exceptions applied automatically.
The notes
Characteristics
- Electron configuration [Xe] 4f¹⁴ 5d⁵ 6s² — period 6, group 7, d-block, seven valence electrons; like manganese above it, rhenium ranges through oxidation states from −1 all the way up to +7.
- Melting point 3186 °C — third-highest of all the elements after carbon and tungsten — while its boiling point ranks among the very highest known.
- One of the rarest elements in the crust at roughly one part per billion — scarcer than gold; it owns no ore of its own and is rescued only from molybdenite smelter flue dust.
- A refractory metal that keeps its strength, and resists corrosion and wear, even at white heat — exactly what white-hot turbine blades demand.
A silvery-grey metal of platinum-grade heft — density 21.02 g/cm³ — with a dense, gleaming look. It is one of the most heat-proof metals known, refusing to melt before 3186 °C, and its slow-grown crystals show beautiful curved, ridged faces.
Where you meet it
✦ Uses
- Nickel superalloy turbine blades: 3–6% rhenium in the newest single-crystal jet-engine and power-turbine blades lets them endure gases hotter than the alloy’s own melting point.
- Platinum–rhenium reforming catalysts in oil refineries — the chemistry behind the high-octane petrol priced at every filling station.
- Tungsten–rhenium thermocouples that faithfully read temperatures up to about 2300 °C inside furnaces and reactors.
- X-ray tube rotating anodes of W–Re alloy, plus filaments and electrical contacts where a long wear life matters.
◍ Everyday examples
- Everyone who flies — from a Biman jet to any wide-body abroad — is carried on rhenium-toughened blades in the engine’s hottest section.
- The octane priced at a Bangladeshi filling station has almost always been born over a platinum–rhenium reforming catalyst.
- Deep-furnace industries trust W–Re thermocouples to report temperatures where ordinary sensors would melt.
History & name
Mendeleev had left a labelled slot for it in 1869 as “dvi-manganese”, the heavier cousin of manganese that his table demanded. The hunt ended in 1925 in Berlin, where Walter Noddack, Ida Tacke and Otto Berg traced its X-ray fingerprints in columbite and platinum ores — and rhenium proved to be the last stable element ever discovered, since every later find has been radioactive. The team named it after Rhenus, the Latin name of the Rhine, honouring Ida Tacke’s Rhineland home. The first visible gram, in 1928, had to be cooked out of 660 kilograms of molybdenite — a fair measure of how scarce rhenium is.