aluminium (Al)

Element name: aluminum

Atomic weight of element: 26.98

Element type: metal

Atomic number: 13

Element symbol: Al

Chinese name of element: aluminum

English name of element: aluminum

Relative atomic mass: 26.98

Number of protons in the nucleus: 13

Number of Extranuclear Electrons: 13

Nuclear power number: 13

Proton mass: 2. 1749E-26

Proton relative mass: 13+38+0.

Period: 3

Number of families: IIIA

Molar mass: 27

Hydride: AlH3

Oxide: Al2O3

Chemical formula of the highest valence oxide: Al2O3

Density: 2.702

Melting point: 660.37

Boiling point: 2467.0

Peripheral electronic configuration: 3X23P 1

Extranuclear electron configurations: 2,8,3

Color and state: silvery white metal

Atomic radius: 1.82

Ordinary valence: +3

Discovery: Ernest and Willer.

Time and place of discovery: 1825 Denmark

Element source: the most abundant metal in the earth's crust, more than 7%.

Element uses: It can be used as structural materials for airplanes, vehicles, ships, ships and rockets. Pure aluminum can be used as EHV cable. Aluminum used as daily utensils is usually called "steel essence" and "steel grade"

Industrial method: electrolytic molten aluminum chloride.

Laboratory method: electrolytic molten aluminum chloride.

Other compounds: AlCl3- aluminum chloride NaAlO2- sodium metaaluminate Al(OH)3- aluminum hydroxide.

Introduction: Blue silvery white trivalent metallic element, with good ductility, toughness and [loud] sound, is famous for its light weight, good electrical and thermal conductivity, high reflectivity and oxidation resistance.

Discovered by: Weller Date of Discovery: 1827.

Discovery process:

1827, Germany weller heated potassium and aluminum trichloride to produce aluminum.

Element description:

A silvery shiny metal with a density of 2.702g/cm3, a melting point of 660.37℃ and a boiling point of 2467℃. Valence 3. It has good thermal conductivity, electrical conductivity and ductility, and its ionization energy is 5.986 eV. Although it is called active metal, it will form a dense oxide film on its surface in air, which makes it unable to continue to interact with oxygen and water. It can react with oxygen at high temperature and give off a lot of heat. Because of the high reaction heat, aluminum can replace metals in other oxides (aluminothermic method). For example, 8Al+3Fe3O4=4Al2O3+9Fe+795 kcal, aluminum can also react with nonmetals at high temperature, and can also be dissolved in acid or alkali to release hydrogen. It has no effect on water, sulfide, concentrated sulfuric acid, acetic acid of any concentration and all organic acids.

Element source:

Aluminum exists as a compound in various rocks or ores, such as feldspar, mica, Gaolingcheng, bauxite, alum and so on. Made of alumina and cryolite (Na3AlF6)*** by melting electrolysis.

Element usage:

Aluminum can replace metals in other oxides (aluminothermic method). Its alloy is light and tough, and it is a structural material for making airplanes, rockets and automobiles. Pure aluminum is widely used in cables. Widely used in making daily utensils.

Element auxiliary data:

The distribution of aluminum in the earth's crust is second only to oxygen and silicon among all chemical elements, and occupies the third and first place among all metal elements. However, aluminum was discovered late because of its strong oxidation ability and difficult reduction.

After Italian physicist Volt discovered the battery in 1800, during 1808 ~ 18 10, both British chemist David and Swedish chemist Bezirius tried to separate aluminum from bauxite by current, but both failed. On the other hand, Bezirius named this unattainable metal alumien. This is written by Latin alumni. In medieval Europe, this term is the general name of convergent alum, which refers to the mordant when dyeing cotton fabrics. Later, the Latin name of aluminum and the element symbol Al came from this.

1825 Danish chemist Oster published the process of making aluminum through experiments. 1827, German chemist Ulf repeated Oster's experiment and constantly improved the method of making aluminum. 1854, German chemist De Ville reduced aluminum chloride with sodium instead of potassium, and made aluminum into ingots.

Element symbol: Al English name: Aluminum Chinese name: aluminum

Relative atomic mass: 26.98 15 Ordinary valence: +3 Electronegativity: 1.6 1.

Peripheral electronic configuration: 3X23P 1 extranuclear electronic configuration: 2,8,3.

Isotope and radiation: Al-26 [730000y] * Al-27Al-28 [2.3m].

Electron affinity energy and energy: 48kJ mol-1.

The first ionization energy is 577.6kJ mol- 1, the second ionization energy is1817 kj mol-1,and the third ionization energy is 2745kJ mol- 1.

Element density: 2.702 g/cm3 Element melting point: 660.37℃ Element boiling point: 2467℃

Atomic radius: 1.82 angstrom ion radius: 0.5 1(+3) angstrom valence radius: 1. 18 angstrom.

Common compounds: Al2O3 AlCl3al2S3Nalo2al2 (SO4) 3al (OH) 3.

Aluminum, atomic number 13, atomic weight 26.38+0539. 1825, Danish scientist Oster reacted with potassium amalgam with anhydrous aluminum trichloride and evaporated mercury to obtain aluminum. 1854, DeVille reduced the molten salt of sodium chloride and aluminum chloride with metallic sodium to make metallic aluminum, which was exhibited at the Paris Expo in 1855. 1886, Hall and Elu respectively invented the molten salt method of electrolytic alumina and cryolite, making aluminum a practical metal. The content of aluminum in the crust is 8%, second only to oxygen and silicon. It is widely distributed in rocks, soil, animals and plants.

Aluminum is a silvery white light metal with a melting point of 660.37℃, a boiling point of 2467℃ and a density of 2.702 g/cm? . Aluminum is a face-centered cubic structure with good electrical and thermal conductivity; Pure aluminum is softer.

Aluminum is an active metal. In dry air, a dense oxide film with a thickness of about 50 angstroms is immediately formed on the surface of aluminum, so that aluminum will not be further oxidized and can be waterproof. But aluminum powder is very flammable when mixed with air; Molten aluminum can react violently with water; Many metal oxides can be reduced to corresponding metals at high temperature; Aluminum is amphoteric, that is, it is easily soluble in strong alkali and dilute acid.

Aluminum is widely used.

Is aluminum harmful to human health?

Millions of elderly people in the world suffer from Alzheimer's disease. Many scientists have found that Alzheimer's disease is closely related to aluminum through research. At the same time, it is also found that aluminum is harmful to the function and immune function of brain, heart, liver and kidney. Therefore, the World Health Organization officially recognized aluminum as a food pollutant in 1989 and controlled it. It is suggested that the allowable daily intake of aluminum for adults is 60 mg.

Judging from the current situation in China, if we don't pay attention to it, the aluminum intake will exceed this index. In addition to taking aluminum from aluminum hydroxide, metoclopramide, atropine aluminum salt, nicotinic acid aluminum salt, aspirin and other drugs, each person also takes 8 mg ~ 12 mg of aluminum from food every day. Due to the use of aluminum cookware and tableware, aluminum is dissolved in food and absorbed by about 4 mg. A large amount of aluminum also comes from food additives containing aluminum. Aluminum-containing food additives are often used in fried foods such as fritters and oil cakes. Baking powder, a food additive containing aluminum, is also commonly used in steamed buns, flower rolls, cakes and so on. According to the results of spot checks by relevant departments, the lead content per kilogram of oil cake exceeds 1000 mg. If you eat 50 g of this oil cake, it will exceed the aluminum intake allowed per person per day. Therefore, we should try to eat less fried food, use less leavening agent containing aluminum, and avoid using aluminum cookware and tableware.

A good partner of mankind-aluminum

First, the birth and development history of aluminum

1854, French chemist de Weil mixed bauxite, charcoal and salt, introduced chlorine gas and heated to obtain NaCl and AlCl3 double salts, and then melted the double salts with excessive sodium to obtain metallic aluminum. Aluminum is very precious at this time. It is said that at a banquet, French Emperor Charles Louis Napolé on Bonaparte used aluminum knives and forks alone, while others used silver tableware. At that time, the king of Thailand used an aluminum watch chain; 1955, a small piece of aluminum was exhibited at the national exposition in Paris. The label says, "Silver in Clay", which is placed next to the most precious jewelry. Until 1889, the Chemical Society of London gave Mendeleev vases and cups made of aluminum and gold as valuable gifts. 1886, Howell in the United States and Herrant in France independently electrolyzed the mixture of bauxite and cryolite to produce metallic aluminum, which laid the foundation for large-scale production of aluminum today.

In the historical process of nearly a century, the output of aluminum has risen sharply. In 1960s, aluminum surpassed copper in the world nonferrous metal production, ranking first. At this time, aluminum is not only owned by the royal family, but also used in many fields, from national defense, aerospace, electricity, communications, to daily necessities such as pots and pans. Its compounds are widely used, and different aluminum-containing compounds play an important role in medicine, organic synthesis, petroleum refining and so on.

Second, aluminum and its alloys

Pure aluminum is very soft, not tough, and has good ductility. It can be drawn into filaments and rolled into foil, and is widely used in manufacturing wires, cables, radio industries and packaging industries. Its conductivity is about two-thirds of that of copper, but its density is only one-third of that of copper. Therefore, compared with copper wire and aluminum wire with the same quality and length, the conductivity of aluminum is about twice as high as that of copper, and the price is lower. Therefore, high-voltage lines in the field are mostly made of aluminum, which saves a lot of costs and relieves the tension of copper materials.

The thermal conductivity of aluminum is three times that of iron. In industry, aluminum is often used to make various heat exchangers and heat dissipation materials, and many cookers used in families are also made of aluminum. Compared with iron, it is not easy to rust and prolongs the service life. Aluminum powder has silvery white luster and is often mixed with other substances as a coating, which is painted on the surface of iron products to protect iron products from corrosion and is beautiful. Because aluminum can emit dazzling white light and a lot of heat when burned in oxygen, it is often used to make some explosive mixtures, such as ammonium aluminum explosive.

In metallurgical industry, thermite is often used to melt refractory metals. For example, when aluminum powder and iron oxide powder are mixed together, they will react violently after being triggered, and are often used to weld railway tracks in traffic; Aluminum is often used as deoxidizer in steelmaking industry; Smooth aluminum plate has good reflective performance, and can be used to manufacture high-quality mirrors, condensing bowls, etc. Aluminum also has good sound absorption performance. According to this feature, some broadcast rooms and ceilings in modern buildings are made of aluminum. Pure aluminum is softer. 1906, German metallurgist Villm added a small amount of magnesium and copper to aluminum to make a tough aluminum alloy. Later, this patent was bought by the German Dura company, so aluminum is also called "Dura aluminum". In the development process of the next few decades, people developed a lot of aluminum alloys according to different needs, which played a very important role in many fields.

Adding a small amount of aluminum to some metals can greatly improve their properties. For example, bronze aluminum (containing 4% ~ 15% aluminum) has high-strength corrosion resistance, hardness close to that of low-carbon steel, and metallic luster that is not easy to blacken. It is often used in jewelry and construction industries, manufacturing machine parts and tools, pickling equipment and other equipment in contact with dilute sulfuric acid, hydrochloric acid and hydrofluoric acid. Making brushes and clamping handles for electric welding machines; Heavy gear and worm wheel, metal forming mold, machine tool guide rail, non-spark tool, non-magnetic chain, pressure vessel, heat exchanger, compressor blade, ship propeller and anchor, etc. Adding magnesium to aluminum produces aluminum-magnesium alloy, which is much harder than pure magnesium and aluminum, and retains the characteristics of light weight, and is often used to manufacture aircraft fuselage and rocket body; Make doors and windows to beautify the living environment; Build ships.

Aluminizing is one of the chemical heat treatment methods of steel. A high-temperature resistant alumina film is formed on the surface of ordinary carbon steel or cast iron to protect the iron inside. Aluminum is a very important metal, however, many aluminum-containing compounds are also very important to human beings.

Three. Aluminum-containing compound

The content of aluminum in the earth's crust is higher than that of silicon and oxygen, ranking third, mainly existing in aluminosilicate ores, bauxite and cryolite. Alumina is a white amorphous powder with many variants, among which α-A 12O3 and β-Al2O3 are the most common. Corundum, which exists in nature, belongs to α-Al2O3. Its hardness is second only to that of diamond, with high melting point and acid and alkali resistance. It is usually used to make some bearings, abrasives and refractories. Such as corundum crucible, can withstand the high temperature of 1800℃. Corundum has many colors because it contains different impurities. For example, a trace of Cr(III) is red, which is called ruby; Sapphire containing Fe(II), Fe(III) or Ti(IV) is called sapphire.

β-A 12O3 is a porous substance with a surface area of several hundred square meters per gram. Also called activated alumina, it can adsorb many kinds of gas and liquid molecules such as water vapor, and is often used as adsorbent, catalyst carrier and desiccant. It is also used as raw material for industrial aluminum smelting.

Aluminum hydroxide can be used to prepare aluminum salts, adsorbents, mordants and ion exchangers, and can also be used as raw materials for porcelain glazes, refractories, fireproof fabrics and so on. Its glue solution and thousand glue are used as acidic drugs in medicine, which have the functions of neutralizing gastric acid and treating ulcers, and are used to treat gastric and duodenal ulcers and hyperacidity.

Sodium metaaluminate is often used in printing and dyeing fabrics, producing lake blue dye, making wool glass rot, soap and hardened building stone. In addition, it is also a good water softener, filler for papermaking, water purifier and polishing agent for rayon.

Aluminum trichloride is a commonly used catalyst in petroleum industry and organic synthesis. For example, the alkylation reaction of aromatic hydrocarbons, also known as Friedel-Crafts alkylation reaction, generates electrophilic substitution between aromatic hydrocarbons and halogenated hydrocarbons (or olefins and alcohols) under the catalysis of anhydrous aluminum trichloride, resulting in alkyl substituents of aromatic hydrocarbons. Aluminum chloride hexahydrate can be used to prepare deodorizers, safe disinfectants and petroleum refining.

Aluminum bromide is a common catalyst for organic synthesis and isomerization.

Aluminum phosphide will emit highly toxic phosphine gas when it is wet or acid, which can poison pests. It is used as a fumigant to kill pests in warehouse in agriculture.

Aluminum sulfate is often used as filler, mordant, water purifying agent and fire extinguishing agent, petroleum purifying agent and decoloring agent in papermaking, and is also used to make precipitated pigments, fireproof cloth and medicines.

Cryolite, namely sodium hexafluoroaluminate, is often used as an insecticide in agriculture; White opacifier used for making glass and enamel in silicate industry.

Alum extracted from alunite by heating is an important water purifying agent and mordant, which is used as an astringent in medicine. Aluminum nitrate can be used for tanning and making white thermoelectric wires, and can also be used as mordant. Aluminum silicate is often used to make pigments for glass, ceramics and paints, as well as fillers for paints, rubbers and plastics. Silica-alumina gel has hygroscopicity and is often used as a catalyst carrier for petroleum catalytic cracking or other organic synthesis.

In the carboxylate of aluminum; Aluminum dicarboxylate and aluminium triformate are commonly used as mordants, waterproofing agents and fungicides. Aluminum diacetate is not only used as mordant, but also used as sword collector and disinfectant, and also used in embalming solution for corpses. Aluminum triacetate is used to make waterproof and fireproof fabrics and lakes; Drugs (mouthwash, astringent, preservative, etc. ) and used as mordant. ; Aluminum octadecanoate (aluminum stearate) is often used as anti-precipitation agent for paint, waterproof agent for fabric, thickener for lubricating oil, antirust oil for tools, heat-resistant stabilizer for PVC plastics, etc. Aluminum oleate is not only used as a waterproof agent for fabrics and a thickener for lubricating oil, but also as a drier for paints and a lubricant for plastic products.

Sucralfate, also known as Weikuining, is an alkaline aluminum salt of sucrose sulfate. Can be combined with pepsin, directly inhibit proteolytic activity, and has a lasting effect. It can also form a protective film, which has a strong protective effect on gastric mucosa, helps mucosal regeneration and promotes ulcer healing, and has low toxicity. It is a good therapeutic agent for gastrointestinal ulcer.

In recent years, people have developed some new aluminum-containing compounds, such as alkyl aluminum. With the development of science, people will make better use of aluminum and its compounds for the benefit of mankind.

Fourth, the harm of "aluminum"

Improper use of aluminum can also produce some side effects. It is reported that aluminum salt may cause memory loss. A private research team in Australia said: Excessive use of aluminum salt to purify water may lead to brain damage and severe memory loss, which is a unique symptom of Alzheimer's disease. The researchers' experiments on mice show that the trace aluminum mixed in drinking water enters the brain of mice and gradually accumulates there. After giving them a glass of water treated with aluminum salt, the aluminum content in their brains reached a measurable level. !

According to the regulations of the World Health Organization, the daily intake of aluminum should not exceed 65,438+0 mg per kilogram of body weight. Under normal circumstances, a person's daily intake of aluminum will never exceed this amount. However, drink water purified by aluminum salt and eat food containing aluminum salt, such as fried dough sticks, vermicelli, bean jelly, oil cakes, canned soft drinks and so on. Or eating aluminum pot fried rice will increase people's intake of aluminum, thus

The harm of aluminum and its compounds to human beings cannot be compared with its contribution. As long as people pay attention to it, it will play a more important role in human society.