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| Atomic symbol: Re |
| Atomic number: 75 |
| Atomic weight: 186.207 |
| Atomic volume: 8.85 cm3/mol |
| Density: 21.0 g/cm3 |
| Period Number: 6 |
| Group number: 7 |
| Group name: Trans. Met. |
| Element classification: Metal |
| Phase at room temperature: Solid |
| Melting Point: 3453.2 K |
| Boiling point: 5923 K |
| Heat of fusion: 33.20 kJ/mol |
| Heat of vaporization: 715.0 kJ/mol |
| Ionization Energy: 7.88 eV |
| 1st ionization energy: 760 kJ/mole |
| 2nd ionization energy: kJ/mole |
| 3rd ionization energy: kJ/mole |
| Electronegativity: 1.9 |
| Electron affinity: 14 kJ/mole |
| Specific heat: 0.13 J/gK |
| Heat atomization: 770 kJ/mole atoms |
| Shells: 2,8,18,32,13,2 |
| Electron Shell Configuration: [Xe] 4f14 5d5 6s2 |
| Minimum oxidation number: -3 |
| Maximum oxidation number: 7 |
| Minimum common oxidation number: 0 |
| Maximum common oxidation no: 4 |
Appearance & Characteristics |
| Structure:: hcp: hexagonal close pkd |
| Color: silvery-white |
| Hardness: mohs |
| Toxicity: ? |
| Characteristics: high melting point |
| Uses: catalysts, thermocouples |
| Reaction with air: mild, w/ht =>Re2O7 |
| Reaction with 6M HCl: none |
| Reaction with 15M HNO3: mild, =>HReO4 |
| Reaction with 6M NaOH: ? |
| Number of isotopes: 2 |
| Oxide(s): Re2O5 ReO3 Re2O7 |
| Hydride(s): none |
| Chloride(s): Re3Cl9 ReCl4 ReCl5 ReCl6 |
| Atomic Radius: 137 pm |
| Ionic radius (1- ion): pm |
| Ionic radius (1+ ion): pm |
| Ionic radius (2- ion): pm |
| Ionic radius (2+ ion): pm |
| Ionic radius (3+ ion): pm |
| Thermal conductivity: 48 J/m-sec-deg |
| Electrical conductivity: 51.813 1/mohm-cm |
| Polarizability: 9.7 A^3 |
| Source: Molybdenite (sulfide) |
| Relative abundance solar system: -1.287 log |
| Abundance earth's crust: -2.3 log |
| Estimated crustal abundance: 7×10-4 milligrams per kilogram |
| Estimated oceanic abundance: 4×10-6 milligrams per liter |
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| (L. Rhenus: Rhine) Discovery of rhenium is generally attributed to Noddack, Tacke, and Berg, who announced in 1925 they had detected the element in platinum ore and columbite. They also found the element in gadolinite and molybdenite. By working up 660 kg of molybdenite in 1928 they were able to extract 1 g of rhenium. |
Rhenium does not occur free in nature or as a compound in a distinct mineral species. It is, however, widely spread throughout the earth's crust to the extent of about 0.001 ppm. Commercial rhenium in the U.S. today is obtained from molybdenum roaster-flue dusts obtained from copper-sulfide ores mined in the vicinity of Miami, Arizona and elsewhere in Arizona and in Utah.
Some molybdenum contains from 0.002% to 0.2% rhenium. More than 150,000 troy ounces of rhenium are now being produced yearly in the United States. The total estimated Free World reserve of rhenium metal is 3500 tons. Rhenium metal is prepared by reducing ammonium perrhentate with hydrogen at elevated temperatures.
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The element is silvery white with a metallic luster; its density is exceeded only by that of platinum , iridium, and osmium, and its melting point is exceeded only by that of tungsten and carbon .
The usual commercial form of the element is powder, but it can be consolidated by pressing and resistance-sintering in a vacuum or hydrogen atmosphere. This process produces a compact shape in excess of 90 percent of the density of the metal.
Annealed rhenium is very ductile, and can be bent, coiled, or rolled. Rhenium is used as an additive to tungsten and molybdenum -based alloys to impart useful properties.
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It is widely used as filaments for mass spectrographs and ion gauges. Rhenium-molybdenum alloys are superconductive at 10 K.
Rhenium is also used as an electrical contact material because it has good wear resistance and withstands arc corrosion. Thermocouples made of Re-W are used for measuring temperatures up to 2200C, and rhenium wire is used in photoflash lamps for photography.
Rhenium catalysts are exceptionally resistant to poisoning from nitrogen , sulfur , and phosphorus , and are used for hydrogenation of fine chemicals.
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| Natural rhenium is a mixture of two stable isotopes. Twenty six other unstable isotopes are recognized. |
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