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Rhenium

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Rhenium
Rhenium
General Info
Atomic Symbol Atomic symbol::Re
Atomic Number Atomic number::75
Atomic Weight Atomic weight::186.2 g/mol
Chemical series Transition metals
Appearance  ?
Rhenium.jpg
Group, Period, Block 7,6,d.
Electron configuration [Xe] 4f14, 5d5, 6s2
Electrons per shell
Electron shell rhenium.png
CAS number CAS number::7440-15-5
Physical properties
Phase Solid
Density Density::20.5 g/ml
Melting point Melting point::3170 °C
Boiling point Boiling point::5627 °C
Isotopes of Rhenium
iso NA half-life DT DE (MeV) DP

9

185Re 37.4% 185Re is stable with 110 neutrons.
187Re 62.6% 4.35x1010 y α (not observed) 1.653 183Ta
187Re 62.6% 4.35x1010 y β- 0.0026 187Os
All properties are for STP unless otherwise stated.

Rhenium is a chemical element that is classified as a transition metal and known by the chemical symbol Re. It is one the rarest elements in the world and is found naturally in the earth's crust. The majority of rhenium is imported from other countries like Chile and Germany since it is difficult to find large amounts of the element. This element is used in everything from electrical components to flash igniters in cameras to rocket thrusters in small satellites. The melting point of rhenium is one of the highest of all elements and it has an extremely high density. Rhenium has high electrical resistance and is fairly reactive with strong acids and other elements. Overall, rhenium is one of the most unique elements in existence and is full of unusual properties that can be useful to the world.

Properties

Rhenium has a silvery white look with a metallic luster accompanied by an extremely high density of 21.04g/cm3. Rhenium can be shaped through rolling and bending and will stay ductile until it reaches its melting point. This element also has a high recrystallisation temperature of 2800°C allowing it to have creep resistance. The melting point of Rhenium is 3180°C(only below carbon and tungsten)and has high electrical resistance over a wide variety of temperatures.Rhenium does not form carbides and has a high modulus of elasticity[1]. Rhenium does not react with oxygen and other acids readily but strong acids react like nitric acid (HNO3)and sulfuric acid (H2SO4)[2]. Rhenium can withstand a large amount of thermal cycling without deterioration along with a great and high temperature strength.

Occurrences

Rhenium is not a naturally found and is located within the earth's crust approximately 0.001 ppm. Commercial Rhenium used is taken from molybdenum roaster-flue dusts from copper-sulfide ores. About a third of the rhenium used in the United States are taken from molybdenum and copper ores while the other two thirds are extracted and imported from countries like Germany, Chile, and the UK. After it is extracted, the metal is prepared by reducing ammonium perrhenate with hydrogen at high temperatures. Rhenium is one of the most rare elements of the planet and one of the hardest to acquire for commercial use[3]

Uses

The largest primary use of Rhenium in the world currently is in superalloys that manufacture high temperature turbine engine components; this accounting for 70% of the Rhenium supply in 2009. Rhenium's second most common usage is in catalytic reforming of Petroleum to produce high-octane unleaded gasoline.

Rhenium also has secondary uses by using its alloys to make up electron tubes and targets,and temperature controls.

Laboratory uses of Rhenium consist of catalysis reactions in organic chemistry laboratories to modify hydrocarbons along with other organic compounds[4].When added to tungsten and molybdenum alloys it can be used in refractory metal components of missiles, electrical contacts, oven filaments, igniters for flash bulbs, jewelry, and plating of metals through electrolysis and vapor-phase deposition[5]. Rhenium can be used in rocket thrusters for small satellites,thermistors,and after being made radioactive through neutron bombardment it can be used for medical applications to treat restenosis (narrowing of a blood vessel) and liver tumors. In catalysts it is used for hydrogenation of fine chemicals, hydrocracking, reforming and disproportionating olefins. Rhenium is perfect for this job since it has a great resistance to poisoning from other elements like nitrogen and sulfur[6].

Compounds

Rhenium has many common compounds that are split into groups of fluorides, chlorides, bromides, iodides, oxides, sulfides, tellurides, and carbonyls and are listed below.

Fluorides

  • Rhenium hexafluoride: ReF6
  • Rhenium tetrafluoride: ReF4
  • Rhenium pentafluoride: ReF5
  • Rhenium heptafluoride: ReF7

Chlorides

  • Rhenium hexachloride: ReCl6
  • Rhenium tetrachloride: ReCl4
  • Rhenium pentachloride: ReCl5
  • Trirhenium nonachloride: [ReCl3]3

Bromides

  • Rhenium tetrabromide: ReBr4
  • Rhenium pentabromide: ReBr5
  • Trirhenium nonabromide: [ReBr3]3

Iodides

  • Rhenium tetraiodide: ReI4
  • Trirhenium nonaiodide: [ReI3]3

Oxides

  • Rhenium dioxide: ReO2
  • Rhenium trioxide: ReO3
  • Dirhenium trioxide: Re2O3
  • Dirhenium heptoxide: Re2O7

Sulfides

  • Rhenium disulphide: ReS2
  • Dirhenium heptasulphide: Re2S7

Tellurides

  • Rhenium ditelluride: ReTe2

Carbonyls

  • Dirhenium decacarbonyl: Re2(CO)10[7]

References

Additional Information

  • [1] Vincent Summers, eHow.com, updated August 24th,2009