Aluminum is a winged metal
Aluminum (lat. Aluminum, chemical symbol Al, III group of the periodic system of Mendeleev, atomic number 13, atomic weight 26.9815) - soft, light, silvery-white metal, quickly oxidizing, specific density 2.7 g/cm³, melting point 660°C.
In terms of abundance in the earth's crust, aluminum ranks 3rd after oxygen and silicon among all atoms and 1st among metals. In nature, it is represented by only one stable nuclide, 27Al.
A number of radioactive isotopes of aluminum have been artificially obtained, the longest-lived is 26Al, which has a half-life of 720 thousand years.
Aluminum in nature
Aluminum is the most common metal on earth, and it ranks third among all elements in the earth's crust. It accounts for 8% of the composition of the earth's crust. Bauxite ore is currently the main raw material for aluminum production.
Every year from 80 to 90 million tons of bauxite ore are mined in the world. Almost 30% of this quantity is mined in Australia and another 15% in Jamaica. At the current level of global aluminum production, the discovered reserves of bauxite on earth are sufficient to meet the demand for aluminum for several hundred years.
Application of aluminum
Aluminum has the most versatile applications of all metals. It is widely used in transport engineering, for example, for the design of aircraft, ships, and cars.
In the chemical industry, aluminum is used as a reducing agent, in the construction industry for the manufacture of window frames and doors, and in the food industry for the manufacture of packaging materials.
In everyday life, it is used as a material for kitchen utensils and in the form of foil for storing food.
Biological effect of metal
Surprisingly, despite the wide distribution of aluminum in nature, this metal is practically not built into the biological chains of living beings. Moreover, aluminum compounds have a weak toxic effect on living organisms.
Aluminum salts, such as chlorides and nitrates, are harmful to the tissues of the human body, so recently people have begun to refuse to use aluminum cookware.
Aluminum can accumulate in the human body, so unnecessary contact with the winged metal should be avoided.
Source: https://www.allmetals.ru/metals/aluminium/
Features of aluminum metal: its properties, advantages and characteristics
Aluminum is the most abundant metal in the earth's crust and occurs as an isotope. Its active extraction is associated with a wide range of applications. Due to low thermal conductivity, resistance to corrosion, high refractoriness and heat resistance, not a single area of production can do without this metal.
The metal itself is white in color and chemically reactive. Reacting with air, an oxide film is formed on its surface, which protects it from moisture and other negative factors that act as irritants. This reaction not only acts as an advantage of the metal, but is also in some way a disadvantage, adjusting the casting process.
Aluminum production must take place without access to air, otherwise a mixture of aluminum and its oxides will be formed instead of pure metal.
The following discusses the advantages and disadvantages of enamelling, anodized and other types of aluminum, as well as its classification.
This video will introduce you to the features of aluminum:
Due to its structure and characteristics, aluminum has the following advantages:
- Light weight;
- Corrosion resistance;
- High sound absorption coefficient;
- Environmental Safety;
- Resistance to temperature changes;
- Durability;
- Possibility of adjusting characteristics due to impurities.
As for the disadvantages, we can only note the high cost compared to other metals. However, the advantages make this feature less significant.
Classification
Aluminum is rarely used in its pure form; in order to obtain the necessary functions and technical characteristics, special impurities are added to the metal. If the tensile strength of pure metal is 90 MPa, then by adding alloying components (magnesium, zinc, etc.) this figure can be increased to 700 MPa.
Such aluminum alloys can be divided into two groups:
- Deformable alloys. To produce them, the metal is initially poured into special ingots, which are then processed under high pressure using one of the methods.
- Casting alloys. They are characterized by a high silicon content and the need for casting into ready-made molds.
We will talk about the melting and boiling point of aluminum, other chemical properties and characteristics of the metal below.
Properties and characteristics
The physical properties of a given metal depend directly on its purity. If the composition of aluminum is as close as possible to unity, then the result is the maximum possible properties. That is why it is ideal for forging, stamping and other processing methods.
A distinctive feature of aluminum is the ability to use different types of welding. In addition, the metal has the following characteristics:
- Low density coefficient, which is 2.7 g/cm³. Its strength, which is also low, also depends on this indicator. It is for this reason that aluminum in its pure form is not used for structural purposes.
- High thermal conductivity coefficient. Pure metal at a temperature of 200°C has a thermal conductivity of 209 W/(m*K).
- The melting point of technical type aluminum is 657 °C, and that of pure aluminum is 660 °C.
- The specific heat capacity is 880 J/kg·K.
- Boiling point - 2500 °C.
Next, the structure and chemical composition of aluminum are considered.
Structure and composition
The structure of aluminum is represented by a cubic lattice of crystals. The minimum distance between two atoms is from 2.863Å. The crystal lattice is stable at temperature conditions from 4K to the immediate melting point. The presence of impurities has virtually no effect on the structure of aluminum.
In addition to pure aluminum, the composition may contain impurities of zinc, silicon, magnesium and other metals. Next, we will look at the production and use of aluminum based on its chemical and physical properties.
The video below will show you how to properly melt aluminum using a gas stove:
The technological process for producing this metal includes three stages:
- Obtaining alumina from primary raw materials (aluminium-containing ores).
- Creation of technical aluminum from the resulting alumina.
- The process of maximum metal purification.
Aluminum oxide is produced from alumina by electrolysis. The compound must be as pure as possible, since at this stage of its preparation it is very problematic to get rid of unnecessary impurities.
To obtain aluminum with a purity close to unity, it is necessary to organize several workshops for its processing, each of which will be responsible for a certain stage of production. That is why pure metal has a fairly high price, reaching up to $1,700 per 1 ton (1,000 kg of aluminum).
Technical characteristics and the ability to subject aluminum to various treatments have led to its widespread use. In particular, the metal is actively used in the following areas:
- Aircraft manufacturing;
- Automotive industry;
- Rocket Science;
- Production of tableware;
- Food industry;
- Shipbuilding;
- Microelectronics;
- Energy and much more.
Often, in the process of using aluminum, it is used in symbiosis with other metals, for example, iron, titanium, nickel, bronze, copper, etc. The features of aluminum, its technical characteristics and widespread use have made this metal extremely in demand. No modern industry can do without its use.
This video will tell you how to solder aluminum without a special flux:
Source: http://stroyres.net/metallicheskie/vidyi/tsvetnyie/alyuminiy/osobennosti-preimushhestva-i-harakteristiki.html
Analog of a diamond: the name of a similar stone and its properties, ways to distinguish it from a natural one
Diamonds are the most expensive gemstones. Jewelry with a shining crystal can cost several thousand dollars. Not everyone can afford to buy such jewelry, so in jewelry production, diamonds are often replaced with other natural and artificial minerals. Unfortunately, scammers often do this, passing off a cheap fake as an expensive diamond. What types of imitation diamonds are there and how to distinguish the original from the analogue?
Diamond analogues, their names, properties and appearance
A diamond is a stone unique in its properties. It is considered the hardest material in the earth's crust. Thanks to the cut, the ray of light inside the crystal is refracted and gives the stone an amazing shine. There are no minerals in the world that have the same characteristics; man has not yet been able to recreate diamonds in the laboratory. However, there are several minerals that are used as substitutes.
Natural stones
There are many minerals similar to diamonds in the earth's crust. Natural diamond substitutes used in jewelry:
- Rock crystal is a colorless, transparent silicon dioxide, a type of quartz. It is often found in the earth's crust, so jewelry with it is inexpensive.
- White sapphires are a variety of corundum, devoid of impurities, so instead of the usual blue color, the stone is transparent. In its hardness, sapphire is close to diamond. On the Mohs scale, the hardness of diamond is 10, and white sapphire is 9.
- Colorless topaz is a mineral from the aluminum silicate group. The most well-known colored varieties of topaz are golden, blue, and pink. The transparent mineral is in little demand, but can be used as a substitute for diamonds.
- Zircon is a mineral, zirconium orthosilicate. The transparent variety is free of impurities and has a strong diamond luster, which allows the stone to be used as a substitute.
- Goshenite is a transparent variety of beryl. Green beryls are called emeralds. Goshenite is inexpensive, but is also used for jewelry.
Goshenite
Artificial diamonds
Chemical laboratories have learned to create synthetic minerals with the desired properties. Names of substitutes:
- Cubic zirconia is a synthetic zirconium dioxide. Its refractive index is close to diamond, so the crystal is often used to imitate various precious stones. It is almost impossible to distinguish cubic zirconia from a diamond by eye.
- Carborundum is a chemical compound produced by sintering silica with carbon at high temperatures. The hardness is close to diamond - 9.5.
Carborundum
Areas of application of diamond analogues
Imitations of diamonds created by nature and human hands are used in jewelry to replace precious stones. However, due to their physical and chemical properties, these minerals have found wide application in industry and can replace superhard diamond crystals in various fields of production.
The table shows the areas of application of diamond analogues other than jewelry:
| Name of mineral | Origin | Scope of application |
| Rhinestone | Natural | Radio engineering, production of prisms, spectrographs, lenses |
| White sapphire, leucosapphire | Natural, artificial | Manufacturing of eye lenses, braces in dentistry, production of high-strength glass for windows, gadget screens |
| Zircon | Natural | Production of dental crowns, veneers |
| cubic zirconia | Artificial | Ceramic spraying in dentistry |
| Carborundum | Artificial | Production of abrasives, electronic devices, astronomical optics, steel, heating elements, use in nuclear energy |
Rhinestone
How to distinguish the original from the analogue?
It is difficult to distinguish a substitute from a natural diamond. Jewelers try to make the imitation so skillful that it is no different from a diamond.
First of all, when purchasing, you should ask for a quality certificate for the product; it should indicate what material the jewelry is made of. One of the main differences is the hardness of the crystal. If you run a natural diamond across the glass, a deep scratch will appear. Cubic zirconia, topaz, rock crystal and other minerals will leave only a small trace.
Zircon
To find out for sure which stone is inserted into a piece of jewelry, you will need the help of jewelers, gemologists or mineralogists. With the help of professional tools and chemical reagents, a specialist will be able to determine what kind of mineral is in front of him.
Source: https://moykamen.com/galereya/analog-brillianta.html
Aluminum is the most abundant metal in the earth's crust
- Aluminum is one of the most common elements in nature, exceeded only by oxygen and silicon, and among metals it ranks first in abundance. There is so much of it that experts estimate its mass fraction in the earth’s crust to be up to 8%. As a chemical element, aluminum is found in a huge number of minerals, for example, it is found in sapphires and rubies, in granite and feldspar, in emeralds and, of course, in bauxite - aluminum ore.
Properties of aluminum
Of the main physical properties of aluminum, it should be especially noted: - very low density, three times less than the density of steel, zinc and copper (aluminum is a light metal); - high electrical conductivity, the value of which is second only to copper and silver; - high thermal conductivity; - corrosion resistance ;—high ductility (soft metal);—reflective ability;—paramagnetism;—the ability to form alloys with other metals;—preservation of ductility and increased strength at very low temperatures;—non-toxicity.
Aluminum is easily processed by mechanical methods, it can be subjected to cold and hot processing, rolled into the thinnest foil and wire, and turned into powder. In its pure form, aluminum is a very active metal that reacts chemically with acids and alkalis, oxygen, carbon, nitrogen, and halogens , water and other substances.
Paradoxically, aluminum's outstanding corrosion resistance is based on the chemical reactivity of the metal. In air, aluminum is immediately covered with a film of Al2O3, which under normal conditions reliably protects the metal from any further reactions. Therefore, aluminum is practically never found in its native form, only in the form of compounds.
10 interesting facts about metals and their amazing properties
Metals are a group of chemical elements in the form of simple substances. They all have their own properties, according to which they can be divided into different groups.
The word “metal” itself came into Russian from Germany. At first it meant the same thing as “mineral, ore.” They began to separate concepts only after Lomonosov’s works.
The word has entered the language remarkably well, now everyone knows it. The most famous metals are probably gold, silver, mercury, copper and iron. But knowledge even about them is very incomplete. Nature always finds something to surprise us with.
In this article we will look at 10 interesting facts about metals.
10. Titanium is used as an implant
Implantation is a way to restore lost teeth.
Now this method is very common due to its speed and accessibility. It consists of the following: a rod is implanted into the jaw, which becomes a support for the new tooth. This very rod is made of titanium.
As a metal, it has high strength, and its elasticity is similar to human bone, so implantation is easier. Titanium is the very basis of a dental implant, which reduces the risk of bone destruction .
9. Silver has bactericidal properties
Silver was known to people even before our era. For some time it was even valued higher than gold. However, people are still learning about its various properties.
For example, the direct effect of ionic silver on bacteria is still debated. It has been proven that when bacteria and ions come into contact, the former die as a result of exposure.
Many theories have already been put forward, but the exact reasons for the death of microorganisms under the influence of silver are still unknown.
The ions of this metal cope well with the pathogens of typhoid, protea, diphtheria and others . Where silver does not kill bacteria, it may slow the germination of new spores and the spread of microorganisms.
8. Tantalum is widely used in prosthetics
Tantalum is an unusual metal that is quite rarely found in its pure form. For this reason it became very expensive.
He is difficult to obtain, so he was named after the hero of Greek myths. There Tantalus constantly tried to get at least a little food and water, but he still failed.
A chemist trying to obtain this metal in its pure form compared his work to tantalum flour. Despite this, tantalum has now found application in many areas.
It is very widespread in medicine because the human body does not reject it . It is used to produce plates for skulls, paper clips for connecting blood vessels, threads for replacing tendons and stitching together fibers. Sometimes used to make eye prostheses.
7. Aluminum is part of the earth's crust
Immediately after its discovery, aluminum was highly valued due to its similarity to silver. And extracting it in its pure form was not easy.
Scientists have already proven that this metal is widespread everywhere. Almost 8% of the earth's crust consists of it .
If we compare metals by the amount of their content in the earth's crust, it is second only to oxygen and silicon. But here’s an interesting fact: despite its prevalence, aluminum cannot be found in nature in its free form.
6. Mercury evaporates into the air
When people first discovered mercury, it was given the name "living silver." This is a very accurate definition of what mercury looks like.
The rare metal is a liquid, but it is also very heavy. The most common item where you can see mercury is an old thermometer. All parents forbid their children to touch it. And all because of the properties of mercury, which can evaporate in the air .
The vapors generated during evaporation are very toxic and can harm the human body. They penetrate inside, disrupt the composition and structure of proteins, which is why some processes begin to flow in the opposite direction, which entails poisoning and death.
But only large amounts of this metal cause death, more than in a regular thermometer. However, measures to eliminate the problem must be taken immediately in any case.
5. Tin is the most fusible metal
One metal that has already revealed almost all its secrets to people is tin. It has been known to mankind for a long time.
Before the discovery of the properties of iron, almost everything was made from an alloy of tin and copper: from weapons to jewelry. And this is understandable.
Tin is one of the most fusible metals . Its temperature is 232 - 240 degrees Celsius. Thus, only one requirement must be met - for molds it should not melt at temperatures up to 250 degrees. That's all, this metal has no more restrictions for melting, casting, soldering and other uses.
4. Iridium is the densest metal
Iridium is an interesting metal. It is found in the earth's crust even less frequently than gold and platinum. There is an assumption that its quantity is much larger, but it is located closer to the Earth’s core, out of reach.
Relative to the earth's crust, iridium is often found in meteorites. It is the densest and most refractory metal .
Its melting point is 2466 degrees Celsius. In terms of density, it is comparable only to osmium. They are almost equal, and the difference in numbers can be attributed to an error.
3. The Valcambi company produces ingots from expensive metals in the form of chocolate bars
Valcambi is an organization in Switzerland that has taken a very creative approach to the concept of ingots.
When they say the phrase “gold bars,” people always imagine beautiful shiny bricks stacked on top of each other in a pyramid. But the company decided to destroy this idea.
They make gold, silver, platinum and palladium bars in the form of chocolate bars . This was a wonderful gift idea.
Such an ingot can be broken into several small pieces (about 1 gram) and given as a gift to loved ones. Another use case is to pay for purchases in stores that accept this type of payment, of course.
2. Olympic medals are not gold at all.
Olympic gold medals are silver . In fact, the International Olympic Committee has declared that gold sports awards must be plated with just 6 grams of gold.
The rest of the medals may be silver. So, for example, if you study a medal from the London 2012 Olympic Games, the research results will be quite surprising. gold in a gold medal is only 1%, although all conditions are met.
1. More than 50% of the world's gold is found in Africa
For as long as humanity has existed, people have been drawn to gold. Finding a vein meant untold riches. For his sake they lied, stole, killed. But using all the methods possible to us, about 161 thousand tons of it have been found throughout history.
Most of this expensive metal was discovered in South Africa . But in reality this is not as much as it might seem at the very beginning. It is easier to present this fact differently.
If you melt all the gold found in the world into one large cube, its side will be only 20 meters. Half of this cube was found in Africa. Approximately every hour people take out a cube of iron of the same size from the ground. And all the gold in the world is worth about 9 trillion dollars.
Source: https://top10a.ru/interesnye-fakty-o-metallax.html
Aluminum in nature (7.5% in the earth's crust)
Around 1807, Davy, who was trying to carry out the electrolysis of alumina, gave the name to the metal supposed to contain it, Alumium.
Aluminum was first obtained by Hans Oersted in 1825 by the action of potassium amalgam on aluminum chloride followed by distillation of mercury. In 1827
Wöhler isolated aluminum metal in a more efficient way - by heating anhydrous aluminum chloride with potassium metal.
Being in nature, receiving:
In terms of prevalence in nature, it ranks 1st among metals and 3rd among elements, second only to oxygen and silicon. aluminum in the earth's crust, according to various researchers, ranges from 7.45% to 8.14% of the mass of the earth's crust. In nature, aluminum is found only in compounds (minerals).
Corundum: Al2O3 - belongs to the class of simple oxides, and sometimes forms transparent precious crystals - sapphire, and, with the addition of chromium, ruby.
Accumulates in placers. Bauxite: Al2O3*nH2O – sedimentary aluminum ores. Contain a harmful impurity – SiO2.
Bauxite serves as an important raw material for the production of aluminum, as well as paints and abrasives.
Kaolinite: Al2O3*2SiO2*2H2O – a mineral of the subclass of layered silicates, the main component of white, refractory, and porcelain clay.
The modern method for producing aluminum was developed independently by the American Charles Hall and the Frenchman Paul Héroux. It consists of dissolving aluminum oxide Al2O3 in molten cryolite Na3AlF3, followed by electrolysis using graphite electrodes.
This production method requires a lot of electricity, and therefore became popular only in the 20th century. To produce 1 ton of aluminum, 1.9 tons of alumina and 18 thousand kWh of electricity are required.
Physical properties:
The metal is silvery-white, lightweight, density 2.7 g/cm3, melting point 660°C, boiling point 2500°C. High ductility, rolled into thin sheets and even foil. Aluminum has high electrical and thermal conductivity and is highly reflective. Aluminum forms alloys with almost all metals.
Chemical properties:
Under normal conditions, aluminum is covered with a thin and durable oxide film and therefore does not react with classical oxidizing agents: with H2O (t°); O2, HNO3 (without heating). Thanks to this, aluminum is practically not subject to corrosion and is therefore widely in demand in modern industry.
However, when the oxide film is destroyed (for example, upon contact with solutions of ammonium salts NH4+, hot alkalis or as a result of amalgamation), aluminum acts as an active reducing metal.
Reacts easily with simple substances: oxygen, halogens: 2Al + 3Br2 = 2AlBr3 Aluminum reacts with other non-metals when heated:
2Al + 3S = Al2S3 2Al + N2 = 2AlN
Aluminum can only dissolve hydrogen, but does not react with it. With complex substances: aluminum reacts with alkalis (to form tetrahydroxyaluminates):
2Al + 2NaOH + 6H2O = 2Na[Al(OH)4] + 3H2
Easily dissolves in dilute and concentrated sulfuric acids:
2Al + 3H2SO4(dil) = Al2(SO4)3 + 3H2 2Al + 6H2SO4(conc) = Al2(SO4)3 + 3SO2 + 6H2O
Aluminum reduces metals from their oxides (aluminothermy): 8Al + 3Fe3O4 = 4Al2O3 + 9Fe
The most important connections:
Aluminum oxide , Al2O3: a white, hard, refractory substance.
Crystalline Al2O3 is chemically passive, amorphous is more active. Reacts slowly with acids and alkalis in solution, exhibiting amphoteric properties: Al2O3 + 6HCl(conc.) = 2AlCl3 + 3H2O Al2O3 + 2NaOH(conc.
) + 3H2O = 2Na[Al(OH)4] (NaAlO2 is formed in the alkali melt).
Aluminum hydroxide , Al(OH)3: white amorphous (gel-like) or crystalline. Practically insoluble in water. When heated, it decomposes step by step. It exhibits amphoteric, equally pronounced acidic and basic properties. When fused with NaOH, NaAlO2 is formed.
To obtain the Al(OH)3 precipitate, alkali is usually not used (due to the ease of transition of the precipitate into solution), but they act on aluminum salts with an ammonia solution - at room temperature Al(OH)3
Aluminum salts .
Aluminum salts and strong acids are highly soluble in water and undergo significant cation hydrolysis, creating a strongly acidic environment in which metals such as magnesium and zinc dissolve: Al3+ + H2O = AlOH2+ + H+ AlF3 fluoride and AlPO4 orthophosphate are insoluble in water, and salts of very weak acids, for example H2CO3, are not formed at all by precipitation from an aqueous solution.
Double aluminum salts are known - alum of the composition MAl(SO4)2*12H2O (M=Na+, K+, Rb+, Cs+, TI+, NH4+), the most common of them is potassium alum KAl(SO4)2*12H2O.
The dissolution of amphoteric hydroxides in alkaline solutions is considered as a process of formation of hydroxo salts (hydroxo complexes).
The existence of hydroxocomplexes [Al(OH)4(H2O)2] -, [Al(OH)6]3-, [Al(OH)5(H2O)]2-; of these, the first is the most durable. The coordination number of aluminum in these complexes is 6, i.e. aluminum is six-coordinated. Binary aluminum compounds Compounds with predominantly covalent bonds, for example Al2S3 sulfide and Al4C3 carbide, are completely decomposed by water:
Al2S3 + 6H2O = 2Al(OH)3 + 3H2S Al4C3 + 12H2O = 4Al(OH)3 + 3CH4
Application:
Widely used as a construction material. The main advantages of aluminum in this quality are lightness, malleability for stamping, corrosion resistance, and high thermal conductivity. Aluminum is an important component of many alloys (copper - aluminum bronze, magnesium, etc.) It is used in electrical engineering for the manufacture of wires and their shielding.
Aluminum is widely used in both thermal equipment and cryogenic technology. High reflectivity, combined with low cost and ease of deposition, makes aluminum an ideal material for making mirrors. Aluminum and its compounds are used in rocket technology as rocket fuel.
In the production of building materials as a gas-forming agent.
Source: https://storm24.media/news/44713
