One of the most sought after in the technology and industrial elements is silicon.This it owes its unusual properties.Today, there are a lot of different compounds of this element, which play an important role in the synthesis and the creation of technical products, glassware, glass, hardware, building materials, jewelry and other industries.
General characteristics of silicon
If we consider the position of silicon in the periodic system, then we can say this:
- Located in Group IV main group.
- Number 14.
- atomic mass of 28.086.
- chemical symbol Si.
- name - silicon, or in Latin - silicium.
- electronic configuration of the outer layer 4e: 2e: 8e.
Crystalline silicon is similar to the diamond lattice.The nodes of the atoms are located, type it - a face-centered cubic.However, due to the greater length of the relationship between physical properties of silicon are very different from the properties of the allotropic modification of carbon.
Physical and chemical properties
There are two allotropic modifications of this item: amorphous and crystalline.They are very similar.However, as in the case of other substances, the main difference between them - the crystal lattice of silicon.
Thus both versions - a different color powders.
1. Crystalline silicon is a shiny dark gray powder resembling metal.Its structure corresponds to the diamond, but the properties are different.It has:
- fragility;
- low hardness;
- semiconductor properties;
- melting 14150S;
- density of 2.33 g / cm3;
- boiling point 27000S.
Its reactivity is low compared to other allotropic form.
2. Amorphous silicon - the brown-brown powder, has a structure silnorazuporyadochennogo diamond.The chemical activity is high enough.
In general, it should be noted that react silicon dislikes.To make him responsive, necessary temperature is not less than 400-5000S.Under these conditions the formation of various chemical compounds of silicon.Such as:
- oxides;
- halides;
- suicides;
- nitrides;
- borides;
- carbides.
possible interaction of silicon with nitric acid or alkali, which is the name of the etching process.Widespread silicones, which today are becoming more common.
Being in nature
Silicon in nature is contained in an amount sufficient weight.It is in second place after oxygen prevalence.Its mass fraction is about 30%.Seawater also contains an active element in a concentration of 3 mg / L.Therefore, we can not say that silicon in nature - it is a rare item.
On the contrary, there are a lot of different rocks and minerals, as part of which it is found and from which it can produce.The most common natural compounds of silicon following:
- Silica.The chemical formula of SiO2.There is quite a diversity of minerals and rocks on its base: sand, flint, feldspar, quartz, rock crystal, amethyst, chalcedony, carnelian, opal, jasper, and others.
- silicates and aluminum silicates.Kaolin, feldspar, mica, silicic acid salts, talc, asbestos.
thus spread widely in the nature of silicon and its compounds are popular and in demand by people for use in technical purposes.
Silicon and its compounds
Since the element of pure form can not exist, so important are its different compounds.From a chemical point of view, it can be three degrees of oxidation: 2, 4, -4.For this reason, and also because of their inertia, but especially on the structure of the crystal lattice, it creates the following main types of substances:
- binary compounds with non-metals (silane, carbide, nitride, phosphide, and so on;
- oxides;
- siliconacid;
- metal silicates.
Let us consider how important the silicon and its compounds, are the most common and popular for people.
silicon oxide
There are two types of substances expressed by the formula:
- SiO;
- SiO2.
However, the most widely used is silica. It exists in nature in the form of a very beautiful semi-precious stones:
- agate;
- chalcedony;
- opal;
- carnelian;
- jasper;
- amethyst;
- rhinestone.
The use of silicon in a form found its application in the manufacture of jewelry.Incredibly beautiful gold and silver jewelry made with these semi-precious and precious stones.
few more variations of the silica:
- quartz;
- river and silica sand;
- flint;
- feldspars.
The use of silicon in such types implemented construction works, engineering, electronics, chemical industry, metallurgy.Together listed oxides are single substances - silica.
silicon carbide and its application
Silicon and its compounds - a material of the future and the present.One such material is silicon carbide or carbide of the element.The chemical formula SiC.It occurs in nature as the mineral moissanite.
Pure compound of carbon and silicon - a beautiful clear crystals, diamond-like structure.However, for industrial purposes used painted in green and black color material.
main characteristics of the substance can be used in metallurgy, machinery, chemical industry, the following:
- semiconductor wide-band;
- very high strength (7 on the Mohs scale);
- resistant to high temperatures;
- excellent elektroustoychivost and thermal conductivity.
This allows the use of silicon carbide as the abrasive material in metallurgy and chemical synthesis.And on this basis to make a broad-spectrum LEDs, parts to the glass furnaces, nozzles, torches, jewelry (cubic zirconia moissanite valued above).
strength and its value
hydrogen compounds of silicon is called silane and can not be obtained by direct synthesis of the starting materials.To obtain the various metal silicides are used, which are treated with acids.As a result, the silane gas is released and forms a metal salt.
Interestingly, the present compound has never produced alone.Always by reacting a mixture of mono-, di- and trisilana, in which the silicon atoms are connected together in a chain.
The properties of these compounds - strong reducing agents.Sami thus easily oxidized by oxygen, sometimes with the explosion.With halogens Violent reactions always with a great burst of energy.
Applications silanes following:
- organic synthesis reactions, resulting in the formation of important silicones - silicone, rubber, sealants, lubricants and other emulsions.
- Microelectronics (LCD monitors, integrated circuit engineering, etc.).
- high purity polysilicon.
- Dental prosthetics.
Thus, the value of silanes in the modern world is high.
The silica and silicates
hydroxide of the element - they are different silicas.Allocate:
- meta;
- ortho;
- polysilicon and other acids.
All they share common characteristics - the extreme imbalance in the free state.They are easily decomposed by heat.Under normal conditions, there are short, turning first to the sol, and then a gel.After drying, the silica gels, such structures are called.They are used as adsorbents in the filter.
important from the point of view of the industry, are salts of silicic acids - silicates.They are the basis of the preparation of such substances as:
- glass;
- concrete;
- cement;
- zeolite;
- kaolin;
- porcelain;
- faience;
- crystal;
- ceramics.
alkali metal silicates - soluble, all the rest - no.Therefore, sodium silicate and potassium called liquid glass.Normal office glue - this is the sodium salt of silicic acid.
But the most interesting compounds are still glass.There are all variants of the substance or idea!Today, given colored, optical, matte options.Glassware impresses with its splendor and diversity.When adding certain metal and nonmetal oxides to the mixture can obtain a variety of types of glass.Sometimes even the same composition, but different percentages of the components leads to a difference in the properties of the substance.Examples are china and earthenware, that formula SiO2 * AL2O3 * K2O.
Quartz glass - is a form of high-purity product, the composition of which is described as silica.
discoveries in the field of silicon compounds
Over the past few years, studies have shown that silicon and its compounds - the most important participants in the normal state of living organisms.With the lack or excess of the element associated diseases such as:
- cancer;
- tuberculosis;
- arthritis;
- cataracts;
- leprosy;
- dysentery;
- rheumatism;
- hepatitis and others.
themselves aging processes are also associated with quantitative content of silicon.Numerous experiments on mammalian animals proved that the shortage element having heart attacks, strokes, cancer, and hepatitis A virus is activated.
