Aluminium, Physics

Aluminium

 

Atomic number

13

Symbol

Al

Atomic weight

26.98154

Discovery

Wohler 1827

Electronic configuration

[Ne] 3p'

Word origin

Latin alumen: alum, an astringent and dyeing mordant.

Melting point

660.370C

Atomic number

24670C

Symbol

2.6989

Electrical resistivity

2.8*10-8 ohm-m

Properties:

1.      Pure aluminium is a silvery-white metal.

2.      It is a soft, light, relatively non toxic, with a high thermal conductivity.

3.      It can be easily formed, machined, or cast.

4.      It is second among metals in terms of malleability and sixth in ductility. It can be put to a shape as per need by rolling, drawing, spinning and forging.

5.      Like copper, aluminium also forms an oxide layer over its surface when exposed to atmosphere and that layer prevents the materials from further oxidation and acts as a insulation because aluminium oxide has relatively higher resistivity. Thus, the contact resistance of aluminium wires is very high.

6.      It can be suitably alloyed with variety of other elements to cause an increase in strength and hardness.

7.      Aluminium coatings are highly reflective to both visible and radiant heat. The coatings form a thin layer of protecting oxide and do not deteriorate like silver coatings.

8.      It is nonmagnetic and nonspeaking.

Uses:

1.      Ancient Greeks and Romans used alum as and astringent for medical purposes and as a mordant in dyeing.

2.      It is used in kitchen utensils & exterior decorations.

3.      It is widely used as conductor for power transmission and distribution.

4.      It is also used in overhead transmission lines, bus bars, ASCR conductors etc.

5.      The alloys of aluminium are used in construction of aircraft and rockets.

6.      Reflective aluminium coatings are used for telescope mirrors, making decorative paper & packaging.

7.      Aluminium is used in glass making and refractories.

Sources: Aluminium is the most abundant metal in the earth crust (8.1%), although if it is not found free in nature. Cryolite is an aluminium ore, although it has been replaced for commercial aluminium purification by an artificial mixture of sodium, aluminium and cadmium fluorides. The Bayer process is commonly used to refine the impure hydrated oxide ore, bauxite, for use in the Hall-Heroult refining process. Aluminium also can be produced from clay, although this is not the most economically feasible method at present. In addition to Cryolite and bauxite, aluminium is found in feldspars, granite, and many other common minerals. Two oxide, alumina, occurs naturally as ruby. Sapphire, emery and corundum.

Posted Date: 7/21/2012 7:44:56 AM | Location : United States







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