Rhenium - Periodic Table of Videos

Rhenium is a chemical element with symbol Re and atomic number 75. It is a silvery-white, heavy, third-row transition metal in group 7 of the periodic table. With an estimated average concentration of 1 part per billion (ppb), rhenium is one of the rarest elements in the Earth's crust. The free element has the third-highest melting point and highest boiling point of any element, at 5,869 K (10,105 °F). Rhenium resembles manganese and technetium chemically and is obtained as a by-product of molybdenum and copper ore's extraction and refinement. Rhenium shows in its compounds a wide variety of oxidation states ranging from −1 to +7.
Discovered in 1925, rhenium was the last stable element to be discovered. It was named after the river Rhine in Europe.
Nickel-based superalloys of rhenium are used in the combustion chambers, turbine blades, and exhaust nozzles of jet engines. These alloys contain up to 6% rhenium, making jet engine construction the largest single use for the element, with the chemical industry's catalytic uses being next-most important. Because of the low availability relative to demand, rhenium is among the most expensive of metals, with an average price of approximately US$2,750 per kilogram (US$85.53 per troy ounce) as of April 2015; it is also of critical strategic military importance, for its use in high performance military jet and rocket engines.^[3]
Rhenium is a silvery-white metal with one of the highest melting points of all elements, exceeded by only tungsten and carbon. It also has the highest boiling point of all elements. It is also one of the densest, exceeded only by platinum, iridium and osmium. Rhenium has a hexagonal close-packed crystal structure, with lattice parameters a = 276.1 pm and c = 445.6 pm.^[12]
Its usual commercial form is a powder, but this element can be consolidated by pressing and sintering in a vacuum or hydrogen atmosphere. This procedure yields a compact solid having a density above 90% of the density of the metal. When annealed this metal is very ductile and can be bent, coiled, or rolled.^[13] Rhenium-molybdenum alloys are superconductive at 10 K; tungsten-rhenium alloys are also superconductive^[14] around 4–8 K, depending on the alloy. Rhenium metal superconducts at 1.697 ± 0.006 K.^{[15] [16]}
In bulk form and at room temperature and atmospheric pressure, the element resists alkalis, sulfuric acid, hydrochloric acid, dilute (but not concentrated) nitric acid, and aqua regia.