What is the value of silicon


properties

Silicon is the most abundant electropositive element on earth. It is a semi-metal with a distinctive metallic luster and is very brittle. Silicon is usually tetravalent in its compounds, although it is sometimes divalent, and is very electropositive. In addition, pentavalent and hexavalent silicon compounds are known.

Elemental raw silicon and its semiconducting compounds are incorporated into alloys to make metals such as aluminum, magnesium, copper and other metals more resistant.
Metallurgical silicon with a purity of 98-99% is used as a raw material for the production of organic silicon and silicon resins, seals and oils. Silicon chips are used in the integrated circuits. Photovoltaic cells for direct conversion of solar energy use thin slices of simple silicon crystals. Silicon dioxide is used as a raw material to produce elemental silicon and silicon carbide. Large silicon crystals are used for piezoelectric glasses. Molten quartz sands are melted into silicon glasses, which are used in laboratories and chemical plants as well as for electrical insulation. A colloidal dispersion of silicon in water is used as a coating agent and as a component for certain enamels.

Natural silicon contains 92.2% of the isotope Si-28, 4.7% of Si-29 and 3.1% of Si-30. Apart from those persistent natural isotopes, various radioactive artificial isotopes are known. Elemental silicon has the physical properties of semi-metals, similar to those of germanium and the elements in the 4th main group. Silicon is an I-semiconductor in its purest form, although the intensity of semi-permeability is greatly increased by the addition of small amounts of impurities. In terms of its chemical properties, silicon is similar to metals.

Silicon is almost as electropositive as tin and much more positive than germanium or lead. In accordance with these metallic properties, it forms four-fold positive ions and various covalent bonds. It appears as a negative ion only in some silicides and as a positive component of oxide acids or of complex anions.

It forms various hydrides, halides (many of which contain silicon-silicon compounds) and many compounds that contain oxygen, which can be ionic or covalent in character.

Silicon is found in many forms of dioxide and in the innumerable variations of natural silica compounds.

Silicon is much more abundant than any other element (apart from oxygen) in the earth. It occupies 27.72% of the earth's solid crust while oxygen occupies only 46.6%. As the next element after silicon, aluminum makes up 8.13% of the solid earth's crust.

It is known that silicon forms compounds with 64 out of 96 possible permanent elements and can still form silicides with 18 other elements. Independent of the metallic silicides that are used in large quantities in metallurgy, it forms important compounds with hydrogen, carbon, halogens, nitrogen, oxygen and sulfur. In addition, many useful organic silicon by-products are created.

Health effects of silicon

Elemental silicon is an inert material that is believed to cause pulmonary fibrosis. However, only minor damage to the lungs of laboratory animals from intratracheal injections of silicon dust has been reported. Silicon dust has very little adverse effect on lung function and does not result in any significant organic disease or toxic effects if exposure is below the limit values. Silicon can cause chronic breathing difficulties. Crystalline silicon (silicon dioxide) poses a great danger to the respiratory organs. However, the likelihood of damage during the production and normal processing of crystalline silicon is very low. Ld 50 (oral) - 3160 mg / kg. (LD50: Life-threatening dose 50th dose of a substance that results in the death of 50% of an animal population by any type of ingestion, except inhalation) Usually expressed as milligrams or grams of substance per kilogram of animal weight).

Silicon crystal dust irritates the skin and eyes on contact. Inhalation causes inflammation of the lungs and mucous membranes. Inflammation of the eyes manifests itself as tearing and redness. Redness, itching, and rash formation are symptoms of skin inflammation.

Lung cancer is directly related to occupational exposure to quartz crystals. A cause-and-effect relationship has been proven through studies on miners, diatom earthworkers, granite workers, ceramic workers, workers in the brick kiln and other workers.

Some epidemiological studies have statistically reported the significant number of increasing deaths or cases of immunological disorders and autoimmune diseases in silicon-exposed workers. These diseases and disorders include scleroderma, rheumatoid arthritis, body lupus erythematosus, and sarcoidosis.

New epidemiological studies have found important connections between occupational exposure to crystalline silicon and occurring kidney diseases and subclinical kidney changes.

Crystalline silicon can attack the immune system and lead to microbial or fungal infections (tuberculosis) - especially in workers with silicosis.

Occupational exposure to inhaled crystalline silicone is among others. cause of bronchitis, chronic stressful lung diseases (COPD) and emphyses. Some epidemiological studies suggest that these health effects may be less common or absent in nonsmokers.

Environmental effects of silicon

There is no known damage to the environment caused by silicone or its compounds.

Silicon and water

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