Chemical properties of Si 5, Chemical properties of Si

Silicon has two allotropic forms, crystalline and amorphous. Crystalline silicon is further divided into monocrystalline silicon.

and polysilicon, both of which have diamond.

Lattice, the crystal is hard and brittle, has a metallic luster, can conduct electricity, but the conductivity is not as good as that of metal, and increases with the increase of temperature, and has semiconductor properties. The melting point of crystalline silicon is 1410C, the boiling point is 2355C, and the amorphous silicon is a black-gray powder.

Chemical properties of silicon.

Silicon is inactive at room temperature, and its main chemical properties are as follows:

1) Interaction with non-metals.

Si can only react with F2 at room temperature, and burns instantaneously in F2 to generate SiF4

si+f2 === si+f4

When heated, it can react with other halogens to form silicon halide, and react with oxygen to form SiO2:

Si+2F2 SiF4 (X=Cl,Br,I)Si+O2 SiO2 SiO2 (Microstructure of SiO2) At high temperatures, silicon is combined with non-metallic elements such as carbon, nitrogen, and sulfur to form silicon carbide, respectively.

SiC, silicon nitride.

Si3N4 and silicon sulfide SiS2, etc.

si+c sic

3si+2n2 si3n4

si+2s sis2

2) Interaction with acids.

Si is passivated in oxygenated acids, but with hydrofluoric acid.

and its mixed acid reaction to generate SIF4 or H2SIF6:

si+4hf sif4↑+2h2↑

3si+4hno3+18hf === 3h2sif6+4no↑+8h2o

3) Interaction with alkali.

Amorphous silicon reacts violently with alkali to form soluble silicate.

And release hydrogen:

Si + 2NaOH + H2O === Na2SiO3 + 2H2 4) and metal.

Silicon can also be combined with calcium, magnesium, copper, iron, platinum, bismuth, etc., to form corresponding metal silicides.

Uses of silicon.

Episode 6: What are the chemical properties of a substance: This lesson introduces the definition of the chemical properties of a substance through three experiments: "iron rusting", "candle burning", and "copper sulfate reacts with sodium hydroxide". The properties of matter that manifest themselves in chemical changes are called chemical properties.

The Si chemical element is silicon.

Silicon (silicon) is a chemical element, the chemical symbol is SI, formerly known as silicon. Atomic number 14, relative to the atomic mass, there are two allotropes of amorphous silicon and crystalline silicon, which belong to the third period on the periodic table, the metalloids of group IVA. Silicon is also an extremely common element, yet it is rarely found in nature in its elemental form.

Chemical properties of silicon.

Silicon has obvious non-metallic properties and can be dissolved in alkali metal hydroxide solutions to produce (meta)silicates and hydrogen. The silicon atom is located in the ivth main group of the periodic table, it has an atomic number of z=14 and 14 electrons outside the nucleus. Electrons are outside the nucleus, according to the energy level from low silicon atoms to high, from the inside to the outside, layer by layer, which is called the shell structure of electrons.

The outer nuclear electrons of the silicon atom have 2 electrons in the first shell and 8 electrons in the second shell, reaching a stable state. The outermost four electrons are the valence electrons, which play a leading role in the conductivity of silicon atoms. Because the silicon atom has such a structure, it has some special properties:

The 4 outermost valence electrons keep the silicon atoms in a metastable structure, and these valence electrons cause the silicon atoms to be covalently bonded to each other.

Since the covalent bond is relatively strong, silicon has a high melting point and density;The chemical properties are relatively stable, and it is difficult to react with other substances (except hydrogen fluoride and lye) at room temperatureThere are no obvious free electrons in silicon crystals, which can conduct electricity, but the conductivity is not as good as that of metals, and it increases with the increase of temperature, and has semiconductor properties.

The above content reference:Encyclopedia – Silicon

SIH4 is a silane (hydrogen silicon).

Silane, a compound of silicon and hydrogen, is a general term for a series of compounds, including sillane (siH4), ethylsilane (si2H6) and some higher silicon-hydrogen compounds. At present, the most widely used is sillane. Generally, methyl silane is referred to as silane.

Chemical Properties:

Both ignition and ** of silanes are the result of reaction with oxygen. Silanes are extremely sensitive to oxygen and air. Silanes with a certain concentration will also react with oxygen at a temperature of -180.

Solid silanes react with liquid oxygen very dangerously. When the silane is burned, the rolling flame is dark yellow and reacts under the condition of sufficient oxygen

sih4+ 2o2=sio2+ 2h2o δh= -362 kcal/ mol。

If there is not enough oxygen, there is an incomplete oxidation reaction

sih4+ o2=sio2+ 2h2 δ h= -226 kcal/ mol。

The high temperature generated by combustion also causes the thermal decomposition reaction of the unreacted silane

sih4 =si+ 2h2 δh= -8. 2 kcal/ mol。

Refer to the above content: Encyclopedia-sih4

sih4 isSilanes(Hydrogen silicon). Model Qi loss

Silane, a compound of silicon and hydrogen, is a general term for a series of compounds, including sillane (siH4), ethylsilane (si2H6) and some higher silicon-hydrogen compounds. At present, the most widely used is methicandane. Generally, sillane is abbreviated as silane.

Chemical Properties:

Both ignition and ** of silanes are the result of reaction with oxygen. Silanes are extremely sensitive to oxygen and air. Silanes with a certain concentration will also react with oxygen at a temperature of -180. Solid silane with liquid oxygen.

The reaction is very dangerous. When the silane is burned, the flame is dark yellow and reacts under conditions of sufficient oxygen

sih4+ 2o2=sio2+ 2h2o δh= -362 kcal/ mol。

If there is not enough oxygen, there is an incomplete oxidation reaction.

Occurrence: SIH4 + O2 = SiO2 + 2H2 δ H= -226 kcal mol.

The high temperature generated by combustion also causes the thermal decomposition reaction of some unreacted silanes

sih4 =si+ 2h2 δh= -8. 2 kcal/ mol。

Refer to the above content: Encyclopedia-sih4

SI stands for the element silicon. The element symbol of silicon is Si, which represents an atom of the silicon element on a microscopic level and the chemical element silicon on a macroscopic level. Silicon rarely occurs in nature in the form of elemental matter, generally in rocks, gravel, dust, in the form of complex silicates or silica.

The role of SIThe production of silicone rubber, silicone resin, silicone oil and other silicone silicone rubber has good elasticity and high temperature resistance, and is used to make medical supplies, high-temperature resistant gaskets, etc. Silicone resin is used in the production of insulating paints, high-temperature coatings, etc. Silicone oil is an oily substance, its viscosity is less affected by temperature, used in the production of advanced lubricants, glazing agents, fluid springs, dielectric liquids, etc., and can also be processed into colorless and transparent liquids, as a high-grade waterproofing agent sprayed on the surface of buildings.

The manufacture of high-purity semiconductors and modern large-scale integrated circuits are almost all made of high-purity silicon metal, and high-purity silicon metal is also the main raw material for the production of optical fibers, so it can be said that silicon metal has become the basic pillar industry of the information age.

Physical properties: There are two allotropic forms of amorphous silicon and crystalline silicon. Crystalline silicon is gray-black, amorphous silicon is black, density grams cubic centimeters, melting point 1410, boiling point 2355, crystalline silicon belongs to atomic crystals.

Insoluble in water, nitric acid and hydrochloric acid, soluble in hydrofluoric acid and lye. Hard and metallic.

Chemical properties: Silicon has obvious non-metallic properties, which can be dissolved in alkali metal hydroxide solutions to produce (meta)silicate and hydrogen. Under heating, it can interact with non-metals such as elemental halogen, nitrogen, carbon, etc., and can also interact with some metals such as mg, ca, fe, pt, etc.

Silicide is generated.

Insoluble in general inorganic acids, soluble in alkali solution, and hydrogen gas is released to form the corresponding alkali metal silicate solution, which can interact with water vapor at red hot temperature.

Crystalline silicon is gray-black, amorphous silicon is black, density gram cubic centimeter, melting point 1414, boiling point 2900, crystalline silicon belongs to atomic crystals, hard and metallic luster, with semiconductor properties. The chemical properties of silicon are relatively active, it can be combined with oxygen and other elements at high temperatures, insoluble in water, nitric acid and hydrochloric acid, soluble in hydrofluoric acid and lifting lye, used in the manufacture of alloys such as ferrosilicon, silicon steel, etc., monocrystalline silicon is an important semiconductor material, used in the manufacture of high-power transistors, rectifiers, solar cells, etc. At room temperature, the intrinsic dry brigade concentration is that silicon is widely distributed in nature, and it is about in the earth's crust, and the content is second only to oxygen.

Chemical Reaction Equation:

si+2f2==sif4

si+4hf==sif4↑ +2h2↑

Si+2NaOH+H2O==Na2SiO3+2H2 Si+O2=SiO2 (ignition).

SIO2 + 2C = SI (Crude Silicon) +2CO High Temperature) SI (Crude Silicon) +2Cl2 = SiCl4

sicl4 +2h2=△=si + 4hcl

The Si chemical element is silicon. Silicon is an extremely common element, but it rarely occurs in nature in the form of elemental substances, but in the form of complex silicates or silica, which are widely found in rocks, gravel, and dust. Silicon is the eighth largest reserve in the universe.

In the earth's crust, it is the second most abundant element, constituting the total mass of the earth's crust, second only to oxygen (.

Uses of silicon. High-purity semiconductor: silicon is used in integrated circuits High-purity monocrystalline silicon is an important semiconductor material, which can be made into diodes, transistors, thyristors and various integrated circuits (including chips and CPUs in people's computers), and can also be made into solar photovoltaic cells, which convert radiant energy into electrical energy, in 2012, China has surpassed Europe and Japan to become the world's largest producer of solar cells.

High-temperature resistant materials: silicon can be used to make cermet composites, which inherit the respective advantages of metals and ceramics, and also make up for the shortcomings of both, with the advantages of high temperature resistance, toughness, and cutability. The first space shuttle, Columbia, relied on a shell made of silicon tiles to withstand the high temperatures caused by friction when the aircraft traveled through the dense atmosphere at high speed.

The above content refers to Encyclopedia-Silicon.