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75Re186.207
Transition metal

Rhenium

Rhenium is a dense, silvery-white transition metal discovered in 1925, among the last stable elements to be found and one of the rarest in Earth's crust. It's a small but essential ingredient in the alloys that let jet engines run at extreme temperatures.

Group · Period
7 · 6
At room temp
solid
Melts at
3459 K
Density
20.8 g/cm³
Discovered
1925

Uses

Rhenium’s scarcity means it’s used in small, carefully targeted amounts rather than in bulk. Its most important application is in nickel-based superalloys used for jet engine turbine blades, where adding even a modest percentage of rhenium substantially improves the alloy’s strength and resistance to deformation at the extreme temperatures inside a running engine. Rhenium is also used as a catalyst, most notably combined with platinum in the reforming process that refineries use to convert crude oil fractions into higher-octane gasoline.

History

Rhenium was discovered in 1925 by German chemists Walter Noddack, Ida Tacke, and Otto Berg, who detected it using X-ray spectroscopy in samples of platinum ore and other minerals. Its extreme scarcity and tendency to occur only in trace amounts within other metals’ ores had kept it hidden from earlier, less sensitive detection methods, making it one of the last naturally occurring stable elements to be confirmed. The team named it after the Rhine river, Rhenus in Latin, tying the element to the region where much of the research took place.

Fun facts

  • Rhenium is one of the rarest elements in Earth's crust, found only in trace amounts within certain other ores.
  • Small amounts of rhenium added to nickel-based superalloys let jet engine turbine blades withstand extremely high temperatures without losing strength.
  • Rhenium was one of the last naturally occurring stable elements to be discovered, identified only in 1925.

Frequently asked questions

What is rhenium used for if it's so rare?

Its scarcity means rhenium is used sparingly, in applications where a small amount makes a big difference. The most important is in nickel-based superalloys for jet engine turbine blades, where adding rhenium significantly improves how well the metal holds its strength at extreme temperatures. It's also used as a catalyst, particularly in refining petroleum into high-octane gasoline.

Why is rhenium so rare?

Rhenium doesn't form its own dedicated ore deposits in any significant way; instead it occurs in tiny concentrations within molybdenum and copper ores, and is recovered mainly as a byproduct of processing those. That scattered, low-concentration occurrence is what makes it one of the least abundant elements in the Earth's crust.

Why was rhenium discovered so much later than most other elements?

Because it's so scarce and thinly spread through other ores, rhenium's presence was extremely hard to detect using the chemical methods available to early chemists. It took the more sensitive technique of X-ray spectroscopy, developed in the early 20th century, for researchers to finally confirm it in 1925 — making it one of the last stable elements to be identified.

Compounds

3 notable compounds containing Re

  • NH4ReO4industrial

    Ammonium perrhenate

    A white, water-soluble crystalline salt that is the main commercial form in which rhenium is sold and shipped, since it is easily purified from ore-processing streams.

    Used for: Primary industrial source material for producing rhenium metal and its alloys

  • ReO2oxide

    Rhenium dioxide

    A dark brown to bluish-black, chemically inert solid in which rhenium sits in its intermediate +4 oxidation state.

    Used for: Laboratory intermediate in rhenium refining and catalyst preparation

  • Re2O7oxide

    Rhenium heptoxide

    A pale yellow, volatile solid and the most stable oxide of rhenium, reflecting rhenium's most common and highest, +7, oxidation state.

    Used for: Starting material for making other rhenium(VII) compounds and catalysts

Isotopes

41 known isotopes

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IsotopeNatural abundanceHalf-lifeDecay modeMass excessBinding energy / nucleonDecay width
Re-185 stable 37.4% Stable — -43,819.05 keV 7,991.01 keV —
Re-187 62.6% 4.33E+10 Y Beta-minus decay (100%), Alpha decay (0.0001%) -41,216.55 keV 7,977.95 keV 3.34 × 10-34 eV
Show all 41 isotopes
Re-159 — — Unknown -14,805 keV 7,795 keV —
Re-160 — 612 us Proton emission (89%), Alpha decay (11%) -16,878 keV 7,810 keV 7.45 × 10-13 eV
Re-161 — 0.44 ms Proton emission (100%), Alpha decay (1.4%) -20,842.82 keV 7,836.33 keV 1.04 × 10-12 eV
Re-162 — 107 ms Alpha decay (94%), Electron capture / beta-plus decay (6%) -22,453 keV 7,848 keV 4.26 × 10-15 eV
Re-163 — 390 ms Electron capture / beta-plus decay (68%), Alpha decay (32%) -26,002.25 keV 7,870.87 keV 1.17 × 10-15 eV
Re-164 — 0.70 s Alpha decay (58%), Electron capture / beta-plus decay (42%) -27,472.44 keV 7,881.05 keV 6.52 × 10-16 eV
Re-165 — 1.6 s Electron capture / beta-plus decay (86%), Alpha decay (14%) -30,659.35 keV 7,901.52 keV 2.85 × 10-16 eV
Re-166 — 2.25 s Electron capture / beta-plus decay (76%), Alpha decay (24%) -31,837.34 keV 7,909.64 keV 2.03 × 10-16 eV
Re-167 — 5.9 s Electron capture / beta-plus decay (99%), Alpha decay (1%) -34,834 keV 7,929 keV 7.73 × 10-17 eV
Re-168 — 4.4 s Electron capture / beta-plus decay (100%), Alpha decay (0.005%) -35,794.89 keV 7,935.12 keV 1.04 × 10-16 eV
Re-169 — 8.1 s Electron capture / beta-plus decay (100%), Alpha decay (0.01%) -38,409.25 keV 7,951.4 keV 5.63 × 10-17 eV
Re-170 — 9.2 s Electron capture / beta-plus decay (100%) -38,904 keV 7,955.01 keV 4.96 × 10-17 eV
Re-171 — 15.2 s Electron capture / beta-plus decay (100%) -41,250.29 keV 7,969.41 keV 3.00 × 10-17 eV
Re-172 — 15 s Electron capture / beta-plus decay (100%) -41,566.84 keV 7,971.85 keV 3.04 × 10-17 eV
Re-173 — 1.98 m Electron capture / beta-plus decay (100%) -43,553.87 keV 7,983.91 keV 3.84 × 10-18 eV
Re-174 — 2.40 m Electron capture / beta-plus decay (100%) -43,673.1 keV 7,985.09 keV 3.17 × 10-18 eV
Re-175 — 5.89 m Electron capture / beta-plus decay (100%) -45,288.31 keV 7,994.82 keV 1.29 × 10-18 eV
Re-176 — 5.3 m Electron capture / beta-plus decay (100%) -45,062.89 keV 7,993.97 keV 1.43 × 10-18 eV
Re-177 — 14 m Electron capture / beta-plus decay (100%) -46,269.18 keV 8,001.22 keV 5.43 × 10-19 eV
Re-178 — 13.2 m Electron capture / beta-plus decay (100%) -45,653.46 keV 7,998.16 keV 5.76 × 10-19 eV
Re-179 — 19.5 m Electron capture / beta-plus decay (100%) -46,584.31 keV 8,003.77 keV 3.90 × 10-19 eV
Re-180 — 2.46 m Electron capture / beta-plus decay (100%) -45,837.36 keV 7,999.99 keV 3.09 × 10-18 eV
Re-181 — 19.9 h Electron capture / beta-plus decay (100%) -46,517.41 keV 8,004.14 keV 6.37 × 10-21 eV
Re-182 — 64.2 h Electron capture / beta-plus decay (100%) -45,446.14 keV 7,998.63 keV 1.97 × 10-21 eV
Re-183 — 70.0 d Electron capture (100%) -45,809.66 keV 8,001.01 keV 7.54 × 10-23 eV
Re-184 — 35.4 d Electron capture / beta-plus decay (100%) -44,219.82 keV 7,992.75 keV 1.49 × 10-22 eV
Re-186 — 3.7185 d Beta-minus decay (92.5%), Electron capture (7.5%) -41,927.32 keV 7,981.27 keV 1.42 × 10-21 eV
Re-188 — 17.005 h Beta-minus decay (100%) -39,016.88 keV 7,966.75 keV 7.45 × 10-21 eV
Re-189 — 24.3 h Beta-minus decay (100%) -37,979.1 keV 7,961.81 keV 5.22 × 10-21 eV
Re-190 — 3.0 m Beta-minus decay (100%) -35,583.02 keV 7,949.78 keV 2.53 × 10-18 eV
Re-191 — 9.8 m Beta-minus decay (100%) -34,350.41 keV 7,943.96 keV 7.76 × 10-19 eV
Re-192 — 16 s Beta-minus decay (100%) -31,588.83 keV 7,930.24 keV 2.85 × 10-17 eV
Re-193 — — Unknown -30,231.64 keV 7,923.94 keV —
Re-194 — 5 s Beta-minus decay (100%) -27,260 keV 7,909 keV 9.12 × 10-17 eV
Re-195 — 6 s Beta-minus decay (100%) -25,560 keV 7,901 keV 7.60 × 10-17 eV
Re-196 — 3 s Beta-minus decay (100%) -22,360 keV 7,886 keV 1.52 × 10-16 eV
Re-197 — 160 ns Beta-minus decay -20,350 keV 7,877 keV 2.85 × 10-9 eV
Re-198 — 160 ns Beta-minus decay, Beta-minus, neutron emission -16,990 keV 7,861 keV 2.85 × 10-9 eV
Re-199 — 160 ns Beta-minus decay, Beta-minus, neutron emission -14,730 keV 7,850 keV 2.85 × 10-9 eV