Chemical symbol for the element silicon. Silicon in nature (25.8% in the Earth's crust). What threatens excess silicon

physical properties. Silicon is fragile. When heated above 800 ° C, its plasticity increases. It is resistant to acids. In an acidic environment, it is covered with an insoluble oxide film and passivated.

The microelement is transparent to infrared radiation, starting from a wavelength of 1.1 microns.

Chemical properties. Silicon interacts:

• with halogens (fluorine) with the manifestation of reducing properties: Si + 2F2 = SiF4. It reacts with hydrogen chloride at 300°C, with hydrogen bromide at 500°C;
• with chlorine when heated to 400–600°C: Si + 2Cl2 = SiCl4;
• with oxygen when heated to 400–600°C: Si + O2 = SiO2;
• with other non-metals. At a temperature of 2000 ° C, it reacts with carbon (Si + C = SiC) and boron (Si + 3B = B3Si);
• with nitrogen at a temperature of 1000 ° C: 3Si + 2N2 = Si3N4;
• with metals to form silicides: 2Ca + Si = Ca2Si;
• with acids - only with a mixture of hydrofluoric and nitric acids: 3Si + 4HNO3 + 18HF = 3H2 + 4NO + 8H2O;
• with lye. Silicon dissolves and silicate and hydrogen are formed: Si + 2NaOH + H2O = Na2SiO3 + H2.

Does not interact with hydrogen.

Interaction in the body with vitamins and minerals

Silicon interacts with vitamins, and. The combination of cereals with citrus fruits and green vegetables is considered the most beneficial.

Silicon is involved in the fight against free radicals. Interacting with heavy metals (lead), the trace element forms stable compounds. They are excreted by the genitourinary system. The same thing happens with slags and toxic substances.

Silicon improves the absorption of iron (Fe) and calcium (Ca), cobalt (Cb), manganese (Mn), fluorine (F).

A decrease in the concentration of silicon in the connective tissue leads to vascular damage, atherosclerosis, and a violation of the strength of bone tissue.

The role of silicon in the occurrence and course of various diseases

With a lack of silicon in the body, the concentration of cholesterol in the blood increases. Because of this, cholesterol plaques are formed, the outflow worsens.

When silicon is consumed less than 20 mg per day, immunity weakens. Allergic rashes appear, the skin becomes dry and flaky, a fungus develops.

The hair becomes thinner, the scalp flakes and itches. The nail plates are deformed.

Working capacity and mental state worsen due to impaired blood outflow and saturation of the brain with oxygen.

With a decrease in the amount of silicon in the body to 1.2-1.6%, it is fraught with the occurrence of a stroke, heart attack, diabetes mellitus, hepatitis virus and oncology.

An excess of silicon leads to the deposition of salts in the urinary tract and joints, fibrosis and pathologies of blood vessels. In the worst case scenario, the liver enlarges, the limbs swell, the skin turns blue, and shortness of breath appears.

Functional potential of silicon

The main task of silicon in the body is the formation of bone, cartilage tissue and vessel walls. 90% of the mineral is found in connective and bone tissue, lymph nodes, thyroid gland, hair and skin. However, the functional potential of the chemical element is not limited to this. Thanks to silicon:

• bones and ligaments are strengthened. The more minerals in the first one, the stronger it is. A decrease in the concentration of silicon in bone tissue is fraught with osteoporosis and atherosclerosis. For cartilage, the synthesis of glycosaminoglycans is important;
• prevents degeneration of the intervertebral discs. The latter consist of plates of cartilaginous tissue. The less silicon, the faster the plate wears out. If a crack forms in it, cerebrospinal fluid will begin to flow out. This is fraught with protrusions and hernia;
• bone tissue is restored. Bones, ligaments and tendons grow together very difficult and long;
• improves the condition of the skin, nails and hair. They contain the highest concentration of a chemical element. Dry and flaky skin, brittle and dull hair, exfoliating nails are signs of silicon deficiency;
• metabolism stabilizes. Thanks to silicon, three-quarters of 70% of the chemical elements are absorbed. The mineral is involved in protein and carbohydrate metabolism;
• immunity is strengthened. Thanks to silicon, phagocytosis is accelerated - the formation of special cells of the immune system. Their main function is the breakdown of foreign protein structures. If a viral infection enters the body, phagocytes envelop the enemy and destroy it;
• removes heavy metals and toxins. Silicon oxide reacts with them, converts them into compounds that are neutral for the body, which are excreted in the urine;
• the walls of blood vessels, heart valves, the shell of the organs of the gastrointestinal tract are strengthened. The basis of the vessel wall is elastin, which is synthesized using silicon;
• the permeability of the walls of blood vessels decreases, the signs of varicose veins, thrombophlebitis and vasculitis decrease;
• cancer is prevented. The antioxidant properties of vitamins C, A, E are enhanced by interaction with silicon. It is easier for the body to fight free radicals;
• brain diseases are prevented. With a lack of silicon, the walls of blood vessels become softer, they poorly transport blood to the brain, which leads to hypoxia - oxygen starvation, due to which the brain does not function at full capacity. Brain neurons cannot give and receive commands without silicon. As a result, the motor skills of movements are disturbed, the vessels narrow, the head hurts and feels dizzy, and the state of health worsens.

Sources of silicon

Category	Product	Approximate silicon content
Vegetable oil	Cedar, sesame, mustard, almond, olive, peanut, pumpkin, linseed, soy
Animal oils	Lamb, beef, pork fat, lard, margarine, butter. Fish: flounder, halibut, chinook salmon	Insignificant, after processing silicon is absent
Juice	Grape, pear, cranberry	In a glass - 24% of the daily requirement of a microelement
nuts	Walnuts, hazelnuts, pistachios, sunflower seeds	In a handful of nuts from 12 to 100% of the daily requirement. The most silicon is in walnuts and hazelnuts (100% in 50 g), the least in pistachios (25% in 50 g)
Cereals	Brown rice, oatmeal, millet, wheat bran, corn, barley	A serving of porridge (200 g) contains the daily requirement of silicon
Vegetables	White cabbage, onions, celery, cucumbers, carrots, spinach, potatoes, radishes, beets. As well as tomatoes, peppers, rhubarb; beans, green beans and soy
Fruits and berries	Apricots, bananas, apples; strawberry, cherry, plum	In 200 g of fruits - up to 40% of the daily intake of silicon, in the same amount of berries - up to 30%
Dried fruits	Dates, figs, raisins
Dairy	Sour milk, kefir, eggs
Meat and seafood	Chicken, beef; seaweed, seaweed

• brown rice - 1240;
• oatmeal - 1000;
• millet - 754;
• barley - 600;
• soybeans - 177;
• buckwheat - 120;
• beans - 92;
• Peas - 83;
• Jerusalem artichoke - 80;
• Corn - 60;
• Hazelnut - 51;
• Spinach - 42;
• Ryazhenka - 34;
• Parsley - 31;
• Cauliflower - 24;
• Green leaf lettuce - 18;
• Peach - 10;
• Honeysuckle - 10.

Advice! Do you want to quickly replenish silicon reserves in the body? Forget meat with a side dish. The meat itself, although it contains a sufficient amount of silicon (30-50 mg per 100 g), prevents its absorption from other products. Separate food is the opposite. Combine brown rice, barley, millet, millet, buckwheat with vegetables and fruits. Arrange “fasting” days on apricots, pears and cherries

Combination with other nutrients

Avoid combining silicon with aluminum. The action of the latter is opposite to the action of silicon.

Silicon, together with other trace elements, is involved in the chemical reactions of the synthesis of collagen and elastin, which are part of the connective tissue of the skin, hair and nails.

Silicon enhances the antioxidant properties of vitamins C, A, E. The latter fight free radicals that cause cancer.

To prevent cancer, eat together such products (described in the table)

Foods rich in vitamin A:	Foods rich in vitamin C:	Foods rich in vitamin E:
carrots, parsley, sorrel and mountain ash; fresh green peas, spinach; peas, lettuce leaves; pumpkin, tomatoes, peach, apricot; white cabbage, green beans, blue plum, blackberry; red pepper, potatoes, green onions; wild rose, sea buckthorn, prunes; lentils, soybeans, apples; gourds; nettle, peppermint	sea ​​buckthorn berries, strawberries, black currants; citrus fruits, horseradish; strawberry, pineapple; banana, cherry; white cabbage broccoli, Brussels sprouts, sauerkraut; green young onion; raspberry, mango; green pepper, radish, spinach	cabbage, tomatoes, celery root, pumpkin; greens, sweet peppers, peas; carrots, corn; raspberries, blueberries, various dried fruits; blackcurrant, wild rose (fresh), plum; sesame, poppy, barley, oats, legumes

Silicon oxide interacts in the body with heavy metals (lead) and toxins. As a result of a chemical reaction, stable compounds are formed, which are excreted from the body by the kidneys.

Daily rate

The daily intake of silicon (listed below) is calculated for adults only. Tolerable upper intake levels for silicon for children and adolescents have not been established.

• Children under 6 months and after 7 months are absent.

• From 1 to 13 years old - none.
• Adolescents (male and female) - none.
• Adults - 20-50 mg.

When using silicon-containing preparations (Atoxil), the daily dosage in children over 7 years old and adults is 12 g. The maximum dose of the drug is 24 grams per day. For children from one year to 7 years - 150-200 mg of the drug per kilogram of body weight.

Silicon deficiency and excess

Silicon deficiency can be caused by:

The lack of silicon in the body is dangerous in the following condition:

• high concentration of cholesterol in the blood. Cholesterol clogs the blood vessels (zolesterol "plaques" are formed), the blood becomes more viscous and its outflow worsens;
• predisposition to fungal diseases. The less silicon, the weaker the immune system. When a viral infection enters the body, phagocytes (special cells of the immune system) are produced in insufficient quantities;
• dandruff, hair loss and thinning hair. The elasticity of hair and skin is the merit of elastin and collagen, which are synthesized due to silicon. Its deficiency affects the condition of the skin, hair and nails;
• mood swings. Not only working capacity, but also the mental state of a person depends on the saturation of the brain with oxygen. Due to the weakened walls of blood vessels, blood does not flow well to the brain. There is not enough oxygen to perform the usual mental operations. Mood swings and deterioration in performance are the result of a lack of silicon. The same thing happens when the weather changes;
• cardiovascular diseases. The reason is the same - weakened walls of blood vessels;
• diabetes mellitus. The reason is an increase in the concentration of glucose in the blood and the inability of the body to reduce it.

• from 1.2 to 4.7% - stroke and heart attack;
• 1.4% or less - diabetes mellitus;
• 1.6% or less - hepatitis virus;
• 1.3% - oncological diseases.

Advice! Silicon is involved in all types of exchange. Stored in the walls of blood vessels, the microelement protects them from the penetration of fats into the blood plasma and blocks the bloodstream.

Increase the amount of silicon-containing foods in your diet during:

• physical and emotional fatigue. A portion of cereals for breakfast, a large plate of green salad for lunch and a glass of fermented baked milk or kefir before going to bed guarantee a boost of energy;
• pregnancy and breastfeeding The immunity of the baby and mother depends on the correct diet. 20-50 mg of silicon per day will make the bones strong and the skin elastic;
• preparation for the competition. The more energy costs, the more silicon-containing foods should be in the diet. They will prevent fragility of bones and sprain of ligaments and tendons;
• puberty. Pain in the knees (Schlater's disease) is common. Bone cells divide faster than connective cells. The latter not only maintains the bone in an anatomically correct position, but also protects against mechanical damage. Cranberries, walnuts and pears are a great snack for a teenager.

If the condition of the skin, hair and nails is unsatisfactory, lean on cereals and juices. Grape juice for tomorrow, cranberry juice for lunch and pear juice for dinner are the first step to elastic and toned skin.

What threatens excess silicon

It is impossible to get sick due to an excess of silicon in the diet, but residents of areas with a high content of silicon in soil or water are at risk.

Due to the high concentration of silicon in the body:

• salts are deposited in the urinary tract, joints and other organs;
• fibrosis develops in the blood vessels and throughout the body as a whole. Symptoms: rapid breathing with light exertion, a decrease in lung capacity, low blood pressure;
• the right ventricle expands and hypertrophies ("cor pulmonale");
• the liver increases, the limbs swell, the skin turns blue;
• irritability increases, asthenic syndrome develops;
• increased risk of upper respiratory tract infections. The most common of these is silicosis. The disease develops due to the inhalation of dust containing silicon dioxide, and proceeds in a chronic form. As the disease progresses, connective tissue grows in the patient's lungs. Normal gas exchange is disturbed, and against its background, tuberculosis, emphysema, or lung cancer develop.

At risk are workers in mines, foundries, manufacturers of refractory materials and ceramic products. The disease is signaled by shortness of breath, shortness of breath and cough. Symptoms are aggravated by physical exertion. Porcelain and faience, glass production, deposits of ores of non-ferrous and precious metals, sandblasting of castings are potentially dangerous objects.

An excess of silicon is evidenced by a decrease and increase in body temperature, depression, general fatigue and drowsiness.

With such signs, include carrots, beets, potatoes, Jerusalem artichokes, as well as apricots, cherries, bananas and strawberries in the diet.

Products containing silicon

Despite the fact that the body of an adult contains 1-2 g of silicon, an additional portion does not hurt. Per day, with food and water, an adult consumes about 3.5 mg of silicon. An adult spends three times more on the main metabolism - about 9 mg. The reasons for the increased use of silicon are poor ecology, oxidative processes that provoke the formation of free radicals, and stress. You can’t do without silicon-containing products alone - stock up on drugs or medicinal plants.

The record holders for the content of silicon are juniper, horsetail, tansy, wormwood, ginkgo biloba. As well as field chamomile, thyme, Chinese walnut and eucalyptus.

Silicon deficiency can be filled with silicon water. One of the properties of a trace element is the structuring of water molecules. Such water is not suitable for the life of pathogenic microorganisms, protozoa, fungi, toxins and foreign chemical elements.

Silicon water in taste and freshness resembles melted water.

To purify and enrich water with silicon at home, you must:

• buy flint pebbles in a pharmacy store - the smaller, the better (the larger the area of ​​\u200b\u200bcontact between flint and water);
• put in water at the rate of 50 g of stones per 3 liters of water;
• infuse water in a glass bowl at room temperature in a dark place for 3-4 days. The longer the water is infused, the more pronounced the therapeutic effect;
• pour the prepared water into another container, leaving the bottom layer 3–4 cm deep (it cannot be used due to the accumulation of toxins).
• in a sealed container, water is stored for up to one and a half years.
• You can drink silicon water in any amount for the prevention of atherosclerosis, hypertension and urolithiasis, skin pathology and diabetes, infectious and oncological diseases, varicose veins and even neuropsychiatric diseases.

Atoxil (Atoxil). The active substance of Atoxil is silicon dioxide.

Release form:

• powder for suspension preparation;
• bottles of 12 g of the drug;
• vials of 10 mg of the drug;
• 2 g sachets, 20 sachets per pack.

Pharmachologic effect. It acts as an enterosorbent, has a wound-healing, anti-allergic, antimicrobial, bacteriostatic and detoxifying effect.

In the organs of the gastrointestinal tract, the drug absorbs exogenous and endogenous toxins (bacterial and food allergens, endotoxins of microorganisms, toxic substances) and removes them.

Accelerates the transport of toxins from the blood, lymph and tissues to the digestive tract.

Indications: diarrhea, salmonellosis, viral hepatitis A and B, allergic diseases (diathesis, atopic dermatitis), burns, trophic ulcers, purulent wounds.

It is used for kidney diseases, enterocolitis, toxic hepatitis, liver cirrhosis, hepatocholecystitis, drug and alcohol intoxication, skin diseases (eczema, dermatitis, neurodermatitis), intoxication with purulent-septic processes and burn disease.

How to apply:

• Bottle. Open the bottle (bottle) with the powder, add to the 250 ml mark in clean drinking water, shake until smooth.
• Sachet. Dissolve 1-2 sachets in 100-150 ml of clean drinking water. Take one hour before meals or medications.

The duration of treatment of acute intestinal infections is 3-5 days. The course of therapy is up to 15 days. In the treatment of viral hepatitis - 7-10 days.

Side effects effects: constipation.

Contraindications: exacerbation of peptic ulcer of the duodenum and stomach, erosion and ulcers of the mucous membrane of the large and small intestines, intestinal obstruction, hypersensitivity to silicon dioxide.

The drug is not prescribed for children under one year old, pregnant and breastfeeding.

Interaction with drugs:

• with Acetylsalicylic acid (Aspirin) - increased platelet disaggregation;
• with Simvastatin and Nicotinic acid - a decrease in the blood levels of atherogenic fractions of lipid spectrum indicators and an increase in the level of VP lipoproteins and cholesterol;
• with antiseptics (Trifuran, Furacillin, Chlorhexidine, Bifuran, etc.) - increasing the effectiveness of therapy for purulent-inflammatory processes.

2349.85°C (2623 K)

Oud. heat of fusion

50.6 kJ/mol

Oud. heat of evaporation

383 kJ/mol

Molar heat capacity The crystal lattice of a simple substance Lattice structure

cubic, diamond

Lattice parameters Debye temperature Other characteristics Thermal conductivity

(300 K) 149 W/(m K)

Emission spectrum

14
3s 2 3p 2

origin of name

Most often, silicon occurs in nature in the form of silica - compounds based on silicon dioxide (IV) SiO 2 (about 12% of the mass of the earth's crust). The main minerals and rocks formed by silica are sand (river and quartz), quartz and quartzites, flint, feldspars. The second most common group of silicon compounds in nature are silicates and aluminosilicates.

Isolated facts of finding pure silicon in native form are noted.

Receipt

Free silicon is obtained by calcining fine white sand (silicon dioxide) with magnesium:

$\backslash mathsf(SiO\_2+2Mg\; \backslash \; \backslash rightarrow\; \backslash \; 2MgO+Si)$

This creates amorphous silicon, having the appearance of a brown powder.

In industry, silicon of technical purity is obtained by reducing the SiO 2 melt with coke at a temperature of about 1800 ° C in ore-thermal shaft-type furnaces. The purity of silicon obtained in this way can reach 99.9% (the main impurities are carbon and metals).

Further purification of silicon from impurities is possible.

• Cleaning in the laboratory can be carried out by preliminary obtaining magnesium silicide Mg 2 Si. Further, gaseous monosilane SiH 4 is obtained from magnesium silicide using hydrochloric or acetic acid. Monosilane is purified by distillation, sorption, and other methods, and then decomposed into silicon and hydrogen at a temperature of about 1000 °C.
• Purification of silicon on an industrial scale is carried out by direct chlorination of silicon. In this case, compounds of the composition SiCl 4 , SiHCl 3 and SiH 2 Cl 2 are formed. They are purified from impurities in various ways (as a rule, by distillation and disproportionation) and, at the final stage, are reduced with pure hydrogen at temperatures from 900 to 1100 ° C.
• Cheaper, cleaner, and more efficient industrial silicon purification technologies are being developed. For 2010, these include silicon purification technologies using fluorine (instead of chlorine); technologies involving the distillation of silicon monoxide; technologies based on the etching of impurities concentrating at intergranular boundaries.

The content of impurities in post-purified silicon can be reduced to 10 −8 -10 −6 wt %. In more detail, the issues of obtaining ultrapure silicon are discussed in the article Polycrystalline silicon.

The method for obtaining silicon in its pure form was developed by Nikolai Nikolaevich Beketov.

Physical Properties

The crystal lattice of silicon is a cubic face-centered diamond type, parameter a = 0.54307 nm (other polymorphic modifications of silicon were also obtained at high pressures), but due to the longer bond length between Si-Si atoms compared to the C-C bond length, the hardness of silicon is significantly less than a diamond. Silicon is brittle, only when heated above 800 °C does it become plastic. It is transparent to infrared radiation from a wavelength of 1.1 µm. The intrinsic concentration of charge carriers is 5.81·10 15 m −3 (for a temperature of 300 K).

Electrophysical properties

Elemental silicon in single-crystal form is an indirect-gap semiconductor. The band gap at room temperature is 1.12 eV, and at T = 0 K - 1.21 eV. The concentration of intrinsic charge carriers in silicon under normal conditions is about 1.5·10 10 cm −3 .

The electrophysical properties of crystalline silicon are greatly influenced by the impurities contained in it. To obtain silicon crystals with hole conductivity, atoms of group III elements, such as boron, aluminum, gallium, indium, are introduced into silicon. To obtain silicon crystals with electronic conductivity, atoms of group V elements, such as phosphorus, arsenic, antimony, are introduced into silicon.

When creating electronic devices based on silicon, the near-surface layer of a single crystal (up to tens of microns thick) is mainly used, so the quality of the crystal surface can have a significant impact on the electrical properties of silicon and, accordingly, on the properties of the created electronic device. When creating some devices, the technology that modifies the surface of a single crystal is used, for example, treatment of the silicon surface with various chemical reagents and its irradiation.

Chemical properties

Like carbon atoms, silicon atoms are characterized by the state of sp 3 -hybridization of orbitals. In connection with hybridization, pure crystalline silicon forms a diamond-like lattice in which silicon is tetravalent. In compounds, silicon usually also manifests itself as a tetravalent element with an oxidation state of +4 or -4. There are divalent silicon compounds, for example, silicon oxide (II) - SiO.

Under normal conditions, silicon is chemically inactive and actively reacts only with gaseous fluorine, with the formation of volatile silicon tetrafluoride SiF 4 . Such "inactivity" of silicon is associated with the passivation of the surface by a nanoscale layer of silicon dioxide, which is immediately formed in the presence of oxygen, air or water (water vapor).

oxygen to form SiO 2 dioxide, the process is accompanied by an increase in the thickness of the dioxide layer on the surface, the rate of the oxidation process is limited by the diffusion of atomic oxygen through the dioxide film.

When heated to temperatures above 400-500 ° C, silicon reacts with chlorine, bromine and iodine - with the formation of the corresponding easily volatile tetrahalides SiHal 4 and, possibly, halides of a more complex composition.

Compounds of metals with silicon - silicides - are widely used in industry (for example, electronic and atomic) materials with a wide range of useful chemical, electrical and nuclear properties (resistance to oxidation, neutrons, etc.). Silicides of a number of elements are important thermoelectric materials.

Silicon compounds serve as the basis for the production of glass and cement. The silicate industry is engaged in the production of glass and cement. It also produces silicate ceramics - brick, porcelain, faience and products from them.

Silicate glue is widely known, used in construction as a desiccant, and in pyrotechnics and in everyday life for gluing paper.

Silicone oils and silicones, materials based on organosilicon compounds, have become widespread.

Biological role

For some organisms, silicon is an essential nutrient. It is part of the supporting structures in plants and skeletal structures in animals. In large quantities, silicon is concentrated by marine organisms - diatoms, radiolarians, sponges. Horsetails and cereals concentrate large amounts of silicon, primarily the Bamboo and Rice subfamilies, including sowing rice. Human muscle tissue contains (1-2) 10 -2% silicon, bone tissue - 17 10 -4%, blood - 3.9 mg / l. With food, up to 1 g of silicon enters the human body daily.

The norms of maximum permissible concentrations for silicon are tied to the content of silicon dioxide dust in the air. This is due to the peculiarities of silicon chemistry:

• Pure silicon, as well as silicon carbide, in contact with water or atmospheric oxygen forms an impermeable film of silicon dioxide (SiO 2) on the surface, which passivates the surface;
• Many organosilicon compounds in contact with atmospheric oxygen and water vapor are oxidized or hydrolyzed, eventually forming silicon dioxide;
• Silicon monoxide (SiO) in air is capable (sometimes with an explosion) of additional oxidation to highly dispersed silicon dioxide.

Silicon dioxide under normal conditions is always a solid bio-inert, non-degradable substance, prone to the formation of dust, consisting of particles with sharp cutting edges. The harmful effect of silicon dioxide and most silicides and silicates is based on the irritating and fibrogenic effect, on the accumulation of a substance in the lung tissue, which causes a serious illness - silicosis. Dust respirators are used to protect the respiratory organs from dust particles. However, even when using personal protective equipment for the nasopharynx, the throat of people who systematically work in dusty conditions with silicon compounds and especially silicon monoxide have signs of inflammatory processes on the mucous membranes.

see also

Write a review on the article "Silicon"

Comments

Notes

Literature

• Samsonov. G. V. Silicides and their use in engineering. - Kyiv, Publishing House of the Academy of Sciences of the Ukrainian SSR, 1959. - 204 p. from ill.

Links

Periodic system of chemical elements of D. I. Mendeleev
																												Si
																											Uut		Up		Uus	Uuo
	Uue	Ubn	Ubu	An excerpt characterizing Silicon - You will be good, deploying the front in front of the enemy, very good. “The enemy is still far away, Your Excellency. By disposition... - Disposition! - Kutuzov exclaimed bitterly, - and who told you this? ... If you please, do what you are ordered. - I listen with. - Mon cher, - Nesvitsky said in a whisper to Prince Andrei, - le vieux est d "une humeur de chien. [My dear, our old man is very out of sorts.] An Austrian officer with a green plume on his hat, in a white uniform, galloped up to Kutuzov and asked on behalf of the emperor: did the fourth column come forward? Kutuzov, without answering him, turned away, and his eyes accidentally fell on Prince Andrei, who was standing beside him. Seeing Bolkonsky, Kutuzov softened the angry and caustic expression of his gaze, as if realizing that his adjutant was not to blame for what was being done. And, without answering the Austrian adjutant, he turned to Bolkonsky: - Allez voir, mon cher, si la troisieme division a depasse le village. Dites lui de s "arreter et d" attendre mes ordres. [Go, my dear, see if the third division has passed through the village. Tell her to stop and wait for my order.] As soon as Prince Andrei drove off, he stopped him. “Et demandez lui, si les tirailleurs sont postes,” he added. - Ce qu "ils font, ce qu" ils font! [And ask if the arrows are placed. – What are they doing, what are they doing!] – he said to himself, still not answering the Austrian. Prince Andrei galloped off to fulfill the order. Having overtaken all the battalions walking in front, he stopped the 3rd division and made sure that, indeed, there was no firing line in front of our columns. The regimental commander of the regiment in front was very surprised by the order given to him by the commander in chief to scatter the shooters. The regimental commander stood there in full confidence that there were still troops ahead of him, and that the enemy could not be closer than 10 versts. Indeed, there was nothing to be seen ahead, except for the desert area, leaning forward and covered with thick fog. Ordering on behalf of the commander-in-chief to fulfill the omission, Prince Andrei galloped back. Kutuzov stood still in the same place and, senilely lowering himself in the saddle with his fat body, yawned heavily, closing his eyes. The troops were no longer moving, but their guns were at their feet. “Good, good,” he said to Prince Andrei and turned to the general, who, with a watch in his hands, said that it was time to move, since all the columns from the left flank had already descended. “We’ll still have time, Your Excellency,” Kutuzov said through a yawn. - We'll make it! he repeated. At this time, behind Kutuzov, the sounds of greeting regiments were heard in the distance, and these voices began to quickly approach along the entire length of the stretched line of advancing Russian columns. It was evident that the one with whom they greeted was driving quickly. When the soldiers of the regiment in front of which Kutuzov stood shouted, he drove a little to the side and looked around with a frown. On the road from Pracen, a squadron of multi-coloured riders galloped, as it were. Two of them galloped side by side ahead of the rest. One was in a black uniform with a white plume on a red english horse, the other in a white uniform on a black horse. These were two emperors with retinue. Kutuzov, with the affectation of a campaigner at the front, commanded the troops standing at attention and, saluting, rode up to the emperor. His whole figure and manner suddenly changed. He took on the appearance of a subordinate, unreasoning person. He, with an affectation of deference, which obviously struck the Emperor Alexander unpleasantly, rode up and saluted him. An unpleasant impression, only like the remnants of fog in a clear sky, ran across the young and happy face of the emperor and disappeared. He was, after ill health, somewhat thinner that day than on the Olmutz field, where Bolkonsky had seen him for the first time abroad; but the same charming combination of majesty and meekness was in his beautiful gray eyes, and on his thin lips the same possibility of various expressions and the prevailing expression of complacent, innocent youth. At the Olmyutsky review he was more majestic, here he was more cheerful and energetic. He flushed a little as he galloped those three versts, and, stopping his horse, sighed with relief and looked around at the faces of his retinue, just as young, just as animated as his own. Chartorizhsky and Novosiltsev, and Prince Bolkonsky, and Stroganov, and others, all richly dressed, cheerful, young people, on beautiful, well-groomed, fresh, just slightly sweaty horses, talking and smiling, stopped behind the sovereign. Emperor Franz, a ruddy, long-faced young man, sat extremely upright on a handsome black stallion and looked around him anxiously and unhurriedly. He called one of his white adjutants and asked something. "That's right, at what time they left," thought Prince Andrei, watching his old acquaintance, with a smile that he could not help remembering his audience. In the retinue of the emperors were selected fine fellow orderlies, Russian and Austrian, guards and army regiments. Between them, the beautiful spare royal horses were led by bereytors in embroidered blankets. It was as if through a dissolved window it suddenly smelled of fresh field air into a stuffy room, so the gloomy Kutuzov headquarters smelled of youth, energy and confidence in success from this brilliant youth that galloped up. - Why don't you start, Mikhail Larionovich? - Emperor Alexander hastily turned to Kutuzov, at the same time looking politely at Emperor Franz. “I am waiting, Your Majesty,” answered Kutuzov, leaning forward respectfully. The Emperor ducked his ear, frowning slightly to show that he hadn't heard. “I’m waiting, your Majesty,” Kutuzov repeated (Prince Andrey noticed that Kutuzov’s upper lip trembled unnaturally while he was waiting for this). “Not all the columns have gathered yet, Your Majesty. The sovereign heard, but this answer, apparently, did not please him; he shrugged his stooped shoulders, glanced at Novosiltsev, who was standing beside him, as if complaining about Kutuzov with this look. “After all, we are not in the Tsaritsyn Meadow, Mikhail Larionovich, where they don’t start the parade until all the regiments arrive,” said the sovereign, again looking into the eyes of Emperor Franz, as if inviting him, if not to take part, then listen to what he He speaks; but Emperor Franz, continuing to look around, did not listen. “That’s why I don’t start, sir,” said Kutuzov in a sonorous voice, as if warning the possibility of not being heard, and something trembled in his face again. “That’s why I don’t start, sir, because we are not at the parade and not on the Tsaritsy’s Meadow,” he said clearly and distinctly. In the retinue of the sovereign, all the faces, instantly exchanging glances with each other, expressed murmuring and reproach. "No matter how old he is, he shouldn't, he shouldn't speak like that," these faces expressed. The sovereign looked intently and attentively into Kutuzov's eyes, waiting for him to say something else. But Kutuzov, for his part, bowing his head respectfully, also seemed to be waiting. The silence lasted for about a minute. “However, if you order, your Majesty,” said Kutuzov, raising his head and again changing his tone to the former tone of a stupid, unreasoning, but obedient general. He touched the horse and, having called the head of the column Miloradovich to him, gave him the order to advance. The army stirred again, and two battalions of the Novgorod regiment and a battalion of the Apsheron regiment moved forward past the sovereign. While this Apsheron battalion, ruddy Miloradovich, without an overcoat, in a uniform and orders and with a hat with a huge sultan, put on sideways and from the field, was passing, the march galloped forward and, valiantly saluting, reined in the horse in front of the sovereign. “God bless you, general,” the emperor told him. - Ma foi, sire, nous ferons ce que qui sera dans notre possibilite, sire, [Really, your majesty, we will do what it will be possible for us to do, your majesty,] - he answered cheerfully, nevertheless causing a mocking smile from the gentlemen retinue of the sovereign with his bad French accent. Miloradovich abruptly turned his horse and stood somewhat behind the sovereign. The Absheronians, excited by the presence of the sovereign, valiantly, briskly beating off their feet, passed by the emperors and their retinues. - Guys! - Miloradovich shouted in a loud, self-confident and cheerful voice, apparently excited to such an extent by the sounds of shooting, the expectation of battle and the sight of the fine fellows of the Apsheron, still their Suvorov comrades, briskly passing by the emperors, that he forgot about the presence of the sovereign. - Guys, you do not take the first village! he shouted. - Glad to try! the soldiers shouted. The sovereign's horse shied away from an unexpected cry. This horse, which had carried the sovereign at reviews in Russia, here, on the Field of Austerlitz, carried its rider, withstanding his scattered blows with his left foot, alerted his ears to the sounds of shots, just as she did it on the Field of Mars, not understanding the meaning of any these heard shots, nor the neighborhood of the black stallion of Emperor Franz, nor everything that the one who rode it said, thought, felt that day. The sovereign turned to one of his entourage with a smile, pointing to the fellow Absherons, and said something to him. Kutuzov, accompanied by his adjutants, rode at a pace behind the carabinieri. Having traveled half a verst at the tail of the column, he stopped at a lonely abandoned house (probably a former tavern) near the fork of two roads. Both roads descended downhill, and troops marched along both. The fog began to disperse, and indefinitely, at a distance of two versts, enemy troops could already be seen on opposite hills. To the left below the shooting became more audible. Kutuzov stopped talking to the Austrian general. Prince Andrei, standing somewhat behind, peered at them and, wanting to ask the adjutant for a telescope, turned to him. “Look, look,” this adjutant said, looking not at the distant army, but down the mountain in front of him. - They're French! Two generals and adjutants began to grab the pipe, pulling it out one from the other. All the faces suddenly changed, and horror was expressed on everyone. The French were supposed to be two miles away from us, but they appeared suddenly, unexpectedly in front of us. - Is this an enemy? ... No! ... Yes, look, he ... probably ... What is this? voices were heard. Prince Andrey with a simple eye saw a dense column of French rising to the right towards the Apsheronians, no further than five hundred paces from the place where Kutuzov was standing. “Here it is, the decisive moment has come! It came to me, ”thought Prince Andrei, and hitting his horse, drove up to Kutuzov. “We must stop the Apsheronians,” he shouted, “your excellency!” But at the same moment, everything was covered in smoke, close-range shooting was heard, and a naively frightened voice, two steps away from Prince Andrei, shouted: “Well, brothers, the Sabbath!” And as if this voice was a command. At this voice, everything rushed to run. Mixed, ever-increasing crowds fled back to the place where five minutes ago the troops passed by the emperors. It was not only difficult to stop this crowd, but it was impossible not to move back together with the crowd. Bolkonsky only tried to keep up with her and looked around, perplexed and unable to understand what was happening in front of him. Nesvitsky, with an angry look, red and not like himself, shouted to Kutuzov that if he did not leave now, he would probably be taken prisoner. Kutuzov stood in the same place and, without answering, took out his handkerchief. Blood was flowing from his cheek. Prince Andrei pushed his way up to him. - Are you injured? he asked, barely able to control the trembling of his lower jaw. - The wounds are not here, but where! - said Kutuzov, pressing a handkerchief to his wounded cheek and pointing to the fugitives. - Stop them! he shouted, and at the same time, probably convinced that it was impossible to stop them, he hit his horse and rode to the right. The crowd of fugitives, again surging, took him with them and dragged him back. The troops fled in such a dense crowd that, once they got into the middle of the crowd, it was difficult to get out of it. Who shouted: “Go! what's the delay?" Who immediately, turning around, fired into the air; who beat the horse on which Kutuzov himself rode. With the greatest effort, getting out of the stream of the crowd to the left, Kutuzov with a retinue, reduced by more than half, went to the sounds of nearby gun shots. Getting out of the crowd of fleeing, Prince Andrei, trying to keep up with Kutuzov, saw on the slope of the mountain, in the smoke, a Russian battery still firing and the French running up to it. The Russian infantry stood higher, moving neither forward to help the battery, nor backward in the same direction as the fugitives. The general on horseback separated from this infantry and rode up to Kutuzov. Only four people remained from Kutuzov's retinue. Everyone was pale and looked at each other silently. - Stop those bastards! - panting, said Kutuzov to the regimental commander, pointing to the fugitives; but at the same moment, as if in punishment for these words, like a swarm of birds, bullets whistled over the regiment and Kutuzov's retinue. The French attacked the battery and, seeing Kutuzov, fired at him. With this volley, the regimental commander grabbed his leg; several soldiers fell, and the ensign, who was standing with the banner, let go of it; the banner staggered and fell, lingering on the guns of neighboring soldiers. Soldiers without a command began to shoot. - Oooh! Kutuzov mumbled with an expression of despair and looked around. “Bolkonsky,” he whispered in a voice trembling from the consciousness of his senile impotence. “Bolkonsky,” he whispered, pointing to the disorganized battalion and the enemy, “what is this? But before he finished these words, Prince Andrei, feeling tears of shame and anger rising to his throat, was already jumping off his horse and running to the banner. - Guys, go ahead! he shouted childishly. "Here it is!" thought Prince Andrei, grabbing the staff of the banner and listening with pleasure to the whistle of bullets, obviously directed precisely against him. Several soldiers fell. - Hooray! - shouted Prince Andrei, barely holding the heavy banner in his hands, and ran forward with undoubted confidence that the whole battalion would run after him. Indeed, he ran only a few paces alone. One, another soldier set off, and the whole battalion shouted "Hurrah!" ran ahead and overtook him. The non-commissioned officer of the battalion, running up, took the banner that wavered from the weight in the hands of Prince Andrei, but was immediately killed. Prince Andrei again grabbed the banner and, dragging it by the shaft, fled with the battalion. In front of him, he saw our gunners, some of whom were fighting, others were throwing their cannons and running towards him; he also saw French infantry soldiers seizing artillery horses and turning the cannons. Prince Andrei with the battalion was already 20 paces from the guns. He heard the unceasing whistle of bullets above him, and the soldiers to the right and left of him ceaselessly groaned and fell. But he did not look at them; he peered only at what was happening in front of him - on the battery. He clearly saw already one figure of a red-haired artilleryman with a shako knocked to one side, pulling a bannik from one side, while a French soldier was pulling a bannik towards him from the other side. Prince Andrei already saw the clearly bewildered and at the same time embittered expression on the faces of these two people, who apparently did not understand what they were doing. "What are they doing? - thought Prince Andrei, looking at them: - why does not the red-haired artilleryman run when he has no weapons? Why doesn't the Frenchman prick him? Before he has time to run, the Frenchman will remember the gun and stab him.” Indeed, another Frenchman, with a gun overweight, ran up to the fighters, and the fate of the red-haired artilleryman, who still did not understand what awaited him, and triumphantly pulled out a banner, was to be decided. But Prince Andrei did not see how it ended. As if from the full swing of a strong stick, one of the nearest soldiers, as it seemed to him, hit him in the head. It hurt a little, and most importantly, unpleasant, because this pain entertained him and prevented him from seeing what he was looking at. "What is it? I'm falling? my legs give way, ”he thought, and fell on his back. He opened his eyes, hoping to see how the fight between the French and the artillerymen ended, and wishing to know whether the red-haired artilleryman had been killed or not, whether the guns had been taken or saved. But he didn't take anything. Above him there was nothing but the sky—a high sky, not clear, but still immeasurably high, with gray clouds quietly creeping across it. “How quiet, calm and solemn, not at all the way I ran,” thought Prince Andrei, “not the way we ran, shouted and fought; not in the same way as the Frenchman and the artilleryman dragged each other's bannik with angry and frightened faces - not at all like the clouds crawling across this high, endless sky. How could I not have seen this lofty sky before? And how happy I am that I finally got to know him. Yes! everything is empty, everything is a lie, except for this endless sky. Nothing, nothing but him. But even that is not even there, there is nothing but silence, calmness. And thank God!…" On the right flank at Bagration at 9 o'clock, the matter had not yet begun. Not wanting to agree to Dolgorukov's demand to start a business and wanting to deflect responsibility from himself, Prince Bagration suggested that Dolgorukov send the commander in chief to ask about it. Bagration knew that, at a distance of almost 10 miles, separating one flank from the other, if they did not kill the one who was sent (which was very likely), and if he even found the commander in chief, which was very difficult, the sent one would not have time to return earlier evenings. Bagration glanced at his retinue with his large, expressionless, sleepy eyes, and Rostov's childish face, involuntarily dying with excitement and hope, was the first to catch his eye. He sent it. - And if I meet his majesty before the commander-in-chief, your excellency? - said Rostov, holding his hand to the visor. “You can pass it on to His Majesty,” said Dolgorukov hastily interrupting Bagration. Having changed from the chain, Rostov managed to sleep a few hours before morning and felt cheerful, bold, resolute, with that elasticity of movements, confidence in his happiness and in that mood in which everything seems easy, fun and possible. All his desires were fulfilled this morning; a general battle was given, he participated in it; moreover, he was an orderly under the bravest general; moreover, he went on an assignment to Kutuzov, and perhaps to the sovereign himself. The morning was clear, the horse under it was kind. His heart was full of joy and happiness. Having received the order, he started his horse and galloped along the line. At first he rode along the line of Bagration's troops, who had not yet entered into action and stood motionless; then he drove into the space occupied by Uvarov's cavalry and here he already noticed movements and signs of preparations for the case; having passed Uvarov's cavalry, he already clearly heard the sounds of cannon and cannon fire in front of him. The shooting intensified.

Silicon

SILICON-I; m.[from Greek. krēmnos - cliff, rock] A chemical element (Si), dark gray crystals with a metallic sheen, which are part of most rocks.

◁ Silicon, th, th. K salts. Siliceous (see 2.K .; 1 sign).

silicon

(lat. Silicium), a chemical element of group IV of the periodic system. Dark gray crystals with a metallic sheen; density 2.33 g / cm 3, t pl 1415ºC. Resistant to chemical attack. It makes up 27.6% of the mass of the earth's crust (2nd place among the elements), the main minerals are silica and silicates. One of the most important semiconductor materials (transistors, thermistors, photocells). An integral part of many steels and other alloys (increases mechanical strength and corrosion resistance, improves casting properties).

SILICON

SILICON (lat. Silicium from silex - flint), Si (read "silicium", but now quite often as "si"), a chemical element with atomic number 14, atomic mass 28.0855. The Russian name comes from the Greek kremnos - cliff, mountain.
Natural silicon consists of a mixture of three stable nuclides (cm. NUCLIDE) with mass numbers 28 (prevails in the mixture, it is 92.27% by mass in it), 29 (4.68%) and 30 (3.05%). Configuration of the outer electron layer of a neutral unexcited silicon atom 3 s 2 R 2 . In compounds, it usually exhibits an oxidation state of +4 (valency IV) and very rarely +3, +2 and +1 (valencies III, II and I, respectively). In the periodic system of Mendeleev, silicon is located in the IVA group (in the carbon group), in the third period.
The radius of the neutral silicon atom is 0.133 nm. Sequential ionization energies of silicon atom are 8.1517, 16.342, 33.46 and 45.13 eV, electron affinity is 1.22 eV. The radius of the Si 4+ ion with a coordination number of 4 (the most common in the case of silicon) is 0.040 nm, with a coordination number of 6 - 0.054 nm. On the Pauling scale, the electronegativity of silicon is 1.9. Although silicon is usually classified as a non-metal, it occupies an intermediate position between metals and non-metals in a number of properties.
In free form - brown powder or light gray compact material with a metallic sheen.
Discovery history
Silicon compounds have been known to man since time immemorial. But with a simple substance silicon man met only about 200 years ago. In fact, the first researchers who received silicon were the French J. L. Gay-Lussac (cm. GAY LUSSAC Joseph Louis) and L. J. Tenard (cm. TENAR Louis Jacques). They discovered in 1811 that heating silicon fluoride with metallic potassium leads to the formation of a brownish-brown substance:
SiF 4 + 4K = Si + 4KF, however, the researchers themselves did not make the correct conclusion about obtaining a new simple substance. The honor of discovering a new element belongs to the Swedish chemist J. Berzelius (cm. BERZELIUS Jens Jacob), who also heated a compound of the composition K 2 SiF 6 with metallic potassium to obtain silicon. He received the same amorphous powder as the French chemists, and in 1824 announced a new elemental substance, which he called "silicon". Crystalline silicon was obtained only in 1854 by the French chemist A. E. St. Clair Deville (cm. SAINT CLAIR DEVILLE Henri Etienne) .
Being in nature
In terms of prevalence in the earth's crust, silicon ranks second among all elements (after oxygen). Silicon accounts for 27.7% of the mass of the earth's crust. Silicon is part of several hundred different natural silicates (cm. SILICATES) and aluminosilicates (cm. ALUMOSILICATES). Silica, or silicon dioxide, is also widely distributed (cm. SILICON DIOXIDE) SiO 2 (river sand (cm. SAND), quartz (cm. QUARTZ), flint (cm. FLINT) and others), which makes up about 12% of the earth's crust (by mass). Silicon is not found in free form in nature.
Receipt
In industry, silicon is obtained by reducing the SiO 2 melt with coke at a temperature of about 1800°C in arc furnaces. The purity of the silicon thus obtained is about 99.9%. Since silicon of a higher purity is needed for practical use, the resulting silicon is chlorinated. Compounds of the composition SiCl 4 and SiCl 3 H are formed. These chlorides are further purified by various methods from impurities and, at the final stage, are reduced with pure hydrogen. It is also possible to purify silicon by preliminary obtaining magnesium silicide Mg 2 Si. Further, volatile monosilane SiH 4 is obtained from magnesium silicide using hydrochloric or acetic acid. Monosilane is further purified by distillation, sorption, and other methods, and then decomposed into silicon and hydrogen at a temperature of about 1000°C. The content of impurities in the silicon obtained by these methods is reduced to 10 -8 -10 -6% by weight.
Physical and chemical properties
The crystal lattice of silicon is a cubic face-centered type of diamond, parameter a = 0.54307 nm (other polymorphic modifications of silicon were also obtained at high pressures), but due to the longer bond length between Si-Si atoms compared to the C-C bond length, the hardness of silicon is much less than that of diamond.
The density of silicon is 2.33 kg/dm 3 . Melting point 1410°C, boiling point 2355°C. Silicon is brittle, only when heated above 800°C does it become plastic. Interestingly, silicon is transparent to infrared (IR) radiation.
Elemental silicon is a typical semiconductor (cm. SEMICONDUCTORS). The band gap at room temperature is 1.09 eV. The concentration of current carriers in silicon with intrinsic conductivity at room temperature is 1.5·10 16 m -3 . The electrical properties of crystalline silicon are greatly affected by the microimpurities contained in it. To obtain single crystals of silicon with hole conductivity, additives of elements of the III group - boron are introduced into silicon (cm. BOR (chemical element)), aluminum (cm. ALUMINUM), gallium (cm. GALLIUM) and india (cm. INDIUM), with electronic conductivity - additives of elements of the V-th group - phosphorus (cm. PHOSPHORUS), arsenic (cm. ARSENIC) or antimony (cm. ANTIMONY). The electrical properties of silicon can be varied by changing the conditions for processing single crystals, in particular, by treating the silicon surface with various chemical agents.
Chemically, silicon is inactive. At room temperature, it reacts only with gaseous fluorine to form volatile silicon tetrafluoride SiF 4 . When heated to a temperature of 400-500°C, silicon reacts with oxygen to form dioxide SiO 2 , with chlorine, bromine and iodine - to form the corresponding easily volatile tetrahalides SiHal 4 .
Silicon does not directly react with hydrogen, silicon compounds with hydrogen are silanes (cm. SILANES) with the general formula Si n H 2n+2 - obtained indirectly. Monosilane SiH 4 (it is often called simply silane) is released during the interaction of metal silicides with acid solutions, for example:
Ca 2 Si + 4HCl \u003d 2CaCl 2 + SiH 4
The silane SiH 4 formed in this reaction contains an admixture of other silanes, in particular, disilane Si 2 H 6 and trisilane Si 3 H 8, in which there is a chain of silicon atoms interconnected by single bonds (-Si-Si-Si-) .
With nitrogen, silicon at a temperature of about 1000°C forms nitride Si 3 N 4 , with boron - thermally and chemically stable borides SiB 3 , SiB 6 and SiB 12 . The compound of silicon and its closest analogue according to the periodic table - carbon - silicon carbide SiC (carborundum (cm. CARBORUNDUM)) is characterized by high hardness and low chemical activity. Carborundum is widely used as an abrasive material.
When silicon is heated with metals, silicides are formed (cm. SILICIDES). Silicides can be divided into two groups: ionic-covalent (silicides of alkali, alkaline earth metals and magnesium such as Ca 2 Si, Mg 2 Si, etc.) and metal-like (transition metal silicides). Silicides of active metals decompose under the action of acids, silicides of transition metals are chemically stable and do not decompose under the action of acids. Metal-like silicides have high melting points (up to 2000°C). Metal-like silicides of compositions MSi, M 3 Si 2 , M 2 Si 3 , M 5 Si 3 , and MSi 2 are formed most frequently. Metal-like silicides are chemically inert, resistant to oxygen even at high temperatures.
Silicon dioxide SiO 2 is an acidic oxide that does not react with water. Exists in the form of several polymorphic modifications (quartz (cm. QUARTZ), tridymite, cristobalite, glassy SiO 2). Of these modifications, quartz has the greatest practical value. Quartz has piezoelectric properties (cm. PIEZOELECTRIC MATERIALS), it is transparent to ultraviolet (UV) radiation. It is characterized by a very low coefficient of thermal expansion, so the dishes made of quartz do not crack at temperature drops of up to 1000 degrees.
Quartz is chemically resistant to acids, but reacts with hydrofluoric acid:
SiO 2 + 6HF \u003d H 2 + 2H 2 O
and gaseous hydrogen fluoride HF:
SiO 2 + 4HF \u003d SiF 4 + 2H 2 O
These two reactions are widely used for glass etching.
When SiO 2 is fused with alkalis and basic oxides, as well as with carbonates of active metals, silicates are formed (cm. SILICATES)- salts of very weak, water-insoluble silicic acids that do not have a constant composition (cm. SILICON ACIDS) the general formula xH 2 O ySiO 2 (quite often in the literature they do not write very accurately not about silicic acids, but about silicic acid, although in fact we are talking about the same thing). For example, sodium orthosilicate can be obtained:
SiO 2 + 4NaOH \u003d (2Na 2 O) SiO 2 + 2H 2 O,
calcium metasilicate:
SiO 2 + CaO \u003d CaO SiO 2
or mixed calcium and sodium silicate:
Na 2 CO 3 + CaCO 3 + 6SiO 2 = Na 2 O CaO 6SiO 2 + 2CO 2
Window glass is made from Na 2 O CaO 6SiO 2 silicate.
It should be noted that most silicates do not have a constant composition. Of all the silicates, only sodium and potassium silicates are soluble in water. Solutions of these silicates in water are called soluble glass. Due to hydrolysis, these solutions are characterized by a strongly alkaline environment. Hydrolyzed silicates are characterized by the formation of not true, but colloidal solutions. When acidifying solutions of sodium or potassium silicates, a gelatinous white precipitate of hydrated silicic acids precipitates.
The main structural element of both solid silicon dioxide and all silicates is the group in which the silicon atom Si is surrounded by a tetrahedron of four oxygen atoms O. In this case, each oxygen atom is connected to two silicon atoms. Fragments can be linked to each other in different ways. Among the silicates, according to the nature of the bonds in them, the fragments are divided into island, chain, ribbon, layered, framework, and others.
When SiO 2 is reduced with silicon at high temperatures, silicon monoxide of the composition SiO is formed.
Silicon is characterized by the formation of organosilicon compounds (cm. SILICON COMPOUNDS), in which silicon atoms are connected in long chains due to bridging oxygen atoms -O-, and to each silicon atom, except for two O atoms, two more organic radicals R 1 and R 2 \u003d CH 3, C 2 H 5, C 6 are attached H 5 , CH 2 CH 2 CF 3 and others.
Application
Silicon is used as a semiconductor material. Quartz is used as a piezoelectric material, as a material for the manufacture of heat-resistant chemical (quartz) dishes, and UV radiation lamps. Silicates are widely used as building materials. Window panes are amorphous silicates. Silicone materials are characterized by high wear resistance and are widely used in practice as silicone oils, adhesives, rubbers, and varnishes.
Biological role
For some organisms, silicon is an important biogenic element. (cm. BIOGENIC ELEMENTS). It is part of the supporting structures in plants and skeletal structures in animals. In large quantities, silicon is concentrated by marine organisms - diatoms. (cm. DIATOM ALGAE), radiolarians (cm. RADIOLARIA), sponges (cm. SPONGE). Human muscle tissue contains (1-2) 10 -2% silicon, bone tissue - 17 10 -4%, blood - 3.9 mg / l. With food, up to 1 g of silicon enters the human body daily.
Silicon compounds are not poisonous. But it is very dangerous to inhale highly dispersed particles of both silicates and silicon dioxide, which are formed, for example, during blasting, when chiselling rocks in mines, during the operation of sandblasting machines, etc. SiO 2 microparticles that enter the lungs crystallize in them, and the resulting crystals destroy the lung tissue and cause a serious illness - silicosis (cm. SILICOSIS). To prevent this dangerous dust from entering the lungs, a respirator should be used for respiratory protection.

encyclopedic Dictionary. 2009 .

Synonyms:

See what "silicon" is in other dictionaries:

- (symbol Si), a widespread gray chemical element of group IV of the periodic table, non-metal. It was first isolated by Jens BERZELIUS in 1824. Silicon is found only in compounds such as SILICA (silicon dioxide) or in ... ... Scientific and technical encyclopedic dictionary

Silicon- is obtained almost exclusively by carbothermal reduction of silicon dioxide using electric arc furnaces. It is a poor conductor of heat and electricity, harder than glass, usually in the form of a powder or more often shapeless pieces ... ... Official terminology

SILICON- chem. element, non-metal, symbol Si (lat. Silicium), at. n. 14, at. m. 28.08; amorphous and crystalline silicon (which is built from crystals of the same type as diamond) are known. Amorphous K. brown powder of a cubic structure in a highly dispersed ... ... Great Polytechnic Encyclopedia

- (Silicium), Si, a chemical element of group IV of the periodic system, atomic number 14, atomic mass 28.0855; non-metal, mp 1415shC. Silicon is the second most abundant element on Earth after oxygen, the content in the earth's crust is 27.6% by mass. ... ... Modern Encyclopedia

Si (lat. Silicium * a. silicium, silicon; n. Silizium; f. silicium; and. siliseo), chem. element IV group periodic. Mendeleev systems, at. n. 14, at. m. 28.086. In nature, there are 3 stable isotopes 28Si (92.27), 29Si (4.68%), 30Si (3 ... Geological Encyclopedia

Silicon compounds, widely distributed on earth, have been known to man since the Stone Age. The use of stone tools for labor and hunting continued for several millennia. The use of silicon compounds associated with their processing - the manufacture of glass - began around 3000 BC. e. (in ancient Egypt). The earliest known Silicon compound is SiO 2 oxide (silica). In the 18th century, silica was considered a simple body and referred to "earths" (which is reflected in its name). The complexity of the composition of silica was established by I. Ya. Berzelius. He was the first, in 1825, to obtain elemental silicon from silicon fluoride SiF 4 , reducing the latter with metallic potassium. The new element was given the name "silicon" (from the Latin silex - flint). The Russian name was introduced by G.I. Hess in 1834.

Distribution of Silicon in nature. In terms of prevalence in the earth's crust, silicon is the second (after oxygen) element, its average content in the lithosphere is 29.5% (by mass). In the earth's crust, silicon plays the same primary role as carbon in the animal and plant kingdoms. For the geochemistry of silicon, its exceptionally strong bond with oxygen is important. About 12% of the lithosphere is silica SiO 2 in the form of the mineral quartz and its varieties. 75% of the lithosphere is composed of various silicates and aluminosilicates (feldspars, micas, amphiboles, etc.). The total number of minerals containing silica exceeds 400.

Silicon is weakly differentiated during magmatic processes: it accumulates both in granitoids (32.3%) and in ultramafic rocks (19%). At high temperatures and high pressures, the solubility of SiO 2 increases. It can also migrate with water vapor; therefore, pegmatites of hydrothermal veins are characterized by significant concentrations of quartz, which is often associated with ore elements (gold-quartz, quartz-cassiterite, and other veins).

Physical properties of Silicon. Silicon forms dark gray crystals with a metallic sheen, having a cubic face-centered diamond-type lattice with a period a = 5.431Å, density 2.33 g/cm 3 . At very high pressures, a new (probably hexagonal) modification with a density of 2.55 g/cm 3 was obtained. Silicon melts at 1417°C and boils at 2600°C. Specific heat capacity (at 20-100 °C) 800 J/(kg K), or 0.191 cal/(g deg); thermal conductivity, even for the purest samples, is not constant and is in the range (25 ° C) 84-126 W / (m K), or 0.20-0.30 cal / (cm s deg). The temperature coefficient of linear expansion 2,33·10 -6 K -1 below 120 K becomes negative. Silicon is transparent to long-wave infrared rays; refractive index (for λ = 6 μm) 3.42; dielectric constant 11.7. Silicon is diamagnetic, atomic magnetic susceptibility -0.13-10 -6. Silicon hardness according to Mohs 7.0, according to Brinell 2.4 Gn / m 2 (240 kgf / mm 2), modulus of elasticity 109 Gn / m 2 (10 890 kgf / mm 2), compressibility coefficient 0.325 10 -6 cm 2 /kg. Silicon is a brittle material; noticeable plastic deformation begins at temperatures above 800°C.

Silicon is a semiconductor with a wide range of applications. The electrical properties of Silicon are highly dependent on impurities. The intrinsic specific volume electrical resistance of Silicon at room temperature is assumed to be 2.3·10 3 ohm·m (2.3·10 5 ohm·cm).

Semiconductor Silicon with p-type conductivity (additives B, Al, In or Ga) and n-type (additives P, Bi, As or Sb) has a much lower resistance. The band gap according to electrical measurements is 1.21 eV at 0 K and decreases to 1.119 eV at 300 K.

Chemical properties of Silicon. In accordance with the position of Silicon in the periodic system of Mendeleev, 14 electrons of the Silicon atom are distributed over three shells: in the first (from the nucleus) 2 electrons, in the second 8, in the third (valence) 4; electron shell configuration 1s 2 2s 2 2p 6 3s 2 3p 2 . Sequential ionization potentials (eV): 8.149; 16.34; 33.46 and 45.13. Atomic radius 1.33Å, covalent radius 1.17Å, ionic radii Si 4+ 0.39Å, Si 4- 1.98Å.

In compounds Silicon (similar to carbon) is 4-valent. However, unlike carbon, Silicon, along with a coordination number of 4, exhibits a coordination number of 6, which is explained by the large volume of its atom (an example of such compounds are silicon fluorides containing a 2- group).

The chemical bonding of the Silicon atom with other atoms is usually carried out through hybrid sp 3 orbitals, but it is also possible to involve two of its five (vacant) 3d orbitals, especially when Silicon is six-coordinated. Possessing a low electronegativity value of 1.8 (against 2.5 for carbon; 3.0 for nitrogen, etc.), silicon in compounds with non-metals is electropositive, and these compounds are polar in nature. The high bonding energy with oxygen Si - O, equal to 464 kJ / mol (111 kcal / mol), determines the stability of its oxygen compounds (SiO 2 and silicates). The Si-Si bond energy is low, 176 kJ/mol (42 kcal/mol); unlike carbon, silicon is not characterized by the formation of long chains and a double bond between Si atoms. Due to the formation of a protective oxide film, silicon is stable even at elevated temperatures in air. In oxygen, it oxidizes starting from 400 ° C, forming silicon oxide (IV) SiO 2. Silicon oxide (II) SiO is also known, which is stable at high temperatures in the form of a gas; as a result of rapid cooling, a solid product can be obtained, which easily decomposes into a thin mixture of Si and SiO 2 . Silicon is resistant to acids and dissolves only in a mixture of nitric and hydrofluoric acids; easily dissolves in hot alkali solutions with evolution of hydrogen. Silicon reacts with fluorine at room temperature, with other halogens - when heated to form compounds of the general formula SiX 4 . Hydrogen does not directly react with Silicon, and silicon hydrides (silanes) are obtained by decomposition of silicides (see below). Silicon hydrogens are known from SiH 4 to Si 8 H 18 (similar in composition to saturated hydrocarbons). Silicon forms 2 groups of oxygen-containing silanes - siloxanes and siloxenes. Silicon reacts with nitrogen at temperatures above 1000 ° C. Si 3 N 4 nitride is of great practical importance, it does not oxidize in air even at 1200 ° C, it is resistant to acids (except nitric) and alkalis, as well as to molten metals and slags , which makes it a valuable material for the chemical industry, for the production of refractories and others. Silicon compounds with carbon (silicon carbide SiC) and boron (SiB 3 , SiB 6 , SiB 12) are characterized by high hardness, as well as thermal and chemical resistance. When heated, silicon reacts (in the presence of metal catalysts, such as copper) with organochlorine compounds (for example, with CH 3 Cl) to form organohalosilanes [for example, Si(CH 3) 3 Cl], which are used for the synthesis of numerous organosilicon compounds.

Silicon forms compounds with almost all metals - silicides (compounds were not found only with Bi, Tl, Pb, Hg). More than 250 silicides have been obtained, the composition of which (MeSi, MeSi 2 , Me 5 Si 3 , Me 3 Si, Me 2 Si and others) usually does not correspond to classical valencies. Silicides are distinguished by their refractoriness and hardness; of greatest practical importance are ferrosilicon (a reducing agent in the smelting of special alloys, see Ferroalloys) and molybdenum silicide MoSi 2 (electric furnace heaters, gas turbine blades, etc.).

Getting Silicon. Silicon of technical purity (95-98%) is obtained in an electric arc by the reduction of silica SiO 2 between graphite electrodes. In connection with the development of semiconductor technology, methods have been developed for obtaining pure and especially pure Silicon. This requires a preliminary synthesis of the purest initial Silicon compounds, from which Silicon is extracted by reduction or thermal decomposition.

Pure semiconductor Silicon is obtained in two forms: polycrystalline (by reduction of SiCl 4 or SiHCl 3 with zinc or hydrogen, thermal decomposition of SiI 4 and SiH 4) and single-crystal (by crucibleless zone melting and "pulling" a single crystal from molten silicon - the Czochralski method).

The use of silicon. Specially doped silicon is widely used as a material for the manufacture of semiconductor devices (transistors, thermistors, power rectifiers, thyristors; solar photocells used in spacecraft, etc.). Since silicon is transparent to rays with a wavelength of 1 to 9 microns, it is used in infrared optics,

Silicon has diverse and ever-expanding applications. In metallurgy, silicon is used to remove oxygen dissolved in molten metals (deoxidation). Silicon is an integral part of a large number of iron and non-ferrous alloys. Silicon usually gives alloys increased resistance to corrosion, improves their casting properties and increases mechanical strength; however, at higher levels, silicon can cause brittleness. The most important are iron, copper and aluminum alloys containing Silicon. An increasing amount of silicon is used for the synthesis of organosilicon compounds and silicides. Silica and many silicates (clays, feldspars, micas, talcs, etc.) are processed by glass, cement, ceramics, electrical engineering and other industries.

Silicon is found in the body in the form of various compounds involved mainly in the formation of solid skeletal parts and tissues. Some marine plants (for example, diatoms) and animals (for example, silicon-horned sponges, radiolarians) can accumulate especially much Silicon, forming thick deposits of silicon oxide (IV) on the ocean floor when they die. In cold seas and lakes, biogenic silts enriched with Silicon predominate in the tropical. seas - calcareous silts with a low content of Silicon. Among terrestrial plants, grasses, sedges, palms, and horsetails accumulate a lot of Silicon. In vertebrates, the content of silicon oxide (IV) in ash substances is 0.1-0.5%. Silicon is found in the largest quantities in dense connective tissue, kidneys, and pancreas. The daily human diet contains up to 1 g of Silicon. With a high content of silicon oxide (IV) dust in the air, it enters the lungs of a person and causes a disease - silicosis.

Silicon in the body. Silicon is found in the body in the form of various compounds involved mainly in the formation of solid skeletal parts and tissues. Some marine plants (for example, diatoms) and animals (for example, silicon-horned sponges, radiolarians) can accumulate especially much Silicon, forming thick deposits of silicon oxide (IV) on the ocean floor when they die. In cold seas and lakes, biogenic silts enriched with Silicon predominate in the tropical. seas - calcareous silts with a low content of Silicon. Among terrestrial plants, grasses, sedges, palms, and horsetails accumulate a lot of Silicon. In vertebrates, the content of silicon oxide (IV) in ash substances is 0.1-0.5%. Silicon is found in the largest quantities in dense connective tissue, kidneys, and pancreas. The daily human diet contains up to 1 g of Silicon. With a high content of silicon oxide (IV) dust in the air, it enters the lungs of a person and causes a disease - silicosis.

Silicon in free form was isolated in 1811 by J. Gay-Lussac and L. Tenard by passing vapors of silicon fluoride over metallic potassium, but it was not described by them as an element. The Swedish chemist J. Berzelius in 1823 gave a description of the silicon obtained by him by treating the potassium salt K 2 SiF 6 with potassium metal at high temperature. The new element was given the name "silicon" (from the Latin silex - flint). The Russian name "silicon" was introduced in 1834 by the Russian chemist German Ivanovich Hess. Translated from other Greek. krhmnoz- "cliff, mountain".

Being in nature, getting:

In nature, silicon is found in the form of dioxide and silicates of various compositions. Natural silicon dioxide occurs mainly in the form of quartz, although other minerals exist - cristobalite, tridymite, kitite, cousite. Amorphous silica is found in diatom deposits at the bottom of the seas and oceans - these deposits were formed from SiO 2, which was part of diatoms and some ciliates.
Free silicon can be obtained by calcining fine white sand with magnesium, which is almost pure silicon oxide in chemical composition, SiO 2 +2Mg=2MgO+Si. Industrial grade silicon is obtained by reducing the SiO 2 melt with coke at a temperature of about 1800°C in arc furnaces. The purity of silicon obtained in this way can reach 99.9% (the main impurities are carbon, metals).

Physical properties:

Amorphous silicon has the form of a brown powder, the density of which is 2.0 g/cm 3 . Crystalline silicon - a dark gray, shiny crystalline substance, brittle and very hard, crystallizes in the diamond lattice. It is a typical semiconductor (conducts electricity better than a rubber-type insulator, and worse than a conductor - copper). Silicon is brittle, only when heated above 800 °C does it become plastic. Interestingly, silicon is transparent to infrared radiation starting at a wavelength of 1.1 micrometers.

Chemical properties:

Chemically, silicon is inactive. At room temperature, it reacts only with gaseous fluorine to form volatile silicon tetrafluoride SiF 4 . When heated to a temperature of 400-500 ° C, silicon reacts with oxygen to form dioxide, with chlorine, bromine and iodine - to form the corresponding easily volatile tetrahalides SiHal 4 . At a temperature of about 1000°C, silicon reacts with nitrogen to form nitride Si 3 N 4 , with boron - thermally and chemically stable borides SiB 3 , SiB 6 and SiB 12 . Silicon does not directly react with hydrogen.
For silicon etching, a mixture of hydrofluoric and nitric acids is most widely used.
Silicon dissolves in hot alkali solutions: Si + 2KOH + H 2 O = K 2 SiO 3 + 2H 2
Silicon is characterized by compounds with an oxidation state of +4 or -4.

The most important connections:

Silicon dioxide, SiO 2- (silicic anhydride), colorless. crist. substance, refractory (1720 C), with high hardness. Acid oxide, chemically inactive, interacts with hydrofluoric acid and alkali solutions, forming in the latter case salts of silicic acids - silicates. Silicates are also formed when silicon oxide is fused with alkalis, basic oxides, and some salts.
SiO 2 + 4NaOH = Na 4 SiO 4 + 2H 2 O; SiO 2 + CaO \u003d CaSiO 3;
Na 2 CO 3 + CaCO 3 + 6SiO 2 = Na 2 CaSi 6 O 14 + 2CO 2 (mixed sodium calcium silicate, glass)
Silicic acids- weak, insoluble, formed by adding acid to a silicate solution in the form of a gel (gelatinous substance). H 4 SiO 4 (orthosilicon) and H 2 SiO 3 (metasilicon, or silicon) exist only in solution and irreversibly turn into SiO 2 when heated and dried. The resulting solid porous product - silica gel, has a developed surface and is used as a gas adsorbent, desiccant, catalyst and catalyst carrier.
silicates- salts of silicic acids for the most part (except for sodium and potassium silicates) are insoluble in water. Soluble silicates in solution undergo strong hydrolysis.
Hydrogen compounds- analogues of hydrocarbons, silanes, compounds in which silicon atoms are connected by a single bond, Silenes if the silicon atoms are double bonded. Like hydrocarbons, these compounds form chains and rings. All silanes can ignite spontaneously, form explosive mixtures with air and easily react with water: SiH 4 + 2H 2 O \u003d SiO 2 + 4H 2
Silicon tetrafluoride SiF 4, a gas with an unpleasant odor, poisonous, formed by the action of hydrofluoric (hydrofluoric) acid on silicon and many of its compounds, including glass:
Na 2 SiO 3 + 6HF = 2NaF + SiF 4 + 3H 2 O
Reacts with water to form silica and hexafluorosilicon(H 2 SiF 6) acids:
3SiF 4 + 3H 2 O \u003d 2H 2 SiF 6 + H 2 SiO 2
H 2 SiF 6 is close in strength to sulfuric acid, salts are fluorosilicates.

Application:

Silicon finds the greatest use in the production of alloys for giving strength to aluminum, copper and magnesium and for the production of ferrosilicides, which are important in the production of steels and semiconductor technology. Silicon crystals are used in solar cells and semiconductor devices - transistors and diodes. Silicon also serves as a raw material for the production of organosilicon compounds, or siloxanes, obtained in the form of oils, lubricants, plastics and synthetic rubbers. Inorganic silicon compounds are used in ceramic and glass technology, as an insulating material and piezocrystals.

For some organisms, silicon is an important biogenic element. It is part of the supporting structures in plants and skeletal structures in animals. In large quantities, silicon is concentrated by marine organisms - diatoms, radiolarians, sponges. Large amounts of silicon are concentrated in horsetails and cereals, primarily in the Bamboo and Rice subfamilies, including common rice. Human muscle tissue contains (1-2) 10 -2% silicon, bone tissue - 17 10 -4%, blood - 3.9 mg / l. With food, up to 1 g of silicon enters the human body daily.

Antonov S.M., Tomilin K.G.
KhF Tyumen State University, 571 groups.

Sources: Silicon. Wikipedia; Silicon in the Online Encyclopedia "Krugosvet" , ;
Silicon site