Silicon (chemical element): properties, characteristics, formula. History of the discovery of silicon

Many modern technological devices and devices were created due to the unique properties of substances in nature. Humanity experimentally and carefully study the surrounding elements constantly modernizes their own inventions - this process is called technological progress. It is based on elementary, accessible to everyone things that surround us in everyday life. For example, sand: what can be surprising and unusual in it? Scientists were able to distinguish from it silicon - a chemical element, without which there would be no computer technology. The field of its application is diverse and constantly expanding. This is achieved due to the unique properties of the silicon atom, its structure and the possibility of compounds with other simple substances.

Characteristic

In a periodic system developed by DI Mendeleev, silicon (a chemical element) is denoted by the symbol Si. Refers to non-metals, is located in the main fourth group of the third period, has an atomic number of 14. Its proximity to carbon is not accidental: in many respects their properties are comparable. In nature it does not occur in pure form, since it is an active element and has strong enough bonds with oxygen. The main substance is silica, which is an oxide, and silicates (sand). In this case, silicon (its natural compounds) is one of the most common chemical elements on Earth. By mass content, it is second only to oxygen (more than 28%). The upper layer of the earth's crust contains silicon in the form of dioxide (this is quartz), various types of clays and sand. The second most common group is its silicates. At a depth of about 35 km from the surface there are layers of granite and basalt deposits, which contain siliceous compounds. The percentage of content in the Earth's core has not yet been calculated, but the closest layers of the mantle (up to 900 km) contain silicates. In the composition of sea water, the concentration of silicon is 3 mg / l, the lunar soil is 40% composed of its compounds. Space expanses, which humanity has studied to date, contain this chemical element in large quantities. For example, the spectral analysis of meteorites that were approaching the Earth at a distance accessible to researchers showed that they consist of 20% silicon. There is a probability of forming life on the basis of this element in our galaxy.

Research process

The history of the discovery of the chemical element of silicon has several stages. Many of the substances systematized by Mendeleev have been used by mankind for centuries. At the same time, the elements were in a natural form, i.e. In compounds that were not subjected to chemical treatment, and all their properties were not known to people. In the process of studying all the features of the substance, he had new uses. The properties of silicon have not been studied to the end to the end - this element, with a sufficiently broad and diverse range of applications, leaves room for new discoveries for future generations of scientists. Modern technologies will significantly accelerate this process. In the XIX century, many famous chemists tried to get silicon in its pure form. It was the first time that L. Tenar and J. Gay-Lussac succeeded in doing this, but the discovery of the element belongs to J. Berzelius, who was able not only to isolate the substance, but also to describe it. A chemist from Sweden received silicon in 1823, for this he used metallic potassium and potassium salt. The reaction occurred at the catalyst as a high temperature. The resulting simple gray-brown substance was amorphous silicon. A crystal clear element was obtained in 1855 by Saint Clair Deville. The complexity of the separation is directly related to the high strength of atomic bonds. In both cases, the chemical reaction is directed to the process of purification from impurities, while the amorphous and crystalline models have different properties.

Silicon: the pronunciation of a chemical element

The first name of the received powder - kizel - was proposed by Berzelius. In the United Kingdom and the United States, silicon is still referred to as Silicium or Silicon. The term comes from the Latin "flint" (or "stone"), and in most cases it is tied to the concept of "land" due to its wide spread in nature. Russian pronunciation of this chemical is different, it all depends on the source. It was called silica (Zakharov used this term in 1810), sicily (1824, Dvigubsky, Solovyov), silica (1825, Strakhov), and only in 1834 the Russian chemist Herman Ivanovich Hess introduced the name, which until now is used In most sources - silicon. In the periodic system of Mendeleev it is denoted by the symbol Si. How is the chemical element of silicon readable? Many scientists of English-speaking countries pronounce its name as "si" or use the word "silicone". From here comes the world-famous name of the valley, which is a research and production site for computer equipment. The Russian-speaking population calls the element silicon (from the Greek word "cliff, mountain").

Finding in nature: deposits

Whole mountain systems are composed of silicon compounds, which in its pure form does not occur, because all known minerals are dioxides or silicates (aluminosilicates). Amazing stones are used by people as ornamental materials - opals, amethysts, quartz of various types, jasper, chalcedony, agate, rock crystal, carnelian and many others. They formed due to the inclusion in the composition of silicon of various substances, which determined their density, structure, color and direction of use. The entire inorganic world can be associated with this chemical element, which in the natural environment forms strong bonds with metals and not metals (zinc, magnesium, calcium, manganese, titanium, etc.). Compared with other substances, silicon is readily available for production on a production scale: it is found in most types of ore and minerals. Therefore, actively developed deposits are tied more to affordable sources of energy than to territorial clusters of matter. Quartz and quartz sands are in all countries of the world. The largest producers and suppliers of silicon are: China, Norway, France, USA (West Virginia, Ohio, Alabama, New York), Australia, South Africa, Canada, Brazil. All manufacturers use different methods, which depend on the type of output (technical, semiconductor, high-frequency silicon). A chemical element, additionally enriched or, conversely, purified from all kinds of impurities, has individual properties, on which its further use depends. This also applies to this substance. The structure of silicon determines the scope of its application.

Usage history

Very often, because of the similarity of names, people confuse silicon and flint, but these concepts are not identical. Let's make it clear. As already mentioned, in nature, silicon is not found in its pure form, which can not be said for its compounds (the same silica). The main minerals and rocks formed by the dioxide of the substance we are considering are sand (river and quartz), quartz and quartzites, feldspars and flint. The last heard, it must be, everything, because it is given great importance in the history of the development of mankind. With this stone, the first tools of labor created by people during the Stone Age are associated. Its sharp edges, formed during chipping away from the main rock, greatly facilitated the work of ancient housewives, and the possibility of sharpening - hunters and fishermen. Flint did not possess the strength of metal products, but the failed tools were easily replaced with new ones. Its use as a flint lasted many centuries - until the invention of alternative sources.

As for modern realities, the properties of silicon allow you to use the substance for decorating rooms or creating ceramic dishes, besides having a beautiful aesthetic appearance, it has many excellent functional qualities. A separate direction of its application is associated with the invention of glass about 3000 years ago. This event made it possible to create mirrors, dishes, mosaic stained glass from compounds containing silicon. The formula of the initial substance was supplemented with the necessary components, which made it possible to impart the desired color to the product and influenced the strength of the glass. Surprising in the beauty and variety of works of art were made by man from minerals and stones containing silicon. Healing properties of this element were described by scientists of antiquity and used throughout the history of mankind. They laid out wells for drinking water, storages for storage of food, used both in everyday life and in medicine. The powder obtained as a result of grinding was applied to the wounds. Particular attention was paid to water, which was infused into dishes made of compounds containing silicon. The chemical element interacted with its composition, which made it possible to destroy a number of pathogenic bacteria and microorganisms. And this is far from being all branches where the substance considered by us is very, very much in demand. The structure of silicon determines its multifunctionality.

Properties

For a more detailed acquaintance with the characteristics of the substance, it must be considered taking into account all possible properties. The plan for the characteristic of the chemical element of silicon includes physical properties, electrophysical indices, the study of compounds, reactions and conditions of their passage, etc. Silicon in crystalline form has a dark gray with a metallic outflow of color. The face-centered cubic lattice resembles a carbon lattice (diamond), but due to the longer bond lengths it is not so strong. Plastic it makes heating up to 800 ^о С, in other cases it remains fragile. The physical properties of silicon make this substance truly unique: it is transparent to infrared radiation. The melting point is 1410 ⁰ С, the boiling point is 2600 ⁰ С, the density under normal conditions is 2330 kg / m ³ . The thermal conductivity is not constant, for different samples it is taken at an approximate value of 25 ⁰ C. The properties of the silicon atom make it possible to use it as a semiconductor. This direction of application is most in demand in the modern world. The amount of electrical conductivity is affected by the composition of silicon and the elements that are in connection with it. Thus, for increased electronic conductivity, antimony, arsenic, phosphorus, for perforated aluminum, gallium, boron, and indium are used. When creating devices with silicon as a conductor, surface treatment by a certain agent is applied, which influences the operation of the device.

The properties of silicon as an excellent conductor are widely used in modern instrument making. Especially relevant is its use in the manufacture of complex equipment (for example, modern computing devices, computers).

Silicon: characteristic of a chemical element

In most cases, silicon is tetravalent, and there are also bonds in which it can have a value of +2. Under normal conditions it is inactive, has strong compounds, at room temperature can only react with fluorine in the gaseous aggregate state. This is due to the effect of blocking the surface of the dioxide film, which is observed when interacting with surrounding oxygen or water. To stimulate the reactions, it is necessary to use a catalyst: an increase in temperature is ideal for a substance such as silicon. The chemical element interacts with oxygen at 400-500 ⁰ C, as a result, the dioxide film increases, the oxidation process proceeds. When the temperature is raised to 50 ^° C, a reaction with bromine, chlorine, iodine is observed, resulting in the formation of volatile tetrahalides. With acids, silicon does not interact, except for a mixture of hydrofluoric and nitric, with any alkali in the heated state being a solvent. Silicic acids are formed only by the decomposition of silicides, it does not enter into a reaction with hydrogen. The greatest strength and chemical passivity are distinguished by compounds with boron and carbon. High resistance to alkalis and acids has a compound with nitrogen, which occurs at temperatures above 1000 ^° C. Silicides are obtained by reaction with metals, in which case the valence, which silicon shows, depends on the additional element. The formula of a substance formed with the participation of a transition metal is resistant to acids. The structure of the silicon atom directly affects its properties and the ability to interact with other elements. The process of formation of bonds in nature and under the influence on matter (in laboratory, industrial conditions) differs significantly. The structure of silicon implies its chemical activity.

Structure

The structure of the silicon atom has its own peculiarities. The charge of the nucleus is +14, which corresponds to the ordinal number in the periodic table. The number of charged particles: protons - 14; Electrons - 14; The structure of the silicon atom has the following form: Si +14) 2) 8) 4. At the last (external) level there are 4 electrons, which determines the degree of oxidation with the sign "+" or "-". Silicon oxide has the formula SiO ₂ (valence 4+), volatile hydrogen compound - SiH ₄ (valence -4). The large volume of the silicon atom allows in some compounds to have a coordination number of 6, for example, when combined with fluorine. The molar mass is 28, the radius of the atom is 132 pm, the configuration of the electron shell is 1S ² 2S ² 2P ⁶ 3S ² 3P ² .

Application

Surface or fully alloyed silicon is used as a semiconductor in the creation of many, including high-precision instruments (for example, solar photocells, transistors, rectifiers, etc.). Super-pure silicon is used to create solar cells (energy). A single-crystal view is used to fabricate mirrors and a gas laser. Of silicon compounds, glass, ceramic tiles, dishes, porcelain, and faience are produced. The diversity of the types of goods received is difficult to describe, their exploitation takes place at the everyday level, in art and science, and in production. The resulting cement serves as a raw material for building mortars and bricks, and finishing materials. Propagation of oils, lubricants based on organosilicon compounds can significantly reduce the frictional force in the moving parts of many mechanisms. Silicides due to unique properties in the field of counteracting aggressive environments (acids, temperatures) are widely used in industry. Their electrical, nuclear and chemical indicators take into account specialists in complex industries, not the least role is played by the structure of the silicon atom.

We listed the most knowledge-intensive and advanced areas of application to date. The most common, manufactured in large volumes of technical silicon is used in a number of ways:

1. As a raw material for the production of a cleaner substance.
2. For the alloying of alloys in the metallurgical industry: the presence of silicon increases refractoriness, increases resistance to corrosion and mechanical strength (with an excess of this element, the alloy may be too brittle).
3. As a deoxidizer to remove excess oxygen from the metal.
4. Raw materials for the production of silanes (compounds of silicon with organic substances).
5. For the production of hydrogen from an alloy of silicon with iron.
6. Manufacture of solar panels.

The value of this substance is also great for the normal functioning of the human body. The structure of silicon, its properties are, in this case, decisive. In this case, the excess or lack of it leads to serious diseases.

In the human body

Medicine has long used silicon as a bactericidal and antiseptic agent. But with all the benefits of external application, this element must be constantly renewed in the human body. The normal level of its content will improve life in general. In case of its lack, more than 70 microelements and vitamins will not be absorbed by the body, which will significantly reduce the resistance to a variety of diseases. The highest percentage of silicon is observed in bones, skin, and tendons. It plays the role of a structural element that maintains strength and gives elasticity. All skeletal solid tissues are formed by its compounds. As a result of recent studies, the content of silicon in the kidneys, pancreas and connective tissues was found. The role of these organs in the functioning of the body is large enough, so reducing its content will be disastrous for many basic indicators of life support. In a day with food and water, the body should receive 1 gram of silicon - this will help to avoid possible diseases such as inflammation of the skin, softening of the bones, the formation of stones in the liver, kidneys, deterioration of eyesight, hair and nails condition, atherosclerosis. At a sufficient level of the content of this element, immunity increases, metabolic processes normalize, and the assimilation of many elements necessary for human health improves. The greatest amount of silicon - in cereals, radish, buckwheat. Significant benefit will bring silicon water. To determine the number and frequency of its use, it is better to consult a specialist.