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Aluminium

Aluminium (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, a more unstable isotope, leads to it being used in radiometric dating.

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.

Isotopes
Of aluminium isotopes, only Aluminium is stable. This situation is common for elements with an odd atomic number. It is the only primordial aluminium isotope, i.e. the only one that has existed on Earth in its current form since the formation of the planet. It is therefore a mononuclidic element and its standard atomic weight is virtually the same as that of the isotope. This makes aluminium very useful in nuclear magnetic resonance (NMR), as its single stable isotope has a high NMR sensitivity. The standard atomic weight of aluminium is low in comparison with many other metals.

All other isotopes of aluminium are radioactive. The most stable of these is 26Al: while it was present along with stable 27Al in the interstellar medium from which the Solar System formed, having been produced by stellar nucleosynthesis as well, its half-life is only 717,000 years and therefore a detectable amount has not survived since the formation of the planet. However, minute traces of 26Al are produced from argon in the atmosphere by spallation caused by cosmic ray protons. The ratio of 26Al to 10Be has been used for radiodating of geological processes over 105 to 106 year time scales, in particular transport, deposition, sediment storage, burial times, and erosion. Most meteorite scientists believe that the energy released by the decay of 26Al was responsible for the melting and differentiation of some asteroids after their formation 4.55 billion years ago.

The remaining isotopes of aluminium, with mass numbers ranging from 22 to 43, all have half-lives well under an hour. Three metastable states are known, all with half-lives under a minute.

Electron shell
An aluminium atom has 13 electrons, arranged in an electron configuration of [Ne] 3s2 3p1, with three electrons beyond a stable noble gas configuration. Accordingly, the combined first three ionization energies of aluminium are far lower than the fourth ionization energy alone. Such an electron configuration is shared with the other well-characterized members of its group, boron, gallium, indium, and thallium; it is also expected for nihonium. Aluminium can surrender its three outermost electrons in many chemical reactions (see below). The electronegativity of aluminium is 1.61 (Pauling scale). A free aluminium atom has a radius of 143 pm. With the three outermost electrons removed, the radius shrinks to 39 pm for a 4-coordinated atom or 53.5 pm for a 6-coordinated atom. At standard temperature and pressure, aluminium atoms (when not affected by atoms of other elements) form a face-centered cubic crystal system bound by metallic bonding provided by atoms' outermost electrons; hence aluminium (at these conditions) is a metal. This crystal system is shared by many other metals, such as lead and copper; the size of a unit cell of aluminium is comparable to that of those other metals. The system, however, is not shared by the other members of its group: boron has ionization energies too high to allow metallization, thallium has a hexagonal close-packed structure, and gallium and indium have unusual structures that are not close-packed like those of aluminium and thallium. The few electrons that are available for metallic bonding in aluminium are a probable cause for it being soft with a low melting point and low electrical resistivity.

Bulk
Aluminium metal has an appearance ranging from silvery white to dull gray depending on its surface roughness. Aluminium mirrors are the most reflective of all metal mirrors for near ultraviolet and far infrared light. It is also one of the most reflective for light in the visible spectrum, nearly on par with silver in this respect, and the two therefore look similar. Aluminium is also good at reflecting solar radiation, although prolonged exposure to sunlight in air adds wear to the surface of the metal; this may be prevented if aluminium is anodized, which adds a protective layer of oxide on the surface.

The density of aluminium is 2.70 g/cm3, about 1/3 that of steel, much lower than other commonly encountered metals, making aluminium parts easily identifiable through their lightness. Aluminium's low density compared to most other metals arises from the fact that its nuclei are much lighter, while difference in the unit cell size does not compensate for this difference. The only lighter metals are the metals of groups 1 and 2, which apart from beryllium and magnesium are too reactive for structural use (and beryllium is very toxic). Aluminium is not as strong or stiff as steel, but the low density makes up for this in the aerospace industry and for many other applications where light weight and relatively high strength are crucial.

Pure aluminium is quite soft and lacking in strength. In most applications various aluminium alloys are used instead because of their higher strength and hardness. The yield strength of pure aluminium is 7–11 MPa, while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium is ductile, with a percent elongation of 50-70%, and malleable allowing it to be easily drawn and extruded. It is also easily machined and cast.

Aluminium is an excellent thermal and electrical conductor, having around 60% the conductivity of copper, both thermal and electrical, while having only 30% of copper's density. Aluminium is capable of superconductivity, with a superconducting critical temperature of 1.2 kelvin and a critical magnetic field of about 100 gauss (10 milliteslas). It is paramagnetic and thus essentially unaffected by static magnetic fields. The high electrical conductivity, however, means that it is strongly affected by alternating magnetic fields through the induction of eddy currents.

Chemistry
Aluminium combines characteristics of pre- and post-transition metals. Since it has few available electrons for metallic bonding, like its heavier group 13 congeners, it has the characteristic physical properties of a post-transition metal, with longer-than-expected interatomic distances. Furthermore, as Al3+ is a small and highly charged cation, it is strongly polarizing and bonding in aluminium compounds tends towards covalency; this behavior is similar to that of beryllium (Be2+), and the two display an example of a diagonal relationship.

The underlying core under aluminium's valence shell is that of the preceding noble gas, whereas those of its heavier congeners gallium, indium, thallium, and nihonium also include a filled d-subshell and in some cases a filled f-subshell. Hence, the inner electrons of aluminium shield the valence electrons almost completely, unlike those of aluminium's heavier congeners. As such, aluminium is the most electropositive metal in its group, and its hydroxide is in fact more basic than that of gallium. Aluminium also bears minor similarities to the metalloid boron in the same group: AlX3 compounds are valence isoelectronic to BX3 compounds (they have the same valence electronic structure), and both behave as Lewis acids and readily form adducts. Additionally, one of the main motifs of boron chemistry is regular icosahedral structures, and aluminium forms an important part of many icosahedral quasicrystal alloys, including the Al–Zn–Mg class.

Aluminium has a high chemical affinity to oxygen, which renders it suitable for use as a reducing agent in the thermite reaction. A fine powder of aluminium reacts explosively on contact with liquid oxygen; under normal conditions, however, aluminium forms a thin oxide layer (~5 nm at room temperature) that protects the metal from further corrosion by oxygen, water, or dilute acid, a process termed passivation. Because of its general resistance to corrosion, aluminium is one of the few metals that retains silvery reflectance in finely powdered form, making it an important component of silver-colored paints. Aluminium is not attacked by oxidizing acids because of its passivation. This allows aluminium to be used to store reagents such as nitric acid, concentrated sulfuric acid, and some organic acids.

In hot concentrated hydrochloric acid, aluminium reacts with water with evolution of hydrogen, and in aqueous sodium hydroxide or potassium hydroxide at room temperature to form aluminates—protective passivation under these conditions is negligible. Aqua regia also dissolves aluminium. Aluminium is corroded by dissolved chlorides, such as common sodium chloride, which is why household plumbing is never made from aluminium. The oxide layer on aluminium is also destroyed by contact with mercury due to amalgamation or with salts of some electropositive metals. As such, the strongest aluminium alloys are less corrosion-resistant due to galvanic reactions with alloyed copper, and aluminium's corrosion resistance is greatly reduced by aqueous salts, particularly in the presence of dissimilar metals.

Aluminium reacts with most nonmetals upon heating, forming compounds such as aluminium nitride (AlN), aluminium sulfide (Al2S3), and the aluminium halides (AlX3). It also forms a wide range of intermetallic compounds involving metals from every group on the periodic table.

Inorganic compounds
The vast majority of compounds, including all aluminium-containing minerals and all commercially significant aluminium compounds, feature aluminium in the oxidation state 3+. The coordination number of such compounds varies, but generally Al3+ is either six- or four-coordinate. Almost all compounds of aluminium(III) are colorless.

In aqueous solution, Al3+ exists as the hexaaqua cation [Al(H2O)6]3+, which has an approximate Ka of 10−5. Such solutions are acidic as this cation can act as a proton donor and progressively hydrolyze until a precipitate of aluminium hydroxide, Al(OH)3, forms. This is useful for clarification of water, as the precipitate nucleates on suspended particles in the water, hence removing them. Increasing the pH even further leads to the hydroxide dissolving again as aluminate, [Al(H2O)2(OH)4]−, is formed.

Aluminium hydroxide forms both salts and aluminates and dissolves in acid and alkali, as well as on fusion with acidic and basic oxides. This behavior of Al(OH)3 is termed amphoterism and is characteristic of weakly basic cations that form insoluble hydroxides and whose hydrated species can also donate their protons. One effect of this is that aluminium salts with weak acids are hydrolyzed in water to the aquated hydroxide and the corresponding nonmetal hydride: for example, aluminium sulfide yields hydrogen sulfide. However, some salts like aluminium carbonate exist in aqueous solution but are unstable as such; and only incomplete hydrolysis takes place for salts with strong acids, such as the halides, nitrate, and sulfate. For similar reasons, anhydrous aluminium salts cannot be made by heating their "hydrates": hydrated aluminium chloride is in fact not AlCl3·6H2O but [Al(H2O)6]Cl3, and the Al–O bonds are so strong that heating is not sufficient to break them and form Al–Cl bonds instead:

 * 2[Al(H2O)6]Cl3 $55.845$ Al2O3 + 6 HCl + 9 H2O

All four trihalides are well known. Unlike the structures of the three heavier trihalides, aluminium fluoride (AlF3) features six-coordinate aluminium, which explains its involatility and insolubility as well as high heat of formation. Each aluminium atom is surrounded by six fluorine atoms in a distorted octahedral arrangement, with each fluorine atom being shared between the corners of two octahedra. Such {AlF6} units also exist in complex fluorides such as cryolite, Na3AlF6. AlF3 melts at 1290 °C and is made by reaction of aluminium oxide with hydrogen fluoride gas at 700 °C.

With heavier halides, the coordination numbers are lower. The other trihalides are dimeric or polymeric with tetrahedral four-coordinate aluminium centers. Aluminium trichloride (AlCl3) has a layered polymeric structure below its melting point of 192.4 °C but transforms on melting to Al2Cl6 dimers. At higher temperatures those increasingly dissociate into trigonal planar AlCl3 monomers similar to the structure of BCl3. Aluminium tribromide and aluminium triiodide form Al2X6 dimers in all three phases and hence do not show such significant changes of properties upon phase change. These materials are prepared by treating aluminium with the halogen. The aluminium trihalides form many addition compounds or complexes; their Lewis acidic nature makes them useful as catalysts for the Friedel–Crafts reactions. Aluminium trichloride has major industrial uses involving this reaction, such as in the manufacture of anthraquinones and styrene; it is also often used as the precursor for many other aluminium compounds and as a reagent for converting nonmetal fluorides into the corresponding chlorides (a transhalogenation reaction).

Aluminium forms one stable oxide with the chemical formula Al2O3, commonly called alumina. It can be found in nature in the mineral corundum, α-alumina; there is also a γ-alumina phase. Its crystalline form, corundum, is very hard (Mohs hardness 9), has a high melting point of 2045 °C, has very low volatility, is chemically inert, and a good electrical insulator, it is often used in abrasives (such as toothpaste), as a refractory material, and in ceramics, as well as being the starting material for the electrolytic production of aluminium. Sapphire and ruby are impure corundum contaminated with trace amounts of other metals. The two main oxide-hydroxides, AlO(OH), are boehmite and diaspore. There are three main trihydroxides: bayerite, gibbsite, and nordstrandite, which differ in their crystalline structure (polymorphs). Many other intermediate and related structures are also known. Most are produced from ores by a variety of wet processes using acid and base. Heating the hydroxides leads to formation of corundum. These materials are of central importance to the production of aluminium and are themselves extremely useful. Some mixed oxide phases are also very useful, such as spinel (MgAl2O4), Na-β-alumina (NaAl11O17), and tricalcium aluminate (Ca3Al2O6, an important mineral phase in Portland cement).

The only stable chalcogenides under normal conditions are aluminium sulfide (Al2S3), selenide (Al2Se3), and telluride (Al2Te3). All three are prepared by direct reaction of their elements at about 1000 °C and quickly hydrolyze completely in water to yield aluminium hydroxide and the respective hydrogen chalcogenide. As aluminium is a small atom relative to these chalcogens, these have four-coordinate tetrahedral aluminium with various polymorphs having structures related to wurtzite, with two-thirds of the possible metal sites occupied either in an orderly (α) or random (β) fashion; the sulfide also has a γ form related to γ-alumina, and an unusual high-temperature hexagonal form where half the aluminium atoms have tetrahedral four-coordination and the other half have trigonal bipyramidal five-coordination.

Four pnictides – aluminium nitride (AlN), aluminium phosphide (AlP), aluminium arsenide (AlAs), and aluminium antimonide (AlSb) – are known. They are all III-V semiconductors isoelectronic to silicon and germanium, all of which but AlN have the zinc blende structure. All four can be made by high-temperature (and possibly high-pressure) direct reaction of their component elements.

Aluminium alloys well with most other metals (with the exception of most alkali metals and group 13 metals) and over 150 intermetallics with other metals are known. Preparation involves heating fixed metals together in certain proportion, followed by gradual cooling and annealing. Bonding in them is predominantly metallic and the crystal structure primarily depends on efficiency of packing.

There are few compounds with lower oxidation states. A few aluminium(I) compounds exist: AlF, AlCl, AlBr, and AlI exist in the gaseous phase when the respective trihalide is heated with aluminium, and at cryogenic temperatures. A stable derivative of aluminium monoiodide is the cyclic adduct formed with triethylamine, Al4I4(NEt3)4. Al2O and Al2S also exist but are very unstable. Very simple aluminium(II) compounds are invoked or observed in the reactions of Al metal with oxidants. For example, aluminium monoxide, AlO, has been detected in the gas phase after explosion and in stellar absorption spectra. More thoroughly investigated are compounds of the formula R4Al2 which contain an Al–Al bond and where R is a large organic ligand.

Organoaluminium compounds and related hydrides

A variety of compounds of empirical formula AlR3 and AlR1.5Cl1.5 exist. The aluminium trialkyls and triaryls are reactive, volatile, and colorless liquids or low-melting solids. They catch fire spontaneously in air and react with water, thus necessitating precautions when handling them. They often form dimers, unlike their boron analogues, but this tendency diminishes for branched-chain alkyls (e.g. Pri, Bui, Me3CCH2); for example, triisobutylaluminium exists as an equilibrium mixture of the monomer and dimer. These dimers, such as trimethylaluminium (Al2Me6), usually feature tetrahedral Al centers formed by dimerization with some alkyl group bridging between both aluminium atoms. They are hard acids and react readily with ligands, forming adducts. In industry, they are mostly used in alkene insertion reactions, as discovered by Karl Ziegler, most importantly in "growth reactions" that form long-chain unbranched primary alkenes and alcohols, and in the low-pressure polymerization of ethene and propene. There are also some heterocyclic and cluster organoaluminium compounds involving Al–N bonds.

The industrially most important aluminium hydride is lithium aluminium hydride (LiAlH4), which is used in as a reducing agent in organic chemistry. It can be produced from lithium hydride and aluminium trichloride. The simplest hydride, aluminium hydride or alane, is not as important. It is a polymer with the formula (AlH3)n, in contrast to the corresponding boron hydride that is a dimer with the formula (BH3)2.

Space
Aluminium's per-particle abundance in the Solar System is 3.15 ppm (parts per million). It is the twelfth most abundant of all elements and third most abundant among the elements that have odd atomic numbers, after hydrogen and nitrogen. The only stable isotope of aluminium, 27Al, is the eighteenth most abundant nucleus in the universe. It is created almost entirely after fusion of carbon in massive stars that will later become Type II supernovas: this fusion creates 26Mg, which upon capturing free protons and neutrons, becomes aluminium. Some smaller quantities of 27Al are created in hydrogen burning shells of evolved stars, where 26Mg can capture free protons. Essentially all aluminium now in existence is 27Al. 26Al was present in the early Solar System with abundance of 0.005% relative to 27Al but its half-life of 728,000 years is too short for any original nuclei to survive; 26Al is therefore extinct. Unlike for 27Al, hydrogen burning is the primary source of 26Al, with the nuclide emerging after a nucleus of 25Mg catches a free proton. However, the trace quantities of 26Al that do exist are the most common gamma ray emitter in the interstellar gas; if the original 26Al were still present, gamma ray maps of the Milky Way would be brighter.

Earth
Overall, the Earth is about 1.59% aluminium by mass (seventh in abundance by mass). Aluminium occurs in greater proportion in the Earth's crust than in the universe at large. This is because aluminium easily forms the oxide and becomes bound into rocks and stays in the Earth's crust, while less reactive metals sink to the core. In the Earth's crust, aluminium is the most abundant metallic element (8.23% by mass ) and the third most abundant of all elements (after oxygen and silicon). A large number of silicates in the Earth's crust contain aluminium. In contrast, the Earth's mantle is only 2.38% aluminium by mass. Aluminium also occurs in seawater at a concentration of 2 μg/kg.

Because of its strong affinity for oxygen, aluminium is almost never 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, are aluminosilicates. Aluminium also occurs in the minerals beryl, cryolite, garnet, spinel, and turquoise. Impurities in Al2O3, such as chromium and iron, yield the gemstones ruby and sapphire, respectively. Native aluminium metal is extremely rare and can only be found as a minor phase in low oxygen fugacity environments, such as the interiors of certain volcanoes. Native aluminium has been reported in cold seeps in the northeastern continental slope of the South China Sea. It is possible that these deposits resulted from bacterial reduction of tetrahydroxoaluminate Al(OH)4−.

Although aluminium is a common and widespread element, not all aluminium minerals are economically viable sources of the metal. Almost all metallic aluminium is produced from the ore bauxite (AlOx(OH)3–2x). Bauxite occurs as a weathering product of low iron and silica bedrock in tropical climatic conditions. In 2017, most bauxite was mined in Australia, China, Guinea, and India.

History

The history of aluminium has been shaped by usage of alum. The first written record of alum, made by Greek historian Herodotus, dates back to the 5th century BCE. The ancients are known to have used alum as a dyeing mordant and for city defense. After the Crusades, alum, an indispensable good in the European fabric industry, was a subject of international commerce; it was imported to Europe from the eastern Mediterranean until the mid-15th century.

The nature of alum remained unknown. Around 1530, Swiss physician Paracelsus suggested alum was a salt of an earth of alum. In 1595, German doctor and chemist Andreas Libavius experimentally confirmed this. In 1722, German chemist Friedrich Hoffmann announced his belief that the base of alum was a distinct earth. In 1754, German chemist Andreas Sigismund Marggraf synthesized alumina by boiling clay in sulfuric acid and subsequently adding potash.

Attempts to produce aluminium date back to 1760. The first successful attempt, however, was completed in 1824 by Danish physicist and chemist Hans Christian Ørsted. He reacted anhydrous aluminium chloride with potassium amalgam, yielding a lump of metal looking similar to tin. He presented his results and demonstrated a sample of the new metal in 1825. In 1827, German chemist Friedrich Wöhler repeated Ørsted's experiments but did not identify any aluminium. (The reason for this inconsistency was only discovered in 1921.) He conducted a similar experiment in the same year by mixing anhydrous aluminium chloride with potassium and produced a powder of aluminium. In 1845, he was able to produce small pieces of the metal and described some physical properties of this metal. For many years thereafter, Wöhler was credited as the discoverer of aluminium.

As Wöhler's method could not yield great quantities of aluminium, the metal remained rare; its cost exceeded that of gold. The first industrial production of aluminium was established in 1856 by French chemist Henri Etienne Sainte-Claire Deville and companions. Deville had discovered that aluminium trichloride could be reduced by sodium, which was more convenient and less expensive than potassium, which Wöhler had used. Even then, aluminium was still not of great purity and produced aluminium differed in properties by sample. Because of its electricity-conducting capacity, aluminium was used as the cap of the Washington Monument, completed in 1885. The tallest building in the world at the time, the non-corroding metal cap was intended to serve as a lightning rod peak.

The first industrial large-scale production method was independently developed in 1886 by French engineer Paul Héroult and American engineer Charles Martin Hall; it is now known as the Hall–Héroult process. The Hall–Héroult process converts alumina into metal. Austrian chemist Carl Joseph Bayer discovered a way of purifying bauxite to yield alumina, now known as the Bayer process, in 1889. Modern production of the aluminium is based on the Bayer and Hall–Héroult processes.

As large-scale production caused aluminium prices to drop, the metal became widely used in jewelry, eyeglass frames, optical instruments, tableware, and foil, and other everyday items in the 1890s and early 20th century. Aluminium's ability to form hard yet light alloys with other metals provided the metal with many uses at the time. During World War I, major governments demanded large shipments of aluminium for light strong airframes; during World War II, demand by major governments for aviation was even higher.

By the mid-20th century, aluminium had become a part of everyday life and an essential component of housewares. In 1954, production of aluminium surpassed that of copper, historically second in production only to iron, making it the most produced non-ferrous metal. During the mid-20th century, aluminium emerged as a civil engineering material, with building applications in both basic construction and interior finish work, and increasingly being used in military engineering, for both airplanes and land armor vehicle engines. Earth's first artificial satellite, launched in 1957, consisted of two separate aluminium semi-spheres joined and all subsequent space vehicles have used aluminium to some extent. The aluminium can was invented in 1956 and employed as a storage for drinks in 1958.

Throughout the 20th century, the production of aluminium rose rapidly: while the world production of aluminium in 1900 was 6,800 metric tons, the annual production first exceeded 100,000 metric tons in 1916; 1,000,000 tons in 1941; 10,000,000 tons in 1971. In the 1970s, the increased demand for aluminium made it an exchange commodity; it entered the London Metal Exchange, the oldest industrial metal exchange in the world, in 1978. The output continued to grow: the annual production of aluminium exceeded 50,000,000 metric tons in 2013.

The real price for aluminium declined from $14,000 per metric ton in 1900 to $2,340 in 1948 (in 1998 United States dollars). Extraction and processing costs were lowered over technological progress and the scale of the economies. However, the need to exploit lower-grade poorer quality deposits and the use of fast increasing input costs (above all, energy) increased the net cost of aluminium; the real price began to grow in the 1970s with the rise of energy cost. Production moved from the industrialized countries to countries where production was cheaper. Production costs in the late 20th century changed because of advances in technology, lower energy prices, exchange rates of the United States dollar, and alumina prices. The BRIC countries' combined share in primary production and primary consumption grew substantially in the first decade of the 21st century. China is accumulating an especially large share of the world's production thanks to an abundance of resources, cheap energy, and governmental stimuli; it also increased its consumption share from 2% in 1972 to 40% in 2010. In the United States, Western Europe, and Japan, most aluminium was consumed in transportation, engineering, construction, and packaging. In 2021, prices for industrial metals such as aluminium have soared to near-record levels as energy shortages in China drive up costs for electricity.

Etymology
The names aluminium and aluminum are derived from the word alumine, an obsolete term for alumina, the primary naturally occurring oxide of aluminium. Alumine was borrowed from French, which in turn derived it from alumen, the classical Latin name for alum, the mineral from which it was collected. The Latin word alumen stems from the Proto-Indo-European root *alu- meaning "bitter" or "beer".

Origins
British chemist Humphry Davy, who performed a number of experiments aimed to isolate the metal, is credited as the person who named the element. The first name proposed for the metal to be isolated from alum was alumium, which Davy suggested in an 1808 article on his electrochemical research, published in Philosophical Transactions of the Royal Society. It appeared that the name was created from the English word alum and the Latin suffix -ium; but it was customary then to give elements names originating in Latin, so this name was not adopted universally. This name was criticized by contemporary chemists from France, Germany, and Sweden, who insisted the metal should be named for the oxide, alumina, from which it would be isolated. The English name alum does not come directly from Latin, whereas alumine/alumina obviously comes from the Latin word alumen (upon declension, alumen changes to alumin-).

One example was Essai sur la Nomenclature chimique (July 1811), written in French by a Swedish chemist, Jöns Jacob Berzelius, in which the name aluminium is given to the element that would be synthesized from alum. (Another article in the same journal issue also refers to the metal whose oxide is the basis of sapphire, i.e. the same metal, as to aluminium.) A January 1811 summary of one of Davy's lectures at the Royal Society mentioned the name aluminium as a possibility. The next year, Davy published a chemistry textbook in which he used the spelling aluminum. Both spellings have coexisted since. Their usage is currently regional: aluminum dominates in the United States and Canada; aluminium is prevalent in the rest of the English-speaking world.

Spelling
In 1812, British scientist Thomas Young wrote an anonymous review of Davy's book, in which he proposed the name aluminium instead of aluminum, which he thought had a "less classical sound". This name persisted: although the -um spelling was occasionally used in Britain, the American scientific language used -ium from the start. Most scientists throughout the world used -ium in the 19th century; and it was entrenched in several other European languages, such as French, German, and Dutch. In 1828, an American lexicographer, Noah Webster, entered only the aluminum spelling in his American Dictionary of the English Language. In the 1830s, the -um spelling gained usage in the United States; by the 1860s, it had become the more common spelling there outside science. In 1892, Hall used the -um spelling in his advertising handbill for his new electrolytic method of producing the metal, despite his constant use of the -ium spelling in all the patents he filed between 1886 and 1903: it is unknown whether this spelling was introduced by mistake or intentionally; but Hall preferred aluminum since its introduction because it resembled platinum, the name of a prestigious metal. By 1890, both spellings had been common in the United States, the -ium spelling being slightly more common; by 1895, the situation had reversed; by 1900, aluminum had become twice as common as aluminium; in the next decade, the -um spelling dominated American usage. In 1925, the American Chemical Society adopted this spelling.

The International Union of Pure and Applied Chemistry (IUPAC) adopted aluminium as the standard international name for the element in 1990. In 1993, they recognized aluminum as an acceptable variant; the most recent 2005 edition of the IUPAC nomenclature of inorganic chemistry also acknowledges this spelling. IUPAC official publications use the -ium spelling as primary, and they list both where it is appropriate.

Production and refinement
The production of aluminium starts with the extraction of bauxite rock from the ground. The bauxite is processed and transformed using the Bayer process into alumina, which is then processed using the Hall–Héroult process, resulting in the final aluminium.

Aluminium production is highly energy-consuming, and so the producers tend to locate smelters in places where electric power is both plentiful and inexpensive. Production of one kilogram of aluminium requires 7 kilograms of oil energy equivalent, as compared to 1.5 kilograms for steel and 2 kilograms for plastic. As of 2019, the world's largest smelters of aluminium are located in China, India, Russia, Canada, and the United Arab Emirates, while China is by far the top producer of aluminium with a world share of fifty-five percent.

According to the International Resource Panel's Metal Stocks in Society report, the global per capita stock of aluminium in use in society (i.e. in cars, buildings, electronics, etc.) is 80 kg. Much of this is in more-developed countries (350 – per capita) rather than less-developed countries (35 kg per capita).

Bayer process
Bauxite is converted to alumina by the Bayer process. Bauxite is blended for uniform composition and then is ground. The resulting slurry is mixed with a hot solution of sodium hydroxide; the mixture is then treated in a digester vessel at a pressure well above atmospheric, dissolving the aluminium hydroxide in bauxite while converting impurities into relatively insoluble compounds:

After this reaction, the slurry is at a temperature above its atmospheric boiling point. It is cooled by removing steam as pressure is reduced. The bauxite residue is separated from the solution and discarded. The solution, free of solids, is seeded with small crystals of aluminium hydroxide; this causes decomposition of the [Al(OH)4]− ions to aluminium hydroxide. After about half of aluminium has precipitated, the mixture is sent to classifiers. Small crystals of aluminium hydroxide are collected to serve as seeding agents; coarse particles are converted to alumina by heating; the excess solution is removed by evaporation, (if needed) purified, and recycled.

Hall–Héroult process

The conversion of alumina to aluminium is achieved by the Hall–Héroult process. In this energy-intensive process, a solution of alumina in a molten (950 and 980 C) mixture of cryolite (Na3AlF6) with calcium fluoride is electrolyzed to produce metallic aluminium. The liquid aluminium sinks to the bottom of the solution and is tapped off, and usually cast into large blocks called aluminium billets for further processing.

Anodes of the electrolysis cell are made of carbon—the most resistant material against fluoride corrosion—and either bake at the process or are prebaked. The former, also called Söderberg anodes, are less power-efficient and fumes released during baking are costly to collect, which is why they are being replaced by prebaked anodes even though they save the power, energy, and labor to prebake the cathodes. Carbon for anodes should be preferably pure so that neither aluminium nor the electrolyte is contaminated with ash. Despite carbon's resistivity against corrosion, it is still consumed at a rate of 0.4–0.5 kg per each kilogram of produced aluminium. Cathodes are made of anthracite; high purity for them is not required because impurities leach only very slowly. The cathode is consumed at a rate of 0.02–0.04 kg per each kilogram of produced aluminium. A cell is usually terminated after 2–6 years following a failure of the cathode.

The Hall–Heroult process produces aluminium with a purity of above 99%. Further purification can be done by the Hoopes process. This process involves the electrolysis of molten aluminium with a sodium, barium, and aluminium fluoride electrolyte. The resulting aluminium has a purity of 99.99%.

Electric power represents about 20 to 40% of the cost of producing aluminium, depending on the location of the smelter. Aluminium production consumes roughly 5% of electricity generated in the United States. Because of this, alternatives to the Hall–Héroult process have been researched, but none has turned out to be economically feasible.

Recycling

Recovery of the metal through recycling has become an important task of the aluminium industry. Recycling was a low-profile activity until the late 1960s, when the growing use of aluminium beverage cans brought it to public awareness. Recycling involves melting the scrap, a process that requires only 5% of the energy used to produce aluminium from ore, though a significant part (up to 15% of the input material) is lost as dross (ash-like oxide). An aluminium stack melter produces significantly less dross, with values reported below 1%.

White dross from primary aluminium production and from secondary recycling operations still contains useful quantities of aluminium that can be extracted industrially. The process produces aluminium billets, together with a highly complex waste material. This waste is difficult to manage. It reacts with water, releasing a mixture of gases (including, among others, hydrogen, acetylene, and ammonia), which spontaneously ignites on contact with air; contact with damp air results in the release of copious quantities of ammonia gas. Despite these difficulties, the waste is used as a filler in asphalt and concrete.

Metal
The global production of aluminium in 2016 was 58.8 million metric tons. It exceeded that of any other metal except iron (1,231 million metric tons).

Aluminium is almost always alloyed, which markedly improves its mechanical properties, especially when tempered. For example, the common aluminium foils and beverage cans are alloys of 92% to 99% aluminium. The main alloying agents are copper, zinc, magnesium, manganese, and silicon (e.g., duralumin) with the levels of other metals in a few percent by weight. Aluminium, both wrought and cast, has been alloyed with: manganese, silicon, magnesium, copper and zinc among others.

The major uses for aluminium are in:
 * Transportation (automobiles, aircraft, trucks, railway cars, marine vessels, bicycles, spacecraft, etc.). Aluminium is used because of its low density;
 * Packaging (cans, foil, frame, etc.). Aluminium is used because it is non-toxic (see below), non-adsorptive, and splinter-proof;
 * Building and construction (windows, doors, siding, building wire, sheathing, roofing, etc.). Since steel is cheaper, aluminium is used when lightness, corrosion resistance, or engineering features are important;
 * Electricity-related uses (conductor alloys, motors, and generators, transformers, capacitors, etc.). Aluminium is used because it is relatively cheap, highly conductive, has adequate mechanical strength and low density, and resists corrosion;
 * A wide range of household items, from cooking utensils to furniture. Low density, good appearance, ease of fabrication, and durability are the key factors of aluminium usage;
 * Machinery and equipment (processing equipment, pipes, tools). Aluminium is used because of its corrosion resistance, non-pyrophoricity, and mechanical strength.

Compounds
The great majority (about 90%) of aluminium oxide is converted to metallic aluminium. Being a very hard material (Mohs hardness 9), alumina is widely used as an abrasive; being extraordinarily chemically inert, it is useful in highly reactive environments such as high pressure sodium lamps. Aluminium oxide is commonly used as a catalyst for industrial processes; e.g. the Claus process to convert hydrogen sulfide to sulfur in refineries and to alkylate amines. Many industrial catalysts are supported by alumina, meaning that the expensive catalyst material is dispersed over a surface of the inert alumina. Another principal use is as a drying agent or absorbent.

Several sulfates of aluminium have industrial and commercial application. Aluminium sulfate (in its hydrate form) is produced on the annual scale of several millions of metric tons. About two-thirds is consumed in water treatment. The next major application is in the manufacture of paper. It is also used as a mordant in dyeing, in pickling seeds, deodorizing of mineral oils, in leather tanning, and in production of other aluminium compounds. Two kinds of alum, ammonium alum and potassium alum, were formerly used as mordants and in leather tanning, but their use has significantly declined following availability of high-purity aluminium sulfate. Anhydrous aluminium chloride is used as a catalyst in chemical and petrochemical industries, the dyeing industry, and in synthesis of various inorganic and organic compounds. Aluminium hydroxychlorides are used in purifying water, in the paper industry, and as antiperspirants. Sodium aluminate is used in treating water and as an accelerator of solidification of cement.

Many aluminium compounds have niche applications, for example:
 * Aluminium acetate in solution is used as an astringent.
 * Aluminium phosphate is used in the manufacture of glass, ceramic, pulp and paper products, cosmetics, paints, varnishes, and in dental cement.
 * Aluminium hydroxide is used as an antacid, and mordant; it is used also in water purification, the manufacture of glass and ceramics, and in the waterproofing of fabrics.
 * Lithium aluminium hydride is a powerful reducing agent used in organic chemistry.
 * Organoaluminiums are used as Lewis acids and co-catalysts.
 * Methylaluminoxane is a co-catalyst for Ziegler–Natta olefin polymerization to produce vinyl polymers such as polyethene.
 * Aqueous aluminium ions (such as aqueous aluminium sulfate) are used to treat against fish parasites such as Gyrodactylus salaris.
 * In many vaccines, certain aluminium salts serve as an immune adjuvant (immune response booster) to allow the protein in the vaccine to achieve sufficient potency as an immune stimulant. Until 2004, most of the adjuvants used in vaccines were aluminium-adjuvanted.

Biology

Despite its widespread occurrence in the Earth's crust, aluminium has no known function in biology. At pH 6–9 (relevant for most natural waters), aluminium precipitates out of water as the hydroxide and is hence not available; most elements behaving this way have no biological role or are toxic. Aluminium sulfate has an LD50 of 6207 mg/kg (oral, mouse), which corresponds to 435 grams (about one pound) for a 70 kg person.

Toxicity
Aluminium is classified as a non-carcinogen by the United States Department of Health and Human Services. A review published in 1988 said that there was little evidence that normal exposure to aluminium presents a risk to healthy adult, and a 2014 multi-element toxicology review was unable to find deleterious effects of aluminium consumed in amounts not greater than 40 mg/day per kg of body mass. Most aluminium consumed will leave the body in feces; most of the small part of it that enters the bloodstream, will be excreted via urine; nevertheless some aluminium does pass the blood-brain barrier and is lodged preferentially in the brains of Alzheimer's patients. Evidence published in 1989 indicates that, for Alzheimer's patients, aluminium may act by electrostatically crosslinking proteins, thus down-regulating genes in the superior temporal gyrus.

Effects
Aluminium, although rarely, can cause vitamin D-resistant osteomalacia, erythropoietin-resistant microcytic anemia, and central nervous system alterations. People with kidney insufficiency are especially at a risk. Chronic ingestion of hydrated aluminium silicates (for excess gastric acidity control) may result in aluminium binding to intestinal contents and increased elimination of other metals, such as iron or zinc; sufficiently high doses (>50 g/day) can cause anemia.

During the 1988 Camelford water pollution incident people in Camelford had their drinking water contaminated with aluminium sulfate for several weeks. A final report into the incident in 2013 concluded it was unlikely that this had caused long-term health problems.

Aluminium has been suspected of being a possible cause of Alzheimer's disease, but research into this for over 40 years has found,, no good evidence of causal effect.

Aluminium increases estrogen-related gene expression in human breast cancer cells cultured in the laboratory. In very high doses, aluminium is associated with altered function of the blood–brain barrier. A small percentage of people have contact allergies to aluminium and experience itchy red rashes, headache, muscle pain, joint pain, poor memory, insomnia, depression, asthma, irritable bowel syndrome, or other symptoms upon contact with products containing aluminium.

Exposure to powdered aluminium or aluminium welding fumes can cause pulmonary fibrosis. Fine aluminium powder can ignite or explode, posing another workplace hazard.

Exposure routes
Food is the main source of aluminium. Drinking water contains more aluminium than solid food; however, aluminium in food may be absorbed more than aluminium from water. Major sources of human oral exposure to aluminium include food (due to its use in food additives, food and beverage packaging, and cooking utensils), drinking water (due to its use in municipal water treatment), and aluminium-containing medications (particularly antacid/antiulcer and buffered aspirin formulations). Dietary exposure in Europeans averages to 0.2–1.5 mg/kg/week but can be as high as 2.3 mg/kg/week. Higher exposure levels of aluminium are mostly limited to miners, aluminium production workers, and dialysis patients.

Consumption of antacids, antiperspirants, vaccines, and cosmetics provide possible routes of exposure. Consumption of acidic foods or liquids with aluminium enhances aluminium absorption, and maltol has been shown to increase the accumulation of aluminium in nerve and bone tissues.

Treatment
In case of suspected sudden intake of a large amount of aluminium, the only treatment is deferoxamine mesylate which may be given to help eliminate aluminium from the body by chelation. However, this should be applied with caution as this reduces not only aluminium body levels, but also those of other metals such as copper or iron.

Environmental effects
High levels of aluminium occur near mining sites; small amounts of aluminium are released to the environment at the coal-fired power plants or incinerators. Aluminium in the air is washed out by the rain or normally settles down but small particles of aluminium remain in the air for a long time.

Acidic precipitation is the main natural factor to mobilize aluminium from natural sources and the main reason for the environmental effects of aluminium; however, the main factor of presence of aluminium in salt and freshwater are the industrial processes that also release aluminium into air.

In water, aluminium acts as a toxiс agent on gill-breathing animals such as fish when the water is acidic, in which aluminium may precipitate on gills, which causes loss of plasma- and hemolymph ions leading to osmoregulatory failure. Organic complexes of aluminium may be easily absorbed and interfere with metabolism in mammals and birds, even though this rarely happens in practice.

Aluminium is primary among the factors that reduce plant growth on acidic soils. Although it is generally harmless to plant growth in pH-neutral soils, in acid soils the concentration of toxic Al3+ cations increases and disturbs root growth and function. Wheat has developed a tolerance to aluminium, releasing organic compounds that bind to harmful aluminium cations. Sorghum is believed to have the same tolerance mechanism.

Aluminium production possesses its own challenges to the environment on each step of the production process. The major challenge is the greenhouse gas emissions. These gases result from electrical consumption of the smelters and the byproducts of processing. The most potent of these gases are perfluorocarbons from the smelting process. Released sulfur dioxide is one of the primary precursors of acid rain.

Biodegradation of metallic aluminium is extremely rare; most aluminium-corroding organisms do not directly attack or consume the aluminium, but instead produce corrosive wastes. The fungus Geotrichum candidum can consume the aluminium in compact discs. The bacterium Pseudomonas aeruginosa and the fungus Cladosporium resinae are commonly detected in aircraft fuel tanks that use kerosene-based fuels (not avgas), and laboratory cultures can degrade aluminium.

title: Aluminium


text:
Advanced Chemistry

Advanced Chemistry is a German hip hop group from Heidelberg, a scenic city in Baden-Württemberg, South Germany. Advanced Chemistry was founded in 1987 by Toni L, Linguist, Gee-One, DJ Mike MD (Mike Dippon) and MC Torch. Each member of the group holds German citizenship, and Toni L, Linguist, and Torch are of Italian, Ghanaian, and Haitian backgrounds, respectively.

Influenced by North American socially conscious rap and the Native tongues movement, Advanced Chemistry is regarded as one of the main pioneers in German hip hop. They were one of the first groups to rap in German (although their name is in English). Furthermore, their songs tackled controversial social and political issues, distinguishing them from early German hip hop group "Die Fantastischen Vier" (The Fantastic Four), which had a more light-hearted, playful, party image.

Career
Advanced Chemistry frequently rapped about their lives and experiences as children of immigrants, exposing the marginalization experienced by most ethnic minorities in Germany, and the feelings of frustration and resentment that being denied a German identity can cause. The song "Fremd im eigenen Land" (Foreign in your own nation) was released by Advanced Chemistry in November 1992. The single became a staple in the German hip hop scene. It made a strong statement about the status of immigrants throughout Germany, as the group was composed of multi-national and multi-racial members. The video shows several members brandishing their German passports as a demonstration of their German citizenship to skeptical and unaccepting 'ethnic' Germans.

This idea of national identity is important, as many rap artists in Germany have been of foreign origin. These so-called Gastarbeiter (guest workers) children saw breakdance, graffiti, rap music, and hip hop culture as a means of expressing themselves. Since the release of "Fremd im eigenen Land", many other German-language rappers have also tried to confront anti-immigrant ideas and develop themes of citizenship. However, though many ethnic minority youth in Germany find these German identity themes appealing, others view the desire of immigrants to be seen as German negatively, and they have actively sought to revive and recreate concepts of identity in connection to traditional ethnic origins.

Advanced Chemistry helped to found the German chapter of the Zulu nation.

The rivalry between Advanced Chemistry and Die Fantastischen Vier has served to highlight a dichotomy in the routes that hip hop has taken in becoming a part of the German soundscape. While Die Fantastischen Vier may be said to view hip hop primarily as an aesthetic art form, Advanced Chemistry understand hip hop as being inextricably linked to the social and political circumstances under which it is created. For Advanced Chemistry, hip hop is a “vehicle of general human emancipation,”. In their undertaking of social and political issues, the band introduced the term "Afro-German" into the context of German hip hop, and the theme of race is highlighted in much of their music.

With the release of the single “Fremd im eigenen Land”, Advanced Chemistry separated itself from the rest of the rap being produced in Germany. This single was the first of its kind to go beyond simply imitating US rap and addressed the current issues of the time. Fremd im eigenen Land which translates to “foreign in my own country” dealt with the widespread racism that non-white German citizens faced. This change from simple imitation to political commentary was the start of German identification with rap. The sound of “Fremd im eigenen Land” was influenced by the 'wall of noise' created by Public Enemy's producers, The Bomb Squad.

After the reunification of Germany, an abundance of anti-immigrant sentiment emerged, as well as attacks on the homes of refugees in the early 1990s. Advanced Chemistry came to prominence in the wake of these actions because of their pro-multicultural society stance in their music. Advanced Chemistry's attitudes revolve around their attempts to create a distinct "Germanness" in hip hop, as opposed to imitating American hip hop as other groups had done. Torch has said, "What the Americans do is exotic for us because we don't live like they do. What they do seems to be more interesting and newer. But not for me.  For me it's more exciting to experience my fellow Germans in new contexts...For me, it's interesting to see what the kids try to do that's different from what I know." Advanced Chemistry were the first to use the term "Afro-German" in a hip hop context. This was part of the pro-immigrant political message they sent via their music.

While Advanced Chemistry's use of the German language in their rap allows them to make claims to authenticity and true German heritage, bolstering pro-immigration sentiment, their style can also be problematic for immigrant notions of any real ethnic roots. Indeed, part of the Turkish ethnic minority of Frankfurt views Advanced Chemistry's appeal to the German image as a "symbolic betrayal of the right of ethnic minorities to 'roots' or to any expression of cultural heritage." In this sense, their rap represents a complex social discourse internal to the German soundscape in which they attempt to negotiate immigrant assimilation into a xenophobic German culture with the maintenance of their own separate cultural traditions. It is quite possibly the feelings of alienation from the pure-blooded German demographic that drive Advanced Chemistry to attack nationalistic ideologies by asserting their "Germanness" as a group composed primarily of ethnic others. The response to this pseudo-German authenticity can be seen in what Andy Bennett refers to as "alternative forms of local hip hop culture which actively seek to rediscover and, in many cases, reconstruct notions of identity tied to cultural roots." These alternative local hip hop cultures include oriental hip hop, the members of which cling to their Turkish heritage and are confused by Advanced Chemistry's elicitation of a German identity politics to which they technically do not belong. This cultural binary illustrates that rap has taken different routes in Germany and that, even among an already isolated immigrant population, there is still disunity and, especially, disagreement on the relative importance of assimilation versus cultural defiance. According to German hip hop enthusiast 9@home, Advanced Chemistry is part of a "hip-hop movement [which] took a clear stance for the minorities and against the [marginalization] of immigrants who...might be German on paper, but not in real life," which speaks to the group's hope of actually being recognized as German citizens and not foreigners, despite their various other ethnic and cultural ties.

Influences
Advanced Chemistry's work was rooted in German history and the country's specific political realities. However, they also drew inspiration from African-American hip-hop acts like A Tribe Called Quest and Public Enemy, who had helped bring a soulful sound and political consciousness to American hip-hop. One member, Torch, later explicitly listed his references on his solo song "Als (When I Was in School):" "My favorite subject, which was quickly discovered poetry in load Poets, awakens the intellect or policy at Chuck D I'll never forget the lyrics by Public Enemy." Torch goes on to list other American rappers like Biz Markie, Big Daddy Kane and Dr. Dre as influences.

Discography

 * 1992 - "Fremd im eigenen Land" (12"/MCD, MZEE)
 * 1993 - "Welcher Pfad führt zur Geschichte" (12"/MCD, MZEE)
 * 1994 - "Operation § 3" (12"/MCD)
 * 1994 - "Dir fehlt der Funk!" (12"/MCD)
 * 1995 - Advanced Chemistry (2xLP/CD)

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Advanced Chemistry


text:
Anglican Communion

The Anglican Communion is the third largest Christian communion after the Roman Catholic and Eastern Orthodox churches. Formally founded in 1867 in London, the communion has more than 85 million members  within the Church of England and other autocephalous national and regional churches in full communion. The traditional origins of Anglican doctrine are summarised in the Thirty-nine Articles (1571). The archbishop of Canterbury (, Justin Welby) in England acts as a focus of unity, recognised as primus inter pares ("first among equals"), but does not exercise authority in Anglican provinces outside of the Church of England. Most, but not all, member churches of the communion are the historic national or regional Anglican churches.

The Anglican Communion was officially and formally organised and recognised as such at the Lambeth Conference in 1867 in London under the leadership of Charles Longley, Archbishop of Canterbury. The churches of the Anglican Communion consider themselves to be part of the one, holy, catholic and apostolic church, and to be both Catholic and Reformed. As in the Church of England itself, the Anglican Communion includes the broad spectrum of beliefs and liturgical practises found in the Evangelical, Central and Anglo-Catholic traditions of Anglicanism. Each national or regional church is fully independent, retaining its own legislative process and episcopal polity under the leadership of local primates. For some adherents, Anglicanism represents a non-papal Catholicism, for others a form of Protestantism though without a guiding figure such as Martin Luther, John Knox, John Calvin, Huldrych Zwingli, John Wesley or Jan Hus, or, for yet others, a combination of the two.

Most of its members live in the Anglosphere of former British territories. Full participation in the sacramental life of each church is available to all communicant members. Because of their historical link to England (ecclesia anglicana means "English church"), some of the member churches are known as "Anglican", such as the Anglican Church of Canada. Others, for example the Church of Ireland and the Scottish and American Episcopal churches, have official names that do not include "Anglican". Conversely, some churches that do use the name "Anglican" are not part of the communion. These have generally disaffiliated over disagreement with the direction of the communion.

On 20 February 2023, ten communion provinces and Anglican realignment churches within the Global South Fellowship of Anglican Churches released a statement stating that they had declared "impaired communion" with the Church of England and no longer recognised Justin Welby as "first among equals" among the bishops of the communion, de facto marking a schism within the Anglican Communion.

History
The Anglican Communion traces much of its growth to the older mission organisations of the Church of England such as the Society for Promoting Christian Knowledge (founded 1698), the Society for the Propagation of the Gospel in Foreign Parts (founded 1701) and the Church Missionary Society (founded 1799). The Church of England (which until the 20th century included the Church in Wales) initially separated from the Roman Catholic Church in 1534 in the reign of Henry VIII, reunited briefly in 1555 under Mary I and then separated again in 1570 under Elizabeth I (the Roman Catholic Church excommunicated Elizabeth I in 1570 in response to the Act of Supremacy 1559).

The Church of England has always thought of itself not as a new foundation but rather as a reformed continuation of the ancient "English Church" (Ecclesia Anglicana) and a reassertion of that church's rights. As such it was a distinctly national phenomenon. The Church of Scotland was formed as a separate church from the Roman Catholic Church as a result of the Scottish Reformation in 1560 and the later formation of the Scottish Episcopal Church began in 1582 in the reign of James VI over disagreements about the role of bishops.

The oldest-surviving Anglican church building outside the British Isles (Britain and Ireland) is St Peter's Church in St George's, Bermuda, established in 1612 (though the actual building had to be rebuilt several times over the following century). This is also the oldest surviving non-Roman Catholic church in the New World. It remained part of the Church of England until 1978 when the Anglican Church of Bermuda was formed. The Church of England was the established church not only in England, but in its trans-Oceanic colonies. Thus the only member churches of the present Anglican Communion existing by the mid-18th century were the Church of England, its closely linked sister church the Church of Ireland (which also separated from Roman Catholicism under Henry VIII) and the Scottish Episcopal Church which for parts of the 17th and 18th centuries was partially underground (it was suspected of Jacobite sympathies).

Global spread of Anglicanism
The enormous expansion in the 18th and 19th centuries of the British Empire brought Anglicanism along with it. At first all these colonial churches were under the jurisdiction of the bishop of London. After the American Revolution, the parishes in the newly independent country found it necessary to break formally from a church whose supreme governor was (and remains) the British monarch. Thus they formed their own dioceses and national church, the Episcopal Church in the United States of America, in a mostly amicable separation.

At about the same time, in the colonies which remained linked to the crown, the Church of England began to appoint colonial bishops. In 1787, Charles Inglis (Bishop of Nova Scotia) was appointed with a jurisdiction over all of British North America; in time several more colleagues were appointed to other cities in present-day Canada. In 1814, a bishop of Calcutta was made; in 1824 the first bishop was sent to the West Indies and in 1836 to Australia. By 1840 there were still only ten colonial bishops for the Church of England; but even this small beginning greatly facilitated the growth of Anglicanism around the world. In 1841, a "Colonial Bishoprics Council" was set up and soon many more dioceses were created.

In time, it became natural to group these into provinces and a metropolitan bishop was appointed for each province. Although it had at first been somewhat established in many colonies, in 1861 it was ruled that, except where specifically established, the Church of England had just the same legal position as any other church. Thus a colonial bishop and colonial diocese was by nature quite a different thing from their counterparts back home. In time bishops came to be appointed locally rather than from England and eventually national synods began to pass ecclesiastical legislation independent of England.

A crucial step in the development of the modern communion was the idea of the Lambeth Conferences (discussed above). These conferences demonstrated that the bishops of disparate churches could manifest the unity of the church in their episcopal collegiality despite the absence of universal legal ties. Some bishops were initially reluctant to attend, fearing that the meeting would declare itself a council with power to legislate for the church; but it agreed to pass only advisory resolutions. These Lambeth Conferences have been held roughly every ten years since 1878 (the second such conference) and remain the most visible coming-together of the whole communion.

The Lambeth Conference of 1998 included what has been seen by Philip Jenkins and others as a "watershed in global Christianity". The 1998 Lambeth Conference considered the issue of the theology of same-sex attraction in relation to human sexuality. At this 1998 conference for the first time in centuries the Christians of developing regions, especially, Africa, Asia and Latin America, prevailed over the bishops of more prosperous countries (many from the US, Canada and the UK) who supported a redefinition of Anglican doctrine. Seen in this light, 1998 is a date that marked the shift from a West-dominated Christianity to one wherein the growing churches of the two-thirds world are predominant.

Differences and controversies
Some effects of the Anglican Communion's dispersed authority have been differences of opinion (and conflicts) arising over divergent practices and doctrines in parts of the communion. Disputes that had been confined to the Church of England could be dealt with legislatively in that realm, but as the communion spread out into new countries and territories, and disparate cultures, controversies often multiplied and intensified. These controversies have generally been of two types: liturgical and social.

Rapid social change and the dissipation of British cultural hegemony over its former colonies contributed to disputes over the role of women, and the parameters of marriage and divorce. In the late 1970s, the Continuing Anglican movement produced a number of new church bodies in opposition to women's ordination, prayer book changes, and the new understandings concerning marriage.

Anglo-Catholicism
The first such controversy of note concerned that of the growing influence of the Catholic Revival manifested in the Tractarian and so-called Ritualist controversies of the late 19th and early 20th centuries. This controversy produced the Free Church of England and, in the United States and Canada, the Reformed Episcopal Church.

Abortion and euthanasia
While individual Anglicans and member churches within the communion differ in good faith over the circumstances in which abortion should or should not be permitted, Lambeth Conference resolutions have consistently held to a conservative view on the issue. The 1930 conference, the first to be held since the initial legalisation of abortion in Europe (in Russia in 1920), stated:

"The Conference further records its abhorrence of the sinful practice of abortion."

The 1958 conference's Family in Contemporary Society report affirmed the following position on abortion and was commended by the 1968 ccnference:

"In the strongest terms Christians reject the practice of induced abortion or infanticide, which involves the killing of a life already conceived (as well as a violation of the personality of the mother), save at the dictate of strict and undeniable medical necessity ... the sacredness of life is, in Christian eyes, an absolute which should not be violated."

The subsequent Lambeth Conference, in 1978, made no change to this position and commended the need for "programmes at diocesan level, involving both men and women ... to emphasise the sacredness of all human life, the moral issues inherent in clinical abortion, and the possible implications of genetic engineering."

In the context of debates around and proposals for the legalisation of euthanasia and assisted suicide, the 1998 conference affirmed that "life is God-given and has intrinsic sanctity, significance and worth".

Same-sex unions and LGBT clergy
More recently, disagreements over homosexuality have strained the unity of the communion as well as its relationships with other Christian denominations, leading to another round of withdrawals from the Anglican Communion. Some churches were founded outside the Anglican Communion in the late 20th and early 21st centuries, largely in opposition to the ordination of openly homosexual bishops and other clergy and are usually referred to as belonging to the Anglican realignment movement, or else as "orthodox" Anglicans. These disagreements were especially noted when the Episcopal Church (US) consecrated an openly gay bishop in a same-sex relationship, Gene Robinson, in 2003, which led some Episcopalians to defect and found the Anglican Church in North America (ACNA); then, the debate reignited when the Church of England agreed to allow clergy to enter into same-sex civil partnerships, as long as they remained celibate, in 2005. The Church of Nigeria opposed the Episcopal Church's decision as well as the Church of England's approval for celibate civil partnerships.

"The more liberal provinces that are open to changing Church doctrine on marriage in order to allow for same-sex unions include Brazil, Canada, New Zealand, Scotland, South India, South Africa, the US and Wales". In 2023, the Church of England announced that it will authorise "prayers of thanksgiving, dedication and for God's blessing for same-sex couples". The Church of England also permits clergy to enter into same-sex civil partnerships. In 2024, the Church of England's General Synod voted to support allowing clergy to enter in civil same-sex marriages. In 2023, the Anglican Church of Southern Africa's bishops approved the drafting of prayers that could be said with same-sex couples and the draft prayers were published for consideration in 2024. The Church of Ireland has no official position on civil unions, and one senior cleric has entered into a same-sex civil partnership. The Church of Ireland recognised that it will "treat civil partners the same as spouses". The Anglican Church of Australia does not have an official position on homosexuality.

The conservative Anglican churches encouraging the realignment movement are more concentrated in the Global South. For example, the Anglican Church of Kenya, the Church of Nigeria and the Church of Uganda have opposed homosexuality. GAFCON, a fellowship of conservative Anglican churches, has appointed "missionary bishops" in response to the disagreements with the perceived liberalisation in the Anglican churches in North America and Europe. In 2023, ten archbishops within the Anglican Communion and two breakaway churches in North America and Brazil from the Global South Fellowship of Anglican Churches (GSFA) declared a state of impaired communion with the Church of England and announced that they would no longer recognise the archbishop of Canterbury as the "first among equals" among the bishops in the Anglican Communion. However, in the same statement, the ten archbishops said that they would not leave the Anglican Communion. In 2024, the GSFA met again establishing "a new structure," no longer recognising the Archbishop of Canterbury "as the de facto leader" of the Anglican Communion, but the GSFA reiterated that they intend to remain in the Anglican Communion.

Debates about social theology and ethics have occurred at the same time as debates on prayer book revision and the acceptable grounds for achieving full communion with non-Anglican churches.

Ecclesiology, polity and ethos
The Anglican Communion has no official legal existence nor any governing structure that might exercise authority over the member churches. There is an Anglican Communion Office in London, under the aegis of the archbishop of Canterbury, but it serves only in a supporting and organisational role. The communion is held together by a shared history, expressed in its ecclesiology, polity and ethos, and also by participation in international consultative bodies.

Three elements have been important in holding the communion together: first, the shared ecclesial structure of the component churches, manifested in an episcopal polity maintained through the apostolic succession of bishops and synodical government; second, the principle of belief expressed in worship, investing importance in approved prayer books and their rubrics; and third, the historical documents and the writings of early Anglican divines that have influenced the ethos of the communion.

Originally, the Church of England was self-contained and relied for its unity and identity on its own history, its traditional legal and episcopal structure, and its status as an established church of the state. As such, Anglicanism was from the outset a movement with an explicitly episcopal polity, a characteristic that has been vital in maintaining the unity of the communion by conveying the episcopate's role in manifesting visible catholicity and ecumenism.

Early in its development following the English Reformation, Anglicanism developed a vernacular prayer book, called the Book of Common Prayer. Unlike other traditions, Anglicanism has never been governed by a magisterium nor by appeal to one founding theologian, nor by an extra-credal summary of doctrine (such as the Westminster Confession of the Presbyterian churches). Instead, Anglicans have typically appealed to the Book of Common Prayer (1662) and its offshoots as a guide to Anglican theology and practise. This has had the effect of inculcating in Anglican identity and confession the principle of lex orandi, lex credendi ("the law of praying [is] the law of believing").

Protracted conflict through the 17th century, with radical Protestants on the one hand and Roman Catholics who recognised the primacy of the Pope on the other, resulted in an association of churches that was both deliberately vague about doctrinal principles, yet bold in developing parameters of acceptable deviation. These parameters were most clearly articulated in the various rubrics of the successive prayer books, as well as the Thirty-nine Articles of Religion (1563). These articles have historically shaped and continue to direct the ethos of the communion, an ethos reinforced by its interpretation and expansion by such influential early theologians such as Richard Hooker, Lancelot Andrewes and John Cosin.

With the expansion of the British Empire and the growth of Anglicanism outside Great Britain and Ireland, the communion sought to establish new vehicles of unity. The first major expressions of this were the Lambeth Conferences of the communion's bishops, first convened in 1867 by Charles Longley, the archbishop of Canterbury. From the beginning, these were not intended to displace the autonomy of the emerging provinces of the communion, but to "discuss matters of practical interest, and pronounce what we deem expedient in resolutions which may serve as safe guides to future action".

Chicago Lambeth Quadrilateral
One of the enduringly influential early resolutions of the conference was the so-called Chicago-Lambeth Quadrilateral of 1888. Its intent was to provide the basis for discussions of reunion with the Roman Catholic and Orthodox churches, but it had the ancillary effect of establishing parameters of Anglican identity. It establishes four principles with these words: "That, in the opinion of this Conference, the following Articles supply a basis on which approach may be by God's blessing made towards Home Reunion:

(a) The Holy Scriptures of the Old and New Testaments, as 'containing all things necessary to salvation,' and as being the rule and ultimate standard of faith.

(b) The Apostles' Creed, as the Baptismal Symbol; and the Nicene Creed, as the sufficient statement of the Christian faith.

(c) The two Sacraments ordained by Christ Himself – Baptism and the Supper of the Lord – ministered with unfailing use of Christ's Words of Institution, and of the elements ordained by Him.

(d) The Historic Episcopate, locally adapted in the methods of its administration to the varying needs of the nations and peoples called of God into the Unity of His Church."

Instruments of communion
As mentioned above, the Anglican Communion has no international juridical organisation. The archbishop of Canterbury's role is strictly symbolic and unifying and the communion's three international bodies are consultative and collaborative, their resolutions having no legal effect on the autonomous provinces of the communion. Taken together, however, the four do function as "instruments of communion", since all churches of the communion participate in them. In order of antiquity, they are:

 * 1) The archbishop of Canterbury functions as the spiritual head of the communion. The archbishop is the focus of unity, since no church claims membership in the communion without being in communion with him. The present archbishop is Justin Welby.
 * 2) The Lambeth Conference (first held in 1867) is the oldest international consultation. It is a forum for bishops of the communion to reinforce unity and collegiality through manifesting the episcopate, to discuss matters of mutual concern, and to pass resolutions intended to act as guideposts. It is held roughly every ten years and invitation is by the archbishop of Canterbury.
 * 3) The Anglican Consultative Council (first met in 1971) was created by a 1968 Lambeth Conference resolution, and meets usually at three-yearly intervals. The council consists of representative bishops, other clergy and laity chosen by the 38 provinces. The body has a permanent secretariat, the Anglican Communion Office, of which the archbishop of Canterbury is president.
 * 4) The Primates' Meeting (first met in 1979) is the most recent manifestation of international consultation and deliberation, having been first convened by Archbishop Donald Coggan as a forum for "leisurely thought, prayer and deep consultation".

Since there is no binding authority in the Anglican Communion, these international bodies are a vehicle for consultation and persuasion. In recent times, persuasion has tipped over into debates over conformity in certain areas of doctrine, discipline, worship and ethics. The most notable example has been the objection of many provinces of the communion (particularly in Africa and Asia) to the changing acceptance of LGBTQ+ individuals in the North American churches (e.g., by blessing same-sex unions and ordaining and consecrating same-sex relationships) and to the process by which changes were undertaken. (See Anglican realignment)

Those who objected condemned these actions as unscriptural, unilateral, and without the agreement of the communion prior to these steps being taken. In response, the American Episcopal Church and the Anglican Church of Canada answered that the actions had been undertaken after lengthy scriptural and theological reflection, legally in accordance with their own canons and constitutions and after extensive consultation with the provinces of the communion.

The Primates' Meeting voted to request the two churches to withdraw their delegates from the 2005 meeting of the Anglican Consultative Council. Canada and the United States decided to attend the meeting but without exercising their right to vote. They have not been expelled or suspended, since there is no mechanism in this voluntary association to suspend or expel an independent province of the communion. Since membership is based on a province's communion with Canterbury, expulsion would require the archbishop of Canterbury's refusal to be in communion with the affected jurisdictions. In line with the suggestion of the Windsor Report, Rowan Williams (the then archbishop of Canterbury) established a working group to examine the feasibility of an Anglican covenant which would articulate the conditions for communion in some fashion.

Provinces
[[File:AnglicanCommunionProvinces.png|thumb|upright=3.65| A world map showing the provinces of the Anglican Communion:

The Church of Ireland serves both Northern Ireland and the Republic of Ireland and the Anglican Church of Korea serves South Korea and, theoretically, North Korea. Indian Anglicanism is divided into the Church of North India, the Church of South India and the Mar Thoma Church. The Diocese in Europe (formally the Diocese of Gibraltar in Europe), in the Province of Canterbury, is also present in Portugal and Spain. The Episcopal Church, USA-affiliated Convocation of Episcopal Churches in Europe has affiliates in Austria, Belgium, France, Georgia, Germany and Italy. |center]]

The Anglican Communion consists of forty-two autonomous provinces each with its own primate and governing structure. These provinces may take the form of national churches (such as in Canada, Uganda, or Japan) or a collection of nations (such as the West Indies, Central Africa, or Southeast Asia).

Extraprovincial churches
In addition to the forty-two provinces, there are five extraprovincial churches under the metropolitical authority of the archbishop of Canterbury.

New provinces in formation
In September 2020, the Archbishop of Canterbury announced that he had asked the bishops of the Church of Ceylon to begin planning for the formation of an autonomous province of Ceylon, so as to end his current position as metropolitan of the two dioceses in that country.

Churches in full communion
In addition to other member churches, the churches of the Anglican Communion are in full communion with the Old Catholic churches of the Union of Utrecht and the Scandinavian Lutheran churches of the Porvoo Communion in Europe, the India-based Malankara Mar Thoma Syrian and Malabar Independent Syrian churches and the Philippine Independent Church, also known as the Aglipayan Church.

Historic episcopate
The churches of the Anglican Communion have traditionally held that ordination in the historic episcopate is a core element in the validity of clerical ordinations. The Roman Catholic Church, however, does not recognise Anglican orders (see Apostolicae curae). Some Eastern Orthodox churches have issued statements to the effect that Anglican orders could be accepted, yet have still reordained former Anglican clergy; other Eastern Orthodox churches have rejected Anglican orders altogether. Orthodox bishop Kallistos Ware explains this apparent discrepancy as follows:

"Anglican clergy who join the Orthodox Church are reordained; but [some Orthodox churches hold that] if Anglicanism and Orthodoxy were to reach full unity in the faith, perhaps such reordination might not be found necessary. It should be added, however, that a number of individual Orthodox theologians hold that under no circumstances would it be possible to recognise the validity of Anglican Orders."

title: Anglican Communion


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Arne Kaijser

Arne Kaijser (born 1950) is a professor emeritus of history of technology at the KTH Royal Institute of Technology in Stockholm, and a former president of the Society for the History of Technology.

Kaijser has published two books in Swedish: ''Stadens ljus. Etableringen av de första svenska gasverken and I fädrens spår. Den svenska infrastrukturens historiska utveckling och framtida utmaningar'', and has co-edited several anthologies. Kaijser is a member of the Royal Swedish Academy of Engineering Sciences since 2007 and also a member of the editorial board of two scientific journals: Journal of Urban Technology and Centaurus. Lately, he has been occupied with the history of Large Technical Systems.

title: Arne Kaijser


text:
Archipelago

An archipelago, sometimes called an island group or island chain, is a chain, cluster, or collection of islands, or sometimes a sea containing a small number of scattered islands.

Examples of archipelagos include: the Indonesian Archipelago, the Aleutian Islands, the Lakshadweep Islands, the Galápagos Islands, the Japanese archipelago, the Philippine Archipelago, the Maldives, the Balearic Islands, the Åland Islands, The Bahamas, the Aegean Islands, the Hawaiian Islands, the Canary Islands, Malta, the Azores, the Canadian Arctic Archipelago, the British Isles, the islands of the Archipelago Sea, and Shetland. Archipelagos are sometimes defined by political boundaries. For example, while they are geopolitically divided, the San Juan Islands and Gulf Islands geologically form part of a larger Gulf Archipelago.

Etymology
The word archipelago is derived from the Ancient Greek ἄρχι-(arkhi-, "chief") and πέλαγος (pélagos, "sea") through the Italian arcipelago. In antiquity, "Archipelago" (from Medieval Greek *ἀρχιπέλαγος and Latin archipelagus) was the proper name for the Aegean Sea. Later, usage shifted to refer to the Aegean Islands (since the sea has a large number of islands).

Geographic types
Archipelagos may be found isolated in large amounts of water or neighbouring a large land mass. For example, Scotland has more than 700 islands surrounding its mainland, which form an archipelago.

Archipelagos are often volcanic, forming along island arcs generated by subduction zones or hotspots, but may also be the result of erosion, deposition, and land elevation. Depending on their geological origin, islands forming archipelagos can be referred to as oceanic islands, continental fragments, or continental islands.

Oceanic islands
Oceanic islands are mainly of volcanic origin, and widely separated from any adjacent continent. The Hawaiian Islands and Galapagos Islands in the Pacific, and Mascarene Islands in the south Indian Ocean are examples.

Continental fragments
Continental fragments correspond to land masses that have separated from a continental mass due to tectonic displacement. The Farallon Islands off the coast of California are an example.

Continental archipelagos
Sets of islands formed close to the coast of a continent are considered continental archipelagos when they form part of the same continental shelf, when those islands are above-water extensions of the shelf. The islands of the Inside Passage off the coast of British Columbia and the Canadian Arctic Archipelago are examples.

Artificial archipelagos
Artificial archipelagos have been created in various countries for different purposes. Palm Islands and The World Islands off Dubai were or are being created for leisure and tourism purposes. Marker Wadden in the Netherlands is being built as a conservation area for birds and other wildlife.

Superlatives
The largest archipelago in the world by number of islands is the Archipelago Sea, which is part of Finland. There are approximately 40,000, mostly uninhabited, islands

The largest archipelagic state in the world by area, and by population, is Indonesia.

title: Archipelago