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Friday, December 1, 2006

Rhenium







Nextel ringtones Tungsten - '''Rhenium''' - Abbey Diaz Osmium

Free ringtones Technetium/Tc
'''Re'''Majo Mills Bohrium/Bh  
Mosquito ringtone Image:Re-TableImage-BIG.png/250px/
Sabrina Martins Periodic table (standard)/Full table



'''General'''

Nextel ringtones List of elements by name/Name, Abbey Diaz List of elements by symbol/Symbol, Free ringtones List of elements by number/NumberRhenium, Re, 75

Majo Mills Chemical seriesCingular Ringtones transition metals

glamour is periodic table group/Group, as lawrence periodic table period/Period, carolina line periodic table block/Blocktop tribute group 7 element/7 (VIIB), afternoon headline period 6 element/6, agra the d-block/d

courts find Density, an unacceptable Mohs hardness scale/Hardness21020 me you kilogram per cubic metre/kg/m3, 7

yet do color/Appearancegrayish whiteprovide hilarity Image:Re,75.jpg/125px/

'''Atomic properties'''

cupola weathered Atomic weight186.207 can jump Atomic mass unit/amu

airtight yet Atomic radius (calc.)135 (188) erased he picometre/pm

poll its Covalent radius159 pm

surcharge it van der Waals radiusno data

express world Electron configurationsoap operas [xenon/Xe]4for montemayor f-orbital/f145d56s-orbital/s2

electron/e-'s per energy level2, 8, 18, 32, 13, 2

Oxidation states (Oxide)'''6''', 4, 2, -2 (mildly acidic)

Crystal structureHexagonal

'''Physical Properties'''
State of mattersolid (magnetism/__)

Melting point3459 Kelvin/K (5767 °Fahrenheit/F)

Boiling point5869 K (10105 °F)

Molar volume8.86 scientific notation/×10-6 cubic metre per mole/m3/mol

Heat of vaporization715 kilojoule per mole/kJ/mol

Heat of fusion33.2 kJ/mol

Vapor pressure3.24 Pascal/Pa at 3453 K

Speed of sound4700 metre per second/m/s at 293.15 K

'''Miscellaneous'''

Electronegativity1.9 (Pauling scale)

Specific heat capacity137 joule per kilogram-kelvin/J/(kg*K)

Electrical conductivity5.42 106/m ohm

Thermal conductivity47.9 watt per metre-kelvin/W/(m*K)

1st ionization potential760 kJ/mol

2nd ionization potential1260 kJ/mol

3rd ionization potential2510 kJ/mol

4th ionization potential3640 kJ/mol

'''Most stable isotopes'''




Isotope/isonatural abundance/NAhalf-life decay mode/DMdecay energy/DE mega/Melectron volt/eVdecay product/DP

185Re37.4%Re is stable isotope/stable with 110 neutrons

meta state/Metasynthetic radioisotope/2 E5 year/ybeta decay/β-isomeric transition/IT
0.2180.149osmium/186Os 

187Re'''62.6%'''4.35 E10 yalpha decay/αβ1.6530.003tantalum/183Taosmium/187Os



SI units & standard temperature and pressure/STP are used except where noted.


'''Rhenium''' is a chemical element in the periodic table that has the symbol '''Re''' and atomic number 75. A silvery-white, rare, heavy, polyvalent transition metal, rhenium resembles manganese chemically and is used in some alloys. Rhenium is obtained as a by-product of molybdenum refinement and rhenium-molybdenum alloys are superconducting. This was the last naturally-occurring element to be discovered

Notable characteristics
Rhenium is a silvery white metal, lustrous, and has one of the highest melting points of all elements, exceeded by only tungsten and carbon. It is also one of the most dense, exceeded only by platinum, iridium, and osmium. The oxidation states of rhenium include -1,+1,+2,+3,+4,+5,+6 and +7 oxidation states. The oxidation states +7,+6,+4,+2 and -1 are the most common.

Its usual commercial form is a powder, but this element can be consolidated by pressing and resistance-sintering in a vacuum or hydrogen atmosphere. This procedure yields a compact shape that is in excess of 90 percent of the density of the metal. When annealed this metal is very ductile and can be bent, coiled, or rolled. Rhenium-molybdenum alloys are superconductivity/superconductive at 10 Kelvin/K.

Applications
This element is used in platinum-rhenium catalysts which in turn are primarily used in making lead-free, high-octane gasoline and in high-temperature superalloys that are used to make jet engine parts. Other uses:

* Widely used as filaments in mass spectrographs and in ion gauges.
* An additive to tungsten and molybdenum-based alloys to give them useful properties.
* Rhenium catalysts are very resistant to chemical poisoning, and so are used in certain kinds of hydrogenation reactions.
* Electrical contact material due to its good wear resistance and ability to withstand arc corrosion.
* Thermocouples containing alloys of rhenium and tungsten are used to measure temperatures up to 2200 °Celsius/C.
* Rhenium wire is used in photoflash lamps in photography.

History
Rhenium (Latin ''Rhenus'' meaning "Rhine") was the last naturally-occurring element to be discovered. It is generally considered to be discovered by Walter Noddack, Ida Tacke, and Otto Berg in Germany. In 1925 they reported that they detected the element in platinum ore and in the mineral columbite. They also found rhenium in gadolinite and molybdenite. In 1928 they were able to extract 1 g of element by processing 660 kilogram/kg of molybdenite.

The process was so complicated and the cost so high that production was discontinued until early 1950 when tungsten-rhenium and molybdenum-rhenium alloys were prepared. These alloys found important applications in industry that resulted in a great demand for the rhenium produced from the molybdenite fraction of porphyry copper ores.

Occurrence
Rhenium is not naturally found free in nature or even as a compound in a distinct mineral species. This element is widely spread through the earth's crust at approximately 0.001 part per million/ppm. Commercial rhenium is extracted from molybdenum roaster-flue dusts from copper-sulfide ores. Some molybdenum ores contain 0.002% to 0.2% rhenium. The metal form is prepared by reducing ammonium perrhentate with hydrogen at high temperatures.

Isotopes
Naturally occurring rhenium is a mix of one stable isotope and one radioactive isotope with a very long half-life. There are twenty six other unstable isotopes recognized.

Precautions
Little is known about rhenium toxicity so it should be handled with care.

References
*http://periodic.lanl.gov/elements/75.html

External links
*http://www.webelements.com/webelements/elements/text/Re/index.html
*http://environmentalchemistry.com/yogi/periodic/Re.html
Tag: Chemical elements
Tag: Transition metals

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