Aluminum or Aluminium
Atomic Number: 13
Atomic Weight: 26.981539
Discovery: Hans Christian Oersted (1825, Denmark), Wohler (1827)
Electron Configuration: [Ne] 3s2 3p1
Word Origin: Latin alumen: alum, an astringent and dyeing mordant
Note on Naming: Sir Humphry Davy proposed the name aluminum for the metal, however, the name aluminium was adopted to conform with the "ium" ending of most elements. This spelling is in use in most countries. Aluminium was also the spelling in the U.S. until 1925, when the American Chemical Society officially decided to use the name aluminum instead.
Properties: Aluminum has a melting point of 660.37°C, boiling point of 2467°C, specific gravity of 2.6989 (20°C), and valence of 3. Pure aluminum is a silvery-white metal. It is soft, light, relatively nontoxic, with a high thermal conductivity, and high corrosion resistance. It can be easily formed, machined, or cast. Aluminum is nonmagnetic and nonsparking. It is second among metals in terms of malleability and sixth in ductility. Aluminum coatings are highly reflective of both visible and radiant heat. The coatings form a thin layer of protective oxide and do not deteriorate like silver coatings.
Uses: Ancient Greeks and Romans used alum as an astringent, for medicinal purposes, and as a mordant in dyeing. It is used in kitchen utensils, exterior decorations, and thousands of industrial applications. Although the electrical conductivity of aluminum is only about 60% that of copper per area of cross section, aluminum is used in electrical transmission lines because of its light weight. The alloys of aluminum are used in the construction of aircraft and rockets. Reflective aluminum coatings are used for telescope mirrors, making decorative paper, packaging, and many other uses. Alumina is used in glassmaking and refractories. Synthetic ruby and sapphire have applications in producing coherent light for lasers.
Sources: Aluminum is the most abundant metal in the Earth's crust (8.1%), although it is not found free in nature. In 1886, Hall in the United States and Heroult in France discovered how to obtain aluminum metal from electrolysis of alumina dissolved in cryolite. Cryolite is an aluminum ore, although it is has been replaced for commercial aluminum purification by an artificial mixture of sodium, aluminum, and calcium fluorides. The Bayer process is commonly used to refine the impure hydrated oxide ore, bauxite, for use in the Hall-Heroult refining process. Aluminum also can be produced from clay, although this is not the most economically feasible method at present. In addition to cryolite and bauxite, aluminum is found in feldspars, granite, and many other common minerals. The oxide, alumina, occurs naturally as ruby, sapphire, emery, and corundum.
Element Classification: Metal
Density (g/cc): 2.6989
Appearance: soft, lightweight, silvery-white metal
Isotopes: Aluminum has 23 known isotopes ranging from Al-21 to Al-43. Al-27 is the only stable isotope of aluminum. Al-26 is nearly stable with a half-life of 7.2 x 105 years.
Atomic Radius (pm): 143
Atomic Volume (cc/mol): 10.0
Covalent Radius (pm): 118
Ionic Radius: 51 (+3e)
Specific Heat (@20°C J/g mol): 0.900
Fusion Heat (kJ/mol): 10.75
Evaporation Heat (kJ/mol): 284.1
Debye Temperature (K): 394.00
Pauling Negativity Number: 1.61
First Ionizing Energy (kJ/mol): 577.2
Oxidation States: 3
Lattice Structure: Face-Centered Cubic
Lattice Constant (Å): 4.050
CAS Registry Number: 7429-90-5
- Aluminum was once called the "Metal of Kings" because pure aluminum was more expensive to produce than gold until the Hall-Heroult process was discovered.
- The primary source of aluminum is the ore bauxite.
- Aluminum is paramagnetic.
- The IUPAC adopted the name aluminium in 1990 and in 1993 recognized aluminum as an acceptable option for the element's name.