Scheme of the structure of silicon. Electron shell structure
Atomic structure Position in PS: Period III; group IV, leading; Kernel charge: +14 Si; Relative atomic mass: Ar (Si) = 28 Atomic structure: p = 14, e = 14, n = = 14 Electronic formula: +14 Si 2e; 8e; 4e; +14 Si 1s 2 2s 2 2p 6 3s 2 3p Si 1s 2 2s 2 2p 6 3s 2 3p 2 Nemetall;
Atomic properties Si e reducing agent + 4 e oxidizer Si + 4 Si -4 Silicon, giving all external electrons to more EO elements, is oxidized, passing into Si + 4; Taking 4 electrons to its external energy level, it is reduced to Si-4;
Physical properties of silicon Silicon is a non-metal, it exists in a crystalline and amorphous state. Crystalline silicon is a grayish-steel substance with a metallic luster, very hard but fragile. Amorphous silicon - brown powder. p = 2.33 g / cm 3; t pl. = C; t kip. = C;
Crystal structure of silicon A crystal lattice of silicon is a cubic face-centered diamond type. But due to the longer bond length between Si - Si, the hardness of silicon is significantly less than that of diamond. Silicon is fragile only when heated above C.
Electro physical properties Elemental silicon Elemental silicon is a typical semiconductor. typical semiconductor. The electrophysical properties of crystalline silicon are greatly influenced by trace impurities contained in it. To obtain silicon single crystals with p-type conductivity, additives of elements of the 3rd group of boron, aluminum, gallium and indium, with electronic conductivity of the additive, are introduced into silicon elements V phosphorus, arsenic or antimony groups.
Flint Flint, this Flint, this ugly and very ugly and very durable stone, durable stone, laid the foundation for a stone beginning of the stone age - the century - the century of flint working tools. flint tools. There are two reasons: - the prevalence and availability of silicon; - the prevalence and availability of silicon; - the ability to form sharp cutting edges when chipped; - the ability to form sharp cutting edges when chipped;
Do you know that .. The method for obtaining silicon in its pure form was developed by Nikolai Nikolayevich Beketov. Silicon in Russia is produced in factories: Kamensk - Uralsky (Sverdlovsk Region). Kamensk - Uralsky (Sverdlovsk Region) Shelekh (Irkutsk Region). Shelekh (Irkutsk region).
Production of silicon In the industry, silicon is obtained by reducing the melt of SiO 2 by coke at t = C in arc furnaces. The purity of the silicon thus obtained is 99.9%.
Obtaining silicon Laboratory production method: SiO Mg 2MgO + Si SiO Mg 2MgO + Si
Chemical properties of silicon When heated to 400 - C, silicon reacts with oxygen to form silicon dioxide: Si + O 2 SiO 2 Si + O 2 SiO 2
Properties of CO 2 CO 2 SiO 2 oxide Acid oxide Molecular crystal lattice Atomic Colorless gas. Crystalline, solid, refractory. Chemical Chemical Properties H 2 O + CO 2 = H 2 CO 3 Does not react CO 2 + CaO = CaCO 3 SiO 2 + CaO = CaSiO 3 CO 2 + Ca (OH) 2 = CaCO 3 + H 2 O SiO 2 + NaOH = Na 2 SiO 3 + H 2 O CO 2 + 2Mg = 2MgO + C SiO 2 + 2C = 2MgO + Si C + CO 2 = 2CO SiO 2 + 2C = Si + 2CO
Properties of acids H 2 CO 3 H 2 SiO 3 Dibasic, oxygen-containing, weak, fragile, since flying. Dibasic, oxygen-containing, weak, insoluble in water. Receiving: CO 2 + H 2 O = H 2 CO 3 Receiving: SiO 2 + H 2 O = cannot Unstable, fragile, decomposes when standing or heated: H 2 CO 3 = CO 2 + H 2 O Can not be selected in its pure form, because decomposes when heated: H 2 SiO 3 = SiO 2 + H 2 O Zn + H 2 CO 3 = ZnCO 3 + H 2 Minor gas evolution __________
Silicic Acid Carbonic Acids - Carbonates; - hydrocarbons; - silicates; - silicates; Carbonates have all the properties of salts, are strong electrolytes, completely dissociate into ions (soluble in water). Only alkali metal salts are soluble, the others form insoluble or do not form salts at all (Al +3, Cr +3, Ag +).
Biological role The most important silicon compound, SiO 2, is essential for plant and animal life. Thanks to him, reeds, reeds Thanks to him, reeds, reeds and horsetails stand firmly like bayonets. and horsetails stand tight, like bayonets. Sharp sedge leaves cut like Sharp sedge leaves cut like knives, stubble on a mowed field knives, stubble on a mowed field pricks like needles, and stalks of cereals stick like needles, and the stalks of cereals are so strong that they do not allow so strong that do not allow the field in the fields to fall from the rain and the wind field in the fields to go from the rain and the wind
Silicon is a trace element that is constantly contained in the human body. Its greatest amount is contained in the lymph nodes, connective tissue of the aorta, trachea, hair and skin. Silicon is needed to build epithelial cells. Silicon is a trace element that is constantly contained in the human body. Its greatest amount is contained in the lymph nodes, connective tissue of the aorta, trachea, hair and skin. Silicon is needed to build epithelial cells. Silicon plays an important role in the process of bone mineralization; necessary to maintain the elasticity of the arterial wall, has a positive effect on the immune system and slows the aging process in the tissues of the human body. The average content of silicon in the blood is 8.25 mg / day. With age, its level in the body decreases, so in elderly people, the need for silicon tends to increase. Improve the absorption of silicon by the body the presence of calcium, magnesium, manganese and potassium. Silicon plays an important role in the process of bone mineralization; necessary to maintain the elasticity of the arterial wall, has a positive effect on the immune system and slows the aging process in the tissues of the human body. The average content of silicon in the blood is 8.25 mg / day. With age, its level in the body decreases, so in elderly people, the need for silicon tends to increase. Improve the absorption of silicon by the body the presence of calcium, magnesium, manganese and potassium.
The biological role of silicon is also included in the composition of lower living organisms — diatoms and radiolarians — the most delicate lumps of living matter, which create their unsurpassed beauty skeletons made of silica. Silicon is also part of the lower living organisms - diatoms and radiolarians - the most delicate lumps of living matter, which create their unsurpassed beauty of silica skeletons. Diatoms Radiolaria Self-control 1. What is the place of silicon in the periodic system: a) 2 period, 4 og. b) 3 period, 3 gr. chapter. c) 3 period, 4 gr. chapter) 2 period, 4 gr. b) 3 period, 3 gr. chapter. c) 3 period, 4 gr. chapter. 2. Silicon lattice: a) ionic; b) atomic; c) molecular; a) ionic; b) atomic; c) molecular; 3. According to the prevalence in nature of silicon ... element: a) first; b) the second; c) the third; a) the first; b) the second; c) the third; 4. Silicon reacts with: a) metals, hydrogen, halogens; a) metals, hydrogen, halogens; b) metals, halogens, easily soluble in alkalis; b) metals, halogens, easily soluble in alkalis; c) oxides, acids, non-metals. c) oxides, acids, non-metals. 5. Silicic acid salts: a) silicides; b) hydrosilicates; c) silicates; a) silicides; b) hydrosilicates; c) silicates;
Silicon.
Silicon - an element of the main subgroup IV of the group of the 3rd period of the periodic system of chemical elements DI Mendeleev, with atomic number 14, atomic mass: 28.0855. In compounds, it usually exhibits a degree of oxidation of +4 (valence IV) and very rarely +3, +2, and +1 (valences, respectively, III, II, and I). In the periodic table, Mendeleev silicon is located in group IVA (A-indicates that this is the main subgroup) (in the carbon group), in the third period. Non-metal . Denoted by symbol Si(lat Siliconium). In free form - brown powder or light gray compact material with a metallic sheen. Lattice structure: cubic, diamond.
Main state: + 14 Si 14 e 1s 2 2s 2 2p 6 3s 2 3p 2, p-element.
2. Physical properties.
Crystalline silicon is a dark gray substance with a steel luster. The structure of silicon is similar to the structure of diamond. In its crystal, each atom is surrounded by tetrahedral four others and is connected with them by a covalent bond, which is much weaker than between carbon atoms in a diamond. In a silicon crystal, even under normal conditions, some of the covalent bonds are destroyed. Therefore, it has free electrons, which cause a small electrical conductivity. When lighting and heating increases the number of broken bonds, which means that the number of free electrons increases and the electrical conductivity increases. So should explain the semiconductor properties of silicon.
Silicon is very fragile, its density is 2.33 g / cm3. Like coal, refers to refractory substances.
Silicon consists of three stable isotopes: 2814Si (92.27%), 2914Si (4.68%), and 3014Si (3.05%).
3. Being in nature.
Most often in nature, silicon is found in the form silica - compounds based on silicon dioxide (IV) SiO2 (about 12% of the mass of the earth's crust). The main minerals and rocks formed by silicon dioxide are sand (river and quartz), quartz and quartzite, flint, and feldspar. Natural silicates have a complex composition and structure. Here is the composition of some natural silicates:
ü feldspar K 2 O × Al 2 O 3 × 6SiO 2,
ü asbestos 3MgO × 2SiO 2 × 2H 2 O,
ü mica K 2 O × 3Al 2 O 3 × 6SiO 2 × 2H 2 O,
ü kaolinite 3Al 2 O 3 × 2SiO 2 × 2H 2 O.
The second most common group in nature of silicon compounds is silicates and aluminosilicates
Single facts of finding pure silicon in the native form are noted.
4. Chemical properties of silicon and its compounds.
By chemical properties silicon, like carbon, is a non-metal, but its non-metal is less pronounced, since it has a larger atomic radius. Since silicon atoms have 4 electrons on the outer energy level, the oxidation state of both -4 and +4 is characteristic of silicon (a silicon compound is known, where its degree of oxidation is +2).
Silicon under normal conditions is rather inert, which should be explained by the strength of its crystal lattice. It directly interacts only with fluorine:
Acids (except mixture of hydrofluoric HF and nitric HNO 3)silicon does not act. However, it dissolves in alkali metal hydroxides, forming silicate and hydrogen:
Of the two allotropic modifications of silicon, crystalline and amorphous, amorphous silicon is more chemically active. He reacts with with oxygen when heated, forming SiO 2:
as well as with all halogens, eg:
At high temperature silicon connects with carbonforming the carborundum SiC:
Carborundum has a diamond-like crystal lattice, in which each silicon atom is surrounded by four carbon atoms and vice versa, and covalent bonds are very strong, as in diamond. Therefore, in hardness it is close to diamond. Grinding stones and grinding wheels are made from silicon carbide.
Magnesium silicide. In reactions with active metals, occurring with the formation of silicides, Silicon acts as an oxidizing agent:
At high temperatures, silicon recovers many metals from their oxides. (!!!)
Silane Under the action of hydrochloric acid on silicides, the simplest hydrogen compound of silicon is silane SiH 4:
Silane is a poisonous gas with an unpleasant odor, self-igniting in air (!!!):
Silicon oxide (IV).Silicon oxide (IV) is also called silica. It is a solid refractory substance. (melting temperature 1700 ° C) widespread in nature in two forms:
1) crystalline silica - in the form of a mineral of quartz and its varieties (rock crystal, chalcedony, agate, jasper, flint); quartz forms the basis of quartz sands widely used in construction and silicate industry;
2) amorphous silica - in the form of the opal mineral composition SiO 2 × P H 2 O; the earthy forms of amorphous silica are diatomite, tripoli (infusorial earth); An example of artificial amorphous anhydrous silica is silica gel, which is obtained from sodium metasilicate:
Silica gel has a developed surface and therefore absorbs moisture well. .
At 1710 ° quartz melts. With the rapid cooling of the molten mass is formed quartz glass . It has a very low coefficient of expansion, so that hot quartz glass does not crack when the water is rapidly cooled. Laboratory glassware and instruments for scientific research are made from quartz glass.
The simplest formula of silicon oxide (IV) SO 2 is similar to the formula of carbon monoxide (IV) CO 2. Meanwhile, their physical properties are very different (SiO 2 - solid, CO 2 - gas). This difference is due to the structure of the crystal lattices. C0 2 crystallizes in the molecular lattice, SiO 2 - in the atomic. The structure of SiO 2 in a planar image can be represented as follows:
The coordination number of a carbon atom in solid CO 2 is 2, and silicon in SiO 2 is 4. Each silicon atom is enclosed in a tetrahedron of 4 oxygen atoms. At the same time, the silicon atom is in the center, and oxygen atoms are located on the tops of the tetrahedron . The entire piece of silica can be considered as a crystal whose formula is (SiO 2) n. This structure of silicon oxide (IV) determines its high hardness and refractoriness .
Chemical properties of silicon oxide (IV) SiO 2 refers to acid oxides. When fusing it with solid alkalis, basic oxides and carbonates, silicic acid salts are formed:
Only hydrofluoric acid interacts with silicon oxide (IV):
This reaction is used to etch glass. .
Silicon (IV) does not dissolve in water and does not chemically interact with it. (!!!) Therefore, silicic acid is obtained indirectly by acting with an acid on a solution of potassium or sodium silicate:
In this case, silicic acid (depending on the concentration of the initial solutions of salt and acid) can be obtained both in the form of a gelatinous mass containing water, and in the form of a colloidal solution (sol).
Silicic acid. SiO 2 is the anhydride of a number of silicic acids, whose composition can be expressed by the general formula: xSiO 2 × yH 2 O, where x and y - whole numbers:
1) x = 1, y = 1: SiO 2 × H 2 O, i.e. H 2 SiO 3 - metasilicic acid;
2) x = 1, y = 2: SiO 2 × 2H 2 O, i.e. H 4 SiO 4 - orthosilicic acid;
3) x = 2, y = 1: 2SiO 2 × H 2 O, i.e. H 2 Si 2 O 5 - bimetacrynic acid.
Silicic acid is built from tetrahedral structural units (in each such unit, the silicon atom is in the center of the tetrahedron, and there are oxygen atoms in the tops). Structural links, uniting in chains, form more stable polysilicon acids:
The composition of such compounds can be expressed by the formula (H 2 SiO 3) n. However, usually silicic acid is represented by the formula H 2 SiO 3. H 2 SiO 3 - the acid is very weak, little soluble in water. When heated, it easily decomposes like carbonic acid:
All silicic acids are very weak (weaker than coal).
Silicates. The salts of all silicic acids are calledsilicates, although, as a rule, in educational literature, silicates imply salts of methacilicic acid. Their composition is usually represented by the formula in the form of compounds of oxides of elements. For example, calcium silicate CaSiO 3 can be expressed as: CaO × SiO 2.
The silicates of the composition R 2 O × nSiO 2, where R 2 O - oxides of sodium or potassium , are called soluble glass , but their concentrated aqueous solutions - liquid glass . Sodium soda glass is most important..
When standing in air, the solutions of silicates grow turbid, since carbon dioxide (IV) in the air displaces silicic acid from its salts:
Silicic acid is practically insoluble in water - this property is used as a qualitative reaction to the ion SiO 3 2-.
Silicates are obtained by fusing silica with alkalis or carbonates:
5. Discovery of the ion SiO 3 2. (I can not find anything ...)
6. The role of silicon compounds in soil formation and forestry.
The igneous rocks are fairly stable in their composition and contain mainly compounds of silicon, aluminum, iron, alkalis, magnesium and calcium. According to the Si0 2 content, igneous rocks are divided into four groups: acidic (\u003e 65%), medium (52-65%), basic (40-52%) and ultrabasic (<40 %). Наиболее представительны две большие группы: кислые и основные породы. Как будет видно в дальнейшем, при характеристике многих типов почв именно этот фактор приуроченности почв к кислым или основным магматическим почвообразующим породам является решающим в отношении генезиса, эволюции и свойств почв.
Acid igneous rocks- granites, pegmatites, rhyolites, dacite and others - usually have a light and brownish color with pronounced crystals of quartz, feldspar, mica. The SiO 2 content in them is high (more than 65%) with a significant amount of potassium and sodium. At the same time, little iron, and calcium and magnesium are negligible. Soils on acidic igneous rocks, for example, on granites, differ in the early stages of weathering by friability, gravel character of the source material. When weathered under humid conditions, they easily lose alkaline-earth elements, as a result of which the soil on such weathered substrates (eluvium of rocks) is extremely poor, poorly fertile.
Main igneous rocks -basalt, gabbro, etc., as a rule, have a dark (to black) color. They are characterized by a lower SiO 2 content compared to acidic rocks. The main igneous rocks are relatively rich in compounds of iron, manganese, chromium, cobalt, zinc, titanium, nickel, copper. The products of their weathering quite quickly acquire a clay character, retain an alkaline and neutral reaction for a long time, and are distinguished by an increased content of humus and clay minerals. The soil on such rocks are more fertile.
In addition to acidic and basic species are often found igneous rocks of transitional type(medium) - intrusive rocks of the diorite group and their effusive counterparts - andesites. Accordingly, the soils on these rocks acquire features similar to those confined to acidic or basic rocks. Much less common ultrabasic breeds:peridotites and picrites, which have the lowest SiO 2 content.
Metamorphic rocks -transitional between massive crystalline and sedimentary rocks. The ancient sedimentary rocks under diving, high pressure and temperatures are metamorphosed, forming gneisses, serpentinites, marble, quartzites, shale. Gneisses are particularly similar in composition to granites. The soils that form on such rocks have similar features to the soils on the acidic igneous rocks themselves.
Chlorine.
1. The position of aluminum in the table DI Mendeleev. The structure of the atom, manifested degree of oxidation.
Chlorine - an element of the main subgroup of the VII group, the 3rd period, with atomic number 17. It is denoted by the symbol Cl (lat. Chlorum). Chemically active non-metal . Included in the halogen group .
Simple substance chlorine under normal conditions - poisonous gas yellowish-green color is heavier than air, with a strong odor . Diatomic chlorine molecule (formula Cl 2).
Main state: +17 Cl 17e1s 2 2s 2 2p 6 3s 2 3p 5, p-element. Art .: -1 +1 +3 +5 +7.
The structure of the electron shell.
At the valence level of the chlorine atom contains 1 unpaired electron : 1s 2 2s 2 2p 6 3s 2 3p 5, so the valence of 1 for a chlorine atom is very stable. Due to the presence in the chlorine atom of the unoccupied d-sublevel orbitals, the chlorine atom can exhibit other degrees of oxidation. Scheme of formation of excited states of the atom:
Chlorine compounds are also known in which the chlorine atom formally exhibits valence 4 and 6, for example ClO 2 and Cl 2 O 6. However, these compounds are radicals, that is, they have one unpaired electron.
2. Physical properties.
Under normal conditions, chlorine is a yellow-green gas with a suffocating odor. Some of its physical properties are presented below.
Density: 3.214 g / l, liq. - at -35 ° C - 1.557, TV. at -105 0 С- 1.9 g / cm 3.
Melting point: 172.2 K
Boiling point: 238.6 K
Heat of fusion: 6.41 kJ / mol
Heat of evaporation: 20.41 kJ / mol.
Chlorine gas is relatively easy to liquefy. Starting with a pressure of 0.8 MPa (8 atmospheres), chlorine will be liquid already at room temperature. When cooled to a temperature of −34 ° C, chlorine also becomes liquid at normal atmospheric pressure. Liquid chlorine is a yellow-green liquid with a very high corrosive effect (due to a high concentration of molecules). Increasing the pressure, you can achieve the existence of liquid chlorine up to a temperature of +144 ° C (critical temperature) at a critical pressure of 7.6 MPa. In terms of electrical conductivity, liquid chlorine takes place among the strongest insulators: it conducts current almost a billion times worse than distilled water, and 10 22 times worse than silver. The speed of sound in chlorine is about one and a half times less than in air.
3. Being in nature.
In nature, there are two isotopes of chlorine 35 Cl and 37 Cl. Chlorine is the most common halogen in the earth's crust. . Chlorine is very active - it directly connects with almost all elements of the periodic system. Therefore, in nature, it is found only in the form of compounds in the composition of minerals:
ü halite NaCl,
ü sylvina KCl,
ü sylvinite KCl · NaCl,
ü bischofite MgCl 2 · 6H 2 O,
ü carnallite KCl · MgCl 2 · 6H 2 O,
ü Cainite KCl · MgSO 4 · 3H 2 O.
The largest reserves of chlorine are contained in salts, waters, seas and oceans (the content in sea water is 19 g / l). Chlorine accounts for 0.024% of the total number of atoms in the earth's crust; clarke number (numbers expressing the average content of chemical elements in the earth's crust, hydrosphere, Earth, space bodies, geochemical or cosmochemical systems, etc., relative to the total mass of this system. It is expressed in% or g / kg.) chlorine - 0.017%. The human body contains 0.25% chlorine ions by weight. In humans and animals, chlorine is found mainly in the intercellular fluids (including blood) and plays an important role in the regulation of osmotic processes, as well as in processes associated with the work of nerve cells.
4. Chemical properties of chlorine and its compounds. Getting chlorine.
The structure of the silicon atom. Si. +14. Excited state. E. 3d. 3p. 3s. E. 3d. 3p. 3s. 1s 2s 2p 3s 3p. 2e 8e 4e. 2. 2. 6. 2. 2.
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"Silicon and its compounds" - The structure and properties of atoms. Semiconductor. t melt (Si) = 1415? C, t melt (diamond) = 3730? C. Getting silicon. The discovery of silicon. Included also in the composition of plants and animals. The physical properties of silicon. Hence, the brick is ceramics, and the tiles and fragments of ancient Greek amphora are also ceramics. Objectives: The chemical properties of silicon.
"Silicon compounds" - Silicon and its compounds. Chemical properties of SiO2. Silane Getting silicic acid. Silicon properties. Silicon oxide. Natural silicates. Oxidation state Rhinestone. Topaz. Getting silicon in the laboratory. Being in nature. Crystal lattices. The discovery of silicon. Amethyst. Getting silicon.
"Silicon isotopes" - Separation of silicon isotopes. Production of polycrystalline silicon. Prospects for the use of monoisotopic silicon. Isotopic dilution when growing a single crystal from a quartz crucible. Production of single crystal seed. Dependence of the position of the maximum of the Raman band on atomic mass.
"Silicon Lesson" - Which of the most important chemical elements in living and non-living nature? Oxides of carbon and silicon. The substance is transparent. On the manifestation of non-metallic and metallic properties. Summing up the reflection. Final testing. Oxides of carbon and silicon hydroxides? The state of aggregation: a) liquid, b) gas, c) solid.
"Silicon" - Silicon is a simple substance. Physical properties. Silicon oxide (IV). Silicides Meaning for living organisms. Interaction with metals. Interaction with non-metals. Silicon carbide. Silicon in nature. Silicon. Products of silicate industry. One of the types of natural silicon compounds is silicates.
"Carbon and silicon" - Silicon oxide (IV). Elements of group IV of the main subgroup. Toxicity. 7. Interesting about carbon. Silicates. Slip to the touch. Diamond is the hardest natural substance. Chemical properties. More than 99% of carbon in the atmosphere is in the form of carbon dioxide. Carbides. 6. Application. One of the softest among solids.
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