Aluminium

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Aluminium,  13Al
Aluminium-4.jpg
General properties
Pronunciation
Alternative namealuminum (U.S., Canada)
Appearancesilvery gray metallic
Standard atomic weight (Ar, standard)26.9815384(3)[1]
Aluminium in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
B

Al

Ga
magnesiumaluminiumsilicon
Atomic number (Z)13
Groupgroup 13 (boron group)
Periodperiod 3
Blockp-block
Element category  post-transition metal, sometimes considered a metalloid
Electron configuration[Ne] 3s2 3p1
Electrons per shell
2, 8, 3
Physical properties
Phase at STPsolid
Melting point933.47 K ​(660.32 °C, ​1220.58 °F)
Boiling point2743 K ​(2470 °C, ​4478 °F)
Density (near r.t.)2.70 g/cm3
when liquid (at m.p.)2.375 g/cm3
Heat of fusion10.71 kJ/mol
Heat of vaporization284 kJ/mol
Molar heat capacity24.20 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 1482 1632 1817 2054 2364 2790
Atomic properties
Oxidation states−2, −1, +1,[2] +2,[3] +3 (an amphoteric oxide)
ElectronegativityPauling scale: 1.61
Ionization energies
  • 1st: 577.5 kJ/mol
  • 2nd: 1816.7 kJ/mol
  • 3rd: 2744.8 kJ/mol
  • (more)
Atomic radiusempirical: 143 pm
Covalent radius121±4 pm
Van der Waals radius184 pm
Color lines in a spectral range
Spectral lines of aluminium
Other properties
Natural occurrenceprimordial
Crystal structureface-centered cubic (fcc)
Face-centered cubic crystal structure for aluminium
Speed of sound thin rod(rolled) 5000 m/s (at r.t.)
Thermal expansion23.1 µm/(m·K) (at 25 °C)
Thermal conductivity237 W/(m·K)
Electrical resistivity26.5 nΩ·m (at 20 °C)
Magnetic orderingparamagnetic[4]
Magnetic susceptibility+16.5·10−6 cm3/mol
Young's modulus70 GPa
Shear modulus26 GPa
Bulk modulus76 GPa
Poisson ratio0.35
Mohs hardness2.75
Vickers hardness160–350 MPa
Brinell hardness160–550 MPa
CAS Number7429-90-5
History
Namingafter alumina (aluminium oxide), itself named after mineral alum
PredictionAntoine Lavoisier (1782)
Discovery and first isolationHans Christian Ørsted (1824)
Named byHumphry Davy (1812)
Main isotopes of aluminium
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
26Al trace 7.17×105 y β+ 26Mg
ε 26Mg
γ
27Al 100% stable
| references

Aluminium (in American English also: aluminum) is a chemical element. The symbol for aluminium is Al, and its atomic number is 13. Aluminium is the most abundant metal.

Properties[change | change source]

Aluminium is a very good conductor of electricity and heat. It is light and strong. It can be hammered into sheets (malleable) or pulled out into wires (ductile). It is a highly reactive metal, although it is corrosion resistant.

Aluminium prevents corrosion by forming a small, thin layer of aluminium oxide on its surface. This layer protects the metal by preventing oxygen from reaching it. Corrosion can not occur without oxygen. Because of this thin layer, the reactivity of aluminium is not seen. As a powder it burns hot. Uses include fireworks displays and rocket fuel.

Occurrence and preparation[change | change source]

Pure aluminium is made from bauxite, a kind of rock that has aluminium oxide and many impurities. The bauxite is crushed and reacted with sodium hydroxide. The aluminium oxide dissolves. Then the aluminium oxide is dissolved in liquid cryolite, a rare mineral. Cryolite is normally produced artificially though. The aluminium oxide is electrolyzed to make aluminium and oxygen.

Aluminium was once considered a precious metal that was even more valuable than gold. This is no longer true because, as technology improved, it became cheaper and easier to make pure metal.

Compounds[change | change source]

Aluminium forms chemical compounds in the +3 oxidation state. They are generally unreactive. Aluminium chloride and aluminium oxide examples. Very rarely are compounds in the +1 or +2 oxidation state.

Uses[change | change source]

Many things are made of aluminum. Much of it is used in overhead power lines. It is also widely used in window frames and aircraft bodies. It is found at home as saucepans, soft drink cans, and cooking foil. Aluminium is also used to coat car headlamps and compact discs.

Pure aluminium is very soft, so a harder metal is almost always added. The harder metal is usually copper. Copper/aluminium alloys are to make ships, because the aluminium prevents corrosion, and the copper prevents barnacles.

Aluminium compounds are used in deodorants, water processing plants, food additives, and antacids.

Recycling[change | change source]

Since aluminium needs to be made by electrolysis, it requires a very large amount of electrical power. Recycling aluminium would be much cheaper. That's why recycling plants were opened. The cost of recycling aluminium is much less than the cost of making it from bauxite.

Toxicity[change | change source]

Aluminium is not used in the human body, although it is very common. People debate whether its use in deodorants and water treatment is healthy. Aluminium ions slow down plant growth in acidic soils. Aluminium may be a factor in Alzheimer's disease (a disease when the brain stops working and the patient is confused).[7][8] But the Alzheimer's Society says overwhelming medical and scientific opinion is that studies have not convincingly demonstrated a causal relationship between aluminium and Alzheimer's disease.[9]

Pure (white) and impure (yellow) forms of aluminium chloride
A roll of aluminium
Bauxite, aluminium ore
Aluminium cans ready for recycling at Central European Waste Management's plant in Europe

Related pages[change | change source]

References[change | change source]

  1. Meija, J.; Coplen, T. B.; Berglund, M.; Brand, W.A.; De Bièvre, P.; Gröning, M.; Holden, N.E.; Irrgeher, J. et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry 88 (3): 265-91. doi:10.1515/pac-2015-0305. https://www.degruyter.com/downloadpdf/j/pac.2016.88.issue-3/pac-2015-0305/pac-2015-0305.xml. 
  2. Dohmeier, C.; Loos, D.; Schnöckel, H. (1996). "Aluminum(I) and Gallium(I) Compounds: Syntheses, Structures, and Reactions". Angewandte Chemie International Edition 35: 129–149. doi:10.1002/anie.199601291. 
  3. D. C. Tyte (1964). "Red (B2Π–A2σ) Band System of Aluminium Monoxide". Nature 202 (4930): 383. doi:10.1038/202383a0. 
  4. Lide, D. R. (2000). "Magnetic susceptibility of the elements and inorganic compounds" (PDF). CRC Handbook of Chemistry and Physics (81st ed.). CRC Press. ISBN 0849304814.
  5. D. C. Tyte (1964). "Red (B2Π–A2σ) Band System of Aluminium Monoxide". Nature 202 (4930): 383. doi:10.1038/202383a0. 
  6. Dohmeier, C.; Loos, D.; Schnöckel, H. (1996). "Aluminum(I) and Gallium(I) Compounds: Syntheses, Structures, and Reactions". Angewandte Chemie International Edition 35: 129–149. doi:10.1002/anie.199601291. 
  7. Ferreira PC, Piai Kde A, Takayanagui AM, Segura-Muñoz SI (2008). "Aluminum as a risk factor for Alzheimer's disease". Rev Lat Am Enfermagem 16 (1): 151–7. doi:10.1590/S0104-11692008000100023. PMID 18392545. http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-11692008000100023&lng=en&nrm=iso&tlng=en. 
  8. Rondeau, V.; Jacqmin-Gadda, H.; Commenges, D.; Helmer, C.; Dartigues, J.-F. (2008). "Aluminum and Silica in Drinking Water and the Risk of Alzheimer's Disease or Cognitive Decline: Findings From 15-Year Follow-up of the PAQUID Cohort". American Journal of Epidemiology 169 (4): 489–96. doi:10.1093/aje/kwn348. PMC 2809081. PMID 19064650. 
  9. Aluminium and Alzheimer's disease, The Alzheimer's Society. Retrieved 30 January 2009.

Other websites[change | change source]