Rhenium
Element 75 · Transition Metal
Rhenium is a silvery-white metal with an extraordinary tolerance for heat: it has the third-highest melting point and one of the highest boiling points of all elements. It shows the widest range of oxidation states in its group, from -1 up to +7.
Because it strengthens nickel superalloys against creep at extreme temperatures, rhenium is essential in single-crystal turbine blades of jet engines. It also makes precise thermocouples and catalysts that reform petroleum into high-octane fuel.
Key facts
| Atomic number | 75 |
|---|---|
| Atomic weight | 186.21 |
| Category | Transition Metal |
| Group / Period | 7 / 6 |
| Block | d |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d5 |
| Common oxidation states | +7, +4 |
| State at STP | Solid |
| Electronegativity | 1.90 |
| Density | 21.02 g/cm³ |
| Melting point | 3186 °C |
| Boiling point | 5596 °C |
Occurrence
Rhenium is among the rarest elements in Earth's crust, recovered in tiny traces from molybdenite and copper ores during refining.
Applications
Jet engine turbine superalloys
High-temperature thermocouples
Petroleum reforming catalysts
Electrical contacts
Common compounds
- rhenium heptoxide
- ammonium perrhenate
Rhenium was the last naturally occurring stable element to be discovered, in 1925 — and it remains among the rarest elements in Earth's crust.
Data source: IUPAC standard atomic weights 2021