Each chemical element of the periodic system and the simple and complex substances formed by it are unique. They have unique properties, and many make an undeniably significant contribution to human life and existence as a whole. The chemical element tin is no exception.
Acquaintance of people with this metal goes back to ancient times. This chemical element has played a decisive role in the development of human civilization; to this day, the properties of tin are widely used.
Tin in history
The first mention of this metal, which, as people thought before, even some magical properties, can be found in biblical texts. Tin played a decisive role in improving the life of the Bronze Age. At that time, the most durable metal alloy possessed by man was bronze, it can be obtained if the chemical element tin is added to copper. For several centuries, everything has been made from this material, from tools and ending with jewelry.
After the discovery of the properties of iron, the tin alloy did not cease to be used, of course, it is not used on a previous scale, but bronze, as well as many of its other alloys, are actively used today by man in industry, technology and medicine, along with salts of this metal, for example, such as chloride tin, which is obtained by the interaction of tin with chlorine, this liquid boils at 112 degrees Celsius, dissolves well in water, forms crystalline hydrates and smokes in air.
The position of the element in the periodic table
The chemical element tin (the Latin name stannum is “stannum”, is written with the symbol Sn) Dmitry Ivanovich Mendeleev rightfully placed at number fifty, in the fifth period. It has a number of isotopes, the most common is the isotope 120. This metal is also in the main subgroup of the sixth group, along with carbon, silicon, germanium and flerovium. Its location predicts the amphoteric nature of the properties. Equally, tin has both acidic and basic characteristics, which will be described in more detail below.
The periodic table also shows the atomic mass of tin, which is 118.69. The electronic configuration is 5s 2 5p 2 , which in the composition of complex substances allows the metal to exhibit oxidation states +2 and +4, giving away two electrons only from the p-sublevel or four electrons from the s- and p-, completely emptying the entire external level.
Electronic characteristic of the element
According to the atomic number, the perinuclear space of the tin atom contains as many as fifty electrons, they are located at five levels, which, in turn, are split into a number of sublevels. The first two have only s- and p-sublevels, and starting from the third there is a triple splitting into s-, p-, d-.
Consider the external electronic level, since it is its structure and filling with electrons that determine the chemical activity of the atom. In an unexcited state, an element exhibits a valency equal to two; upon excitation, one electron transfers from the s-sublevel to the vacant position of the p-sublevel (it can contain three unpaired electrons to the maximum). In this case, tin exhibits a valence and oxidation state of 4, since there are no paired electrons, which means that nothing keeps them at the sublevels during chemical interaction.
Simple substance metal and its properties
The simple substance tin is a metal of silver color, belongs to the group of fusible. The metal is soft, relatively easy to deform. A number of features are inherent in such a metal as tin. A temperature below 13.2 degrees Celsius is the boundary of the transition of the metal modification of tin to powder, which is accompanied by a color change from silver-white to gray and a decrease in the density of the substance. Tin is melted at 231.9 degrees, and boils at 2270 degrees Celsius. The crystal tetragonal structure of white tin explains the characteristic crunching of a metal when it is bent and heated at the point of bending by the friction of the crystals of the material against each other. Gray tin has a cubic syngony.
The chemical properties of tin have a dual essence, it enters into both acidic and basic reactions, showing amphotericity. The metal interacts with alkalis, as well as acids, such as sulfuric and nitric, and is active in the reaction with halogens.
Tin Alloys
Why are their alloys with a certain percentage of constituents used instead of pure metals more often? The fact is that the alloy has inherent properties that the individual metal does not have, or these properties are manifested much more strongly (for example, electrical conductivity, corrosion resistance, passivation or activation of the physical and chemical characteristics of metals, if necessary, etc.). Tin (the photo shows a sample of pure metal) is part of many alloys. It can be used as an additive or basic substance.
To date, a large number of alloys of a metal such as tin is known (the price for them varies widely), we will consider the most popular and used (the application of certain alloys will be discussed in the corresponding section). In general, stannum alloys have the following characteristics: high ductility, low melting point, low hardness and strength.
Some examples of alloys
- An alloy of tin and lead with some alloying additives (antimony, copper, cadmium, zinc, silver, indium) is the so-called tin for soldering, the percentage of stannum in it should be 49-51 or 59-61 percent to achieve the best bonding properties. The strength of the connection provides the formation of tin solid solution with fastened metal surfaces.
- Garth - an alloy of tin, lead and antimony - is the basis of printing ink (which is why it is not recommended to wrap food products in newspapers, in order to avoid getting into them undesirable concentrations of these metals).
- Babbitt - an alloy of tin, lead, copper and antimony - is characterized by a low coefficient of friction, high wear resistance.
- Indium-tin alloy is a low-melting material with inherent refractoriness, corrosion resistance and considerable strength.
The most important natural compounds
Tin forms a number of natural compounds - ores. The metal forms 24 mineral compounds, the most important for industry is tin oxide - cassiterite, as well as stanin - Cu 2 FeSnS 4 . Tin is scattered in the earth's crust, and the compounds formed by it are of magnetic origin. The salts of polytannic acids and tin silicates are also used in industry.
Tin and the human body
The chemical element tin is a trace element in its quantitative content in the human body. Its main accumulation is in bone tissue, where the normal metal content contributes to its timely development and the overall functioning of the musculoskeletal system. In addition to bones, tin is concentrated in the gastrointestinal tract, lungs, kidneys and heart.
It is important to note that excessive accumulation of this metal can lead to general poisoning of the body, and a longer exposure can even lead to unfavorable gene mutations. Recently, this problem is quite relevant, since the ecological state of the environment leaves much to be desired. Tin intoxication is more likely for residents of megalopolises and areas nearby industrial zones. Most often, poisoning occurs by the accumulation of tin salts in the lungs, for example, such as tin chloride and others. At the same time, a micronutrient deficiency can provoke growth retardation, hearing loss and hair loss.
Application
Metal is commercially available at many metallurgical plants and companies. Available in the form of ingots, rods, wire, cylinders, anodes made from a pure simple substance such as tin. The price ranges from 900 to 3000 rubles per kg.
Pure tin is rarely used. Its alloys and compounds are mainly used - salts. Soldering tin is used in the case of fastening parts that are not exposed to high temperatures and strong mechanical stresses made of copper alloys, steel, copper, but are not recommended for those made of aluminum or its alloys. The properties and characteristics of tin alloys are described in the corresponding section.
Solders are used for soldering microcircuits; in this situation, alloys based on a metal such as tin are also ideally suited. The photo depicts the process of using a tin-lead alloy. With it, you can perform quite delicate work.
Due to the high resistance of tin to corrosion, it is used for the manufacture of tinned iron (tinplate) - tin cans for food. In medicine, in particular in dentistry, tin is used to perform dental fillings. House pipelines are covered with tin, bearings are made of its alloys. The contribution of this substance to electrical engineering is invaluable.
Aqueous solutions of tin salts such as fluoroborates, sulfates, and also chlorides are used as electrolytes. Tin oxide is the glaze for ceramics. By introducing various tin derivatives into plastic and synthetic materials, it seems possible to reduce their flammability and the emission of harmful fumes.