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Silicon Nature

Sep 21, 2017

The origin of the silicon name: silicon, from the Latin silex, which means flint (flint). In the early period of the republic of China, scholars translated this element into "si" and read it as "xi." (" si "is the foreign body of" xi "and" huo "). However, in the time and space of the time, as the pinyin scheme has not been popularized, a large number of misreading is GUI. Because of chemical element translation except China's original name, multi-use transliteration, chemical society notices this problem, then creates "silicon" word to avoid misreading. The word "silicon" is used in Taiwan

Physical properties

There are amorphous silicon and crystalline silicon. Crystalline silicon is grey, amorphous silicon is black,

2.32 2.34 g/cm3 density, melting point 1410 ℃, boiling point 2355 ℃, crystalline silicon belongs to atomic crystal. Insoluble in water, nitric acid and hydrochloric acid, soluble in hydrofluoric acid and lye. Hard and metallic luster.

Chemical property

Silicon has obvious non-metallic properties and can be dissolved in alkali - metal hydride solutions, producing (partial) silicates and hydrogen.

The silicon atom is in the fourth main family of the periodic table. Its atomic number is Z= 14, and there are 14 electrons outside the core. The electron is outside the nucleus, and it is surrounded by layers of low silicon atoms, which are called the shell structure of the electron. The first layer of the silicon atom has two electrons, and the second layer has eight electrons to reach the stable state. There are four electrons in the outermost shell that are valence electrons, which play a leading role in the electrical conductivity of silicon atoms.

Because of silicon atoms have such a structure, so there are some special properties: the outermost four valence electrons to silicon atoms in a metastable structure, these valence electrons make the silicon atoms by covalent bonds in combination with each other, because a covalent bond is strong, the silicon has high melting point and density; Chemical properties are relatively stable, and it is difficult to react with other substances (except fluoride and lye) in normal temperature. There is no obvious free electron in silicon crystal, able to conduct electricity, but the conductivity is not as high as metal, and as the temperature increases, it has a semiconductor property.

It can be used as a non-metallic role such as halogen, nitrogen, carbon and other metals such as Mg, Ca, Fe, Pt, etc. The formation of silicification. Insoluble in common inorganic acid, soluble in alkali solution, and hydrogen is released to form the corresponding alkali metal silicate solution, at the red heat temperature, and water vapor can function.

Available magnesium powder manufacturing method: the laboratory under the red heat reduction of powdered silica, with dilute acid to produce magnesium oxide and magnesium powder, reoccupy hydrofluoric acid wash not effect of silica, a quick elemental silicon. This method is not pure amorphous silicon, which is brown and black powder. Silicon is produced in an electric arc furnace to restore silica (more than 99% of SiO2 content). The reducing agent used is petroleum coke and coke. When using dc arc furnace, it can replace charcoal with petroleum coke. The ash content of petroleum coke is low (0.3% ~ 0.8%), and the high quality silicon (SiO2 is greater than 99%) can be used directly to produce high quality silicon for making silicon steel sheet. High purity semiconductor silicon at 1200 ℃ of hot silicon rods with hydrogen reduction of high purity chemical hydrogen silicone SiHCl3 or SiCl4. Ultra-pure monocrystalline silicon can be prepared by direct or regional melting method