Aluminum
| Atomic Number: | 13 |
| Symbol: | Al |
| Atomic Weight: | 26.98154 |
| Discovery: | Wohler 1827 |
| Electron Configuration: | [Ne]3p1 |
| Word Origin: | Latin alumen: alum, an astringent and dyeing mordant |
| 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. |
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