Review
Aluminium
Content
1. Introduction
2.Characteristics
3. Isotopes
4. Naturaloccurrence
5. Productionand refinement
6. Recycling
7. Chemistry
7.1 Oxidationstate +1
7.2 Oxidationstate +2
7.3 Oxidationstate +3
7.4 Analysis
8.Applications
8.1 Generaluse
8.2 Aluminiumcompounds
8.3 Aluminiumalloys in structural applications
8.4 Householdwiring
9. History
10. Etymology
10.1Nomenclature history
10.2Present-day spelling
11. Healthconcerns
12. Effect onplants
13. Conclusion
14. References
1.Introduction
Aluminiumis a silvery white and ductile member of the boron group of chemical elements.It has the symbol Al; its atomic number is 13. It is not soluble in water undernormal circumstances. Aluminium is the most abundant metal in the Earth'scrust, and the third most abundant element therein, after oxygen and silicon.It makes up about 8% by weight of the Earth's solid surface. Aluminium is tooreactive chemically to occur in nature as a free metal. Instead, it is foundcombined in over 270 different minerals. [4] The chief source of aluminium isbauxite ore.
Aluminiumis remarkable for its ability to resist corrosion due to the phenomenon ofpassivation and for the metal's low density. Structural components made fromaluminium and its alloys are vital to the aerospace industry and very importantin other areas of transportation and building. Its reactive nature makes ituseful as a catalyst or additive in chemical mixtures, including being used inammonium nitrate explosives to enhance blast power.
Generalproperties
Name,symbol, number aluminium, Al, 13
Elementcategory other metal
Group,period, block 13, 3, p
Standardatomic weight 26.9815386 (13) g В· mol-1
Electronconfiguration [Ne] 3s2 3p1
Electronsper shell 2, 8, 3 (Image)
Physicalproperties
Phasesolid
Density(Near r.t.) 2.70 g В· cm-3
Liquiddensity at m.p. 2.375 g В· cm-3
Meltingpoint 933.47 K, 660.32 В° C, 1220.58 В° F
Boilingpoint 2792 K, 2519 В° C, 4566 В° F
Heatof fusion 10.71 kJ В· mol-1
Heatof vaporization 294.0 kJ В· mol-1
Specificheat capacity (25 В° C) 24.200 J В· mol-1 В· K-1
Vaporpressure
P/Pa1 жовтня 100 1 k 10 k 100 k
atT/K 1482 1632 1817 2054 2364 2790
Atomicproperties
Oxidationstates 3, 2 [1], [1] 2
(amphotericoxide)
Electronegativity1.61 (Pauling scale)
Ionizationenergies
(more)1st: 577.5 kJ В· mol-1
2nd:1816.7 kJ В· mol-1
3rd:2744.8 kJ В· mol-1
Atomicradius 143 pm
Covalentradius 121 В± 4 pm
Vander Waals radius 184 pm
Miscellanea
Crystalstructure face-centered cubic
Magneticordering paramagnetic [3]
Electricalresistivity (20 В° C) 28.2 nО© В· m
Thermalconductivity (300 K) 237 W В· m-1 В· K-1
Thermalexpansion (25 В° C) 23.1 Ојm В· m-1 В· K-1
Speedof sound (thin rod) (rt) (rolled) 5,000 m В· s-1
Young'smodulus 70 GPa
Shearmodulus 26 GPa
Bulkmodulus 76 GPa
Poissonratio 0.35
Mohshardness 2.75
Vickershardness 167 MPa
Brinellhardness 245 MPa
CASregistry number 7429-90-5
2.Characteristics
Aluminiumis a soft, durable, lightweight, malleable metal with appearance ranging fromsilvery to dull grey, depending on the surface roughness. Aluminium is nonmagneticand nonsparking. It is also insoluble in alcohol, though it can be soluble inwater in certain forms. The yield strength of pure aluminium is 7-11 MPa, whilealuminium alloys have yield strengths ranging from 200 MPa to 600 MPa. [5]Aluminium has about one-third the density and stiffness of steel. It isductile, and easily machined, cast, drawn and extruded.
Corrosionresistance can be excellent due to a thin surface layer of aluminium oxide thatforms when the metal is exposed to air, effectively preventing furtheroxidation. The strongest aluminium alloys are less corrosion resistant due togalvanic reactions with alloyed copper. [5] This corrosion resistance is alsooften greatly reduced when many aqueous salts are present however, particularlyin the presence of dissimilar metals.
Aluminiumatoms are arranged in a face-centred cubic (fcc) structure. Aluminium has astacking-fault energy of approximately 200 mJ/mВІ. [6]
Aluminiumis one of the few metals that retain full silvery reflectance in finelypowdered form, making it an important component of silver paints. Aluminiummirror finish has the highest reflectance of any metal in the 200-400 nm (UV)and the 3000-10000 nm (far IR) regions, while in the 400-700 nm visible rangeit is slightly outdone by tin and silver and in the 700-3000 (near IR) bysilver, gold, and copper. [7]
Aluminiumis a good thermal and electrical conductor, by weight better than copper.Aluminium is capable of being a superconductor, with a superconducting criticaltemperature of 1.2 kelvin and a critical magnetic field of about 100 gauss. [8]
3.Isotopes
Aluminiumhas nine isotopes, whose mass numbers range from 23 to 30. Only 27Al (stableisotope) and 26Al (radioactive isotope, t1/2 = 7.2 Г— 105 y) occurnaturally; however, 27Al has a natural abundance of 99.9 +%. 26Al is producedfrom argon in the atmosphere by spallation caused by cosmic-ray protons.Aluminium isotopes have found practical application in dating marine sediments,manganese nodules, glacial ice, quartz in rock exposures, and meteorites. Theratio of 26Al to 10Be has been used to study the role of transport, deposition,sediment storage, burial times, and erosion on 105 to 106 year time scales. [9]Cosmogenic 26Al was first applied in studies of the Moon and meteorites.Meteoroid fragments, after departure from their parent bodies, are exposed tointense cosmic-ray bombardment during their travel through space, causingsubstantial 26Al production. After falling to Earth, atmospheric shieldingprotects the meteorite fragments from further 26Al production, and its decaycan then be used to determine the meteorite's terrestrial age. Meteoriteresearch has also shown that 26Al was relatively abundant at the time offormation of our planetary system. Most meteorite scientists believe that theenergy released by the decay of 26Al was responsible for the melting anddifferentiation of some asteroids after their formation 4.55 billion yearsago. [10]
4.Natural occurrence
Inthe Earth's crust, aluminium is the most abundant (8.3% by weight) metallicelement and the third most abundant of all elements (after oxygen andsilicon). [11] Because of its strong affinity to oxygen, however, it is almostnever found in the elemental state; instead it is found in oxides or silicates.Feldspars, the most common group of minerals in the Earth's crust, arealuminosilicates. Native aluminium metal can be found as a minor phase in lowoxygen fugacity environments, such as the interiors of certain volcanoes. [12]It also occurs in the minerals beryl, cryolite, garnet, spinel andturquoise. [11] Impurities in Al2O3, such as chromium or cobalt yield thegemstones ruby ​​and sapphire, respectively. Pure Al2O3, known as Corundum, is oneof the hardest materials known. [11]
Althoughaluminium is an extremely common and widespread element, the common aluminiumminerals are not economic sources of the metal. Almost all metallic aluminiumis produced from the ore bauxite (AlOx (OH) 3-2x). Bauxite occurs as a weatheringproduct of low iron and silica bedro...
