Aluminium

Aluminium (or aluminum in North American English) is a chemical element; it has symbol Al and atomic number 13. Aluminium has a density lower than that of other common metals, about one-third that of steel. It has a great affinity towards oxygen, forming a protective layer of oxide on the surface when exposed to air. Aluminium visually resembles silver, both in its color and in its great ability to reflect light. It is soft, nonmagnetic, and ductile. It has one stable isotope, ²⁷Al, which is highly abundant, making aluminium the twelfth-most common element in the universe. The radioactivity of ²⁶Al leads to it being used in radiometric dating.

Aluminium, ₁₃Al

Aluminium
Pronunciation	aluminium: /ˌæl(j)ʊˈmɪniəm/ ⓘ (AL-(y)uu-MIN-ee-əm) aluminum: /əˈluːmənəm/ ⓘ (ə-LOO-mə-nəm)
Alternative name	Aluminum (U.S., Canada)
Appearance	Silvery gray metallic
Standard atomic weight Ar°(Al)
	26.9815384±0.0000003 26.982±0.001 (abridged)
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 magnesium ← aluminium → silicon
Atomic number (Z)	13
Group	group 13 (boron group)
Period	period 3
Block	p-block
Electron configuration	[Ne] 3s2 3p1
Electrons per shell	2, 8, 3
Physical properties
Phase at STP	solid
Melting point	933.47 K ​(660.32 °C, ​1220.58 °F)
Boiling point	2743 K ​(2470 °C, ​4478 °F)
Density (at 20 °C)	2.699 g/cm3
when liquid (at m.p.)	2.375 g/cm3
Heat of fusion	10.71 kJ/mol
Heat of vaporization	284 kJ/mol
Molar heat capacity	24.20 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	common: +3 −2,? −1,? 0, +1, +2
Electronegativity	Pauling scale: 1.61
Ionization energies	1st: 577.5 kJ/mol 2nd: 1816.7 kJ/mol 3rd: 2744.8 kJ/mol (more)
Atomic radius	empirical: 143 pm
Covalent radius	121±4 pm
Van der Waals radius	184 pm
Spectral lines of aluminium
Other properties
Natural occurrence	primordial
Crystal structure	​face-centered cubic (fcc) (cF4)
Lattice constant	a = 404.93 pm (at 20 °C)
Thermal expansion	22.87×10−6/K (at 20 °C)
Thermal conductivity	237 W/(m⋅K)
Electrical resistivity	26.5 nΩ⋅m (at 20 °C)
Magnetic ordering	paramagnetic
Molar magnetic susceptibility	+16.5×10−6 cm3/mol
Young's modulus	70 GPa
Shear modulus	26 GPa
Bulk modulus	76 GPa
Speed of sound thin rod	(rolled) 5000 m/s (at r.t.)
Poisson ratio	0.35
Mohs hardness	2.75
Vickers hardness	160–350 MPa
Brinell hardness	160–550 MPa
CAS Number	7429-90-5
History
Naming	from alumine, obsolete name for alumina
Prediction	Antoine Lavoisier (1782)
Discovery	Hans Christian Ørsted (1824)
Named by	Humphry Davy (1812)
Isotopes of aluminium v e
Main isotopes Decay abun­dance half-life (t1/2) mode pro­duct 26Al trace 7.17×105 y β+84% 26Mg ε16% 26Mg γ – 27Al 100% stable
Category: Aluminium view talk edit | references

Chemically, aluminium is a post-transition metal in the boron group; as is common for the group, aluminium forms compounds primarily in the +3 oxidation state. The aluminium cation Al³⁺ is small and highly charged; as such, it has more polarizing power, and bonds formed by aluminium have a more covalent character. The strong affinity of aluminium for oxygen leads to the common occurrence of its oxides in nature. Aluminium is found on Earth primarily in rocks in the crust, where it is the third-most abundant element, after oxygen and silicon, rather than in the mantle, and virtually never as the free metal. It is obtained industrially by mining bauxite, a sedimentary rock rich in aluminium minerals.

The discovery of aluminium was announced in 1825 by Danish physicist Hans Christian Ørsted. The first industrial production of aluminium was initiated by French chemist Henri Étienne Sainte-Claire Deville in 1856. Aluminium became much more available to the public with the Hall–Héroult process developed independently by French engineer Paul Héroult and American engineer Charles Martin Hall in 1886, and the mass production of aluminium led to its extensive use in industry and everyday life. In the First and Second World Wars, aluminium was a crucial strategic resource for aviation. In 1954, aluminium became the most produced non-ferrous metal, surpassing copper. In the 21st century, most aluminium was consumed in transportation, engineering, construction, and packaging in the United States, Western Europe, and Japan.

Despite its prevalence in the environment, no living organism is known to metabolize aluminium salts, but this aluminium is well tolerated by plants and animals. Because of the abundance of these salts, the potential for a biological role for them is of interest, and studies are ongoing.