Aluminum

Aluminum - Al

CAS: 7429-90-5
Description: Silvery, light weight, non-magnetic, non-sparking, malleable metal
Classification: Other Metals
Date of Discovery: 1825
Discoverer: Hans Christian Oersted
Alternative Spelling: Aluminium
Name Origin: Latin alumen, "alum"

Atomic Number: 13
Number of Neutrons: 14
Atomic Mass: 26.981539(5) amu
Melting Point: 660.323 °C
Boiling Point: 2519 °C
Density (293 K): 2.6989 g/cm³
Atomic volume: 10.0 cm³/mol
Electrical resistivity: 0.377 10^-6/cm

Thermal conductivity: 2.37 W/cmK
Enthalpy of atomization: 322.17 kJ/mol
Enthalpy of vaporization: 293.40 kJ/mol
Enthalpy of fusion: 10.790 kJ/mol
Specific heat capacity: 0.90 J/gK

Energy levels: 2-8-3
Electron configuration: [Ne]3s²3p¹
Crystal Structure: Cubic face centered
Atomic radius: 1.82 Å
Covalent radius: 1.18 Å
Oxidation States: +3
Electronegativity, Pauling: 1.61
Electron affinity: 0.441 eV
First ionization energy: 5.986 eV
2nd ionization energy: 18.828 eV
3rd ionization energy: 28.447 eV
Polarizability: 6.8 10^-24cm³

Isotope	Natural Abundance	Atomic Mass	Half-life	Decay Mode	Spin
²²Al	22.0195	70 ms	⁺; ⁺, p	4+
²³Al	23.00727	0.47 s	⁺; ⁺, p
^24mAl	0.129 s	IT; ^-	1+
²⁴Al	23.999941	2.07 s	⁺, p	4+
²⁵Al	24.990429	7.17 s	⁺	5/2+
^26mAl	6.345 s	⁺	0+
²⁶Al	25.9868917	7.1 x 10⁵ y	⁺; EC	5+
²⁷Al	100.	26.9815384	Stable	5/2+
²⁸Al	27.9819102	2.25 m	^-	3+
²⁹Al	28.980445	6.5 m	^-	5/2+
³⁰Al	29.98296	3.68 s	^-	3+
³¹Al	30.98395	0.64 s	^-
³²Al	31.9881	33 ms	^-	1+
³³Al	32.9909
³⁴Al	33.9969	0.05 s
³⁵Al	34.9999	^-
³⁶Al	36.0064
The ancient Greeks and Romans used alum in medicine as an astringent and as a mordant in dyeing. In 1761 de Morveau proposed the name alumine for the base in alum, and Lavoisier, in 1787, thought this to be the oxide of a still undiscovered metal. Wohler is generally credited with having isolated the metal in 1827, although an impure form was prepared by Oersted two years earlier. In 1807, Davy proposed the name alumium for the metal, undiscovered at that time, and later agreed to chance it to aluminum. Shortly thereafter, the name aluminium was adopted to conform with the "ium" ending of most elements, and this spelling is now in use elsewhere in the world. Aluminium was also the accepted spelling in the U.S. until 1925, at which time the American Chemical Society officially decided to use the name aluminum thereafter in their publications. The method of obtaining aluminum metal by the electrolysis of alumina dissolved in cryolite was discovered in 1886 by Hall in the U.S. and at about the same time by Heroult in France. Cryolite (Na₃AlF₆), a natural ore found in Greenland, is no longer widely used in commercial production, but has been replaced by an artificial mixture of sodium, aluminum, and calcium fluorides. Bauxite, an impure hydrated oxide ore, is found in large deposits in Jamaica, Australia, Surinam, Guyana, Arkansas, and elsewhere. Bauxite is composed of aluminum oxide and hydroxide minerals such as gibbsite Al(OH)₃, boehmite, AlO(OH) and diaspore, HAlO₂, as well as clays, silt and iron oxides and hydroxides. The Bayer process is most commonly used today to refine bauxite so it can be accommodated in the Hall-Heroult refining process, used to make most aluminum. Aluminum can now be produced from clay, but the process is not economically feasible at present. Aluminum is the most abundant metal to be found in the earth's crust (8.1%), but is never found free in nature. In addition to the minerals mentioned above, it is found in feldspars, granite, and in many other common minerals. Seventeen isotopes and isomers are known. Natural aluminum is made of one isotope, ²⁷Al. Pure aluminum, a silvery-white metal, possesses many desirable characteristics. It is light, nontoxic, has a pleasing appearance, can easily be formed, machined, or cast, has a high thermal conductivity, and has excellent corrosion resistance. It is nonmagnetic and nonsparking, stands second among metals in the scale of malleability, and sixth in ductility. It is extensively used for kitchen utensils, outside building decoration, and in thousands of industrial applications where a strong, light, easily constructed material is needed. Although its electrical conductivity is only about 60% that of copper, it is used in electrical transmission lines because of its light weight. Pure aluminum is soft and lacks strength, but it can be alloyed with small amounts of copper, magnesium, silicon, manganese and other elements to impart a variety of useful properties. These alloys are of vital importance in the construction of modern aircraft and rockets. Aluminum, evaporated in a vacuum, forms a highly reflective coating for both visible light and radiant heat. These coatings soon form a thin layer of the protective oxide and do not deteriorate as do silver coatings. They have found application in coatings for telescope mirrors, in making decorative paper, packages, toys, and in many other uses. The compounds of greatest importance are aluminum oxide, the sulfate, and the soluble sulfate with potassium (alum). The oxide, alumina (Al₂O₃), occurs naturally as ruby, sapphire, corundum, and emery, and is used in glassmaking and refractories. Synthetic ruby and sapphire have found application in the construction of lasers for producing coherent light. LINKS: The Aluminum Association, Inc. Aluminum Can Recycling Aluminum Chemistry Aluminum, Drinking Water, and Alzheimer's Disease Aluminum Wiring in Residential Properties: Hazards & Remedies Welcome to the world of Aluminum and Alcoa Return Sources for the information on this website include: Lide, David R., ed. CRC Handbook of Chemistry and Physics, 78th Ed., 1997-1998.

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