Characteristics of sulfur. Application of sulfur. Medical sulfur

Chalcogens - a group of elements, which includes sulfur. Its chemical sign is S, the first letter of the Latin name Sulfur. The composition of a simple substance is recorded with this symbol without an index. Let's consider the basic moments concerning structure, properties, reception and application of the given element. The sulfur characteristics will be presented in the most detail.

Common signs and differences of chalcogenes

Sulfur refers to a subgroup of oxygen. This is the 16th group in the modern long-period form of the image of the periodic system (PS). The outdated version of the number and index is VIA. Names of chemical elements of the group, chemical signs:

• Oxygen (O);
• Sulfur (S);
• Selenium (Se);
• Tellurium (Te);
• Polonium (Po).

The outer electronic shell of the above elements is arranged identically. In total, it contains 6 valence electrons, which can participate in the formation of a chemical bond with other atoms. Hydrogen compounds correspond to the composition of H ₂ R, for example, H ₂ S is hydrogen sulfide. The names of chemical elements, forming with oxygen compounds of two types: sulfur, selenium and tellurium. The general formulas for the oxides of these elements are RO ₂ , RO ₃ .

Chalcogen corresponds to simple substances, which differ significantly in physical properties. The most common in the earth's crust of all the chalcogenes are oxygen and sulfur. The first element forms two gases, the second - solids. Polonium - a radioactive element - is rarely found in the earth's crust. In the group from oxygen to polonium, the nonmetallic properties decrease and the metal properties increase. For example, sulfur is a typical non-metal, and tellurium has a metallic luster and electrical conductivity.

Element number 16 of the periodic table D.I. Mendeleyev's

The relative atomic mass of sulfur is 32,064. Of the natural isotopes, the most common is ³² S (more than 95% by weight). There are smaller quantities of nuclides with an atomic mass of 33, 34 and 36. The characteristics of sulfur by position in the PS and the structure of the atom:

• The serial number is 16;
• The charge of the nucleus of the atom is +16;
• The radius of the atom is 0.104 nm;
• The ionization energy is -10.36 eV;
• Relative electronegativity is 2.6;
• The degree of oxidation in the compounds is +6, +4, +2, -2;
• Valence - II (-), II (+), IV (+), VI (+).

Sulfur is in the third period; Electrons in the atom are located at three energy levels: on the first - 2, on the second - 8, on the third - 6. All external electrons are valent. When interacting with more electronegative elements, sulfur gives up 4 or 6 electrons, acquiring typical oxidation states of +6, +4. In reactions with hydrogen and metals, the atom attracts the missing 2 electrons before filling the octet and reaching a steady state. The degree of oxidation in this case is reduced to -2.

Physical properties of rhombic and monoclinic allotropic forms

Under ordinary conditions, sulfur atoms are joined together at an angle to stable chains. They can be closed in rings, which allows us to speak about the existence of cyclic sulfur molecules. Their composition reflects the formulas S ₆ and S ₈ .

The sulfur characteristic should be supplemented with a description of the differences between allotropic modifications having different physical properties.

A rhombic or α-sulfur is the most stable crystalline form. These are bright yellow crystals consisting of S ₈ molecules. The density of rhombic sulfur is 2.07 g / cm3. Light-yellow crystals of a monoclinic form are formed by β-sulfur with a density of 1.96 g / cm3. The boiling point reaches 444.5 ° C.

Preparation of amorphous sulfur

What color is the sulfur in the plastic state? It is a dark brown mass, completely unlike a yellow powder or crystals. To obtain it, you need to melt rhombic or monoclinic sulfur. At a temperature above 110 ° C, a liquid forms, with further heating it becomes darker, at 200 ° C becomes thick and viscous. If the molten sulfur is quickly poured into cold water, it will solidify with the formation of zigzag chains whose composition reflects the formula S _n .

Solubility of sulfur

Some modifications of the substance are dissolved in carbon disulphide, benzene, toluene and liquid ammonia. If the organic solutions are slowly cooled, then needle crystals of monoclinic sulfur are formed. During evaporation of liquids, transparent lemon-yellow crystals of rhombic sulfur are isolated. They are fragile, they can easily be ground into powder. Sulfur does not dissolve in water. The crystals descend to the bottom of the vessel, and the powder can float on the surface (it is not wetted).

Chemical properties

The typical non-metallic properties of element No. 16 appear in the reactions:

• Sulfur oxidizes metals and hydrogen, is reduced to the S ^2- ion;
• When burning in air and oxygen, di- and sulfur trioxide are formed, which are acid anhydrides;
• In reaction with another more electronegative element - fluorine - sulfur also loses its electrons (oxidizes).

Free sulfur in nature

As prevalence in the earth's crust, sulfur is on the 15th place among the chemical elements. The average content of S atoms in rocks and minerals is 0.05% of the mass of the earth's crust.

What color is sulfur in nature (native)? This is a light yellow powder with a characteristic odor or yellow crystals that have a glassy sheen. Deposits in the form of placers, crystalline layers of sulfur are found in areas of ancient and modern volcanism: in Italy, Poland, Central Asia, Japan, Mexico, USA. Often, during extraction, beautiful druses and giant single crystals are found.

Hydrogen sulfide and oxides in nature

In the areas of volcanism, gaseous sulfur compounds leave the surface. The Black Sea at a depth of more than 200 m is lifeless due to the release of hydrogen sulfide H ₂ S. The formula of sulfur dioxide is bivalent - SO ₂ , trivalent - SO ₃ . The listed gaseous compounds are present in some oil, gas, and natural water deposits. Sulfur is a part of coal. It is necessary for the construction of many organic compounds. When rotting proteins of chicken eggs, hydrogen sulphide is released, so it is often said that this gas smells rotten eggs. Sulfur refers to biogenic elements, it is necessary for the growth and development of humans, animals and plants.

The importance of natural sulfides and sulphates

The sulfur characteristic will be incomplete, if not to say that the element is found not only in the form of a simple substance and oxides. The most common natural compounds are salts of hydrogen sulphide and sulfuric acids. Sulphides of copper, iron, zinc, mercury, lead are found in the minerals of chalcopyrite, pyrite, sphalerite, cinnabar and galena. Sulphates can be called sodium, calcium, barium and magnesium salts, which form minerals and rocks in nature (mirabilite, gypsum, selenite, barite, kieserite, epsomite). All these compounds find application in various branches of the economy, they are used as raw materials for industrial processing, fertilizers, building materials. The medical value of some crystalline hydrates is also great.

Receiving

The substance of yellow color in the free state is found in nature at different depths. If necessary, sulfur is smelted from the rocks, without lifting them to the surface, but by pumping to the depth of superheated water vapor and compressed air. Another method involves the sublimation of fractured rocks in special furnaces. Other methods involve dissolution with carbon disulphide or flotation.

The needs of the industry in sulfur are great, therefore, to obtain an elementary substance, its compounds are used. In sulfur sulphide and sulfides, sulfur is recovered. The degree of oxidation of the element is -2. Oxidation of sulfur is carried out, raising this value to 0. For example, according to the Leblan method, sodium sulfate is reduced by coal to a sulfide. Then calcium sulphide is obtained from it, treated with carbon dioxide and water vapor. The resulting hydrogen sulphide is oxidized with air oxygen in the presence of a catalyst: 2H ₂ S + O ₂ = 2H ₂ O + ₂ S. The determination of sulfur obtained by different methods sometimes gives low purity values. Refining or purification is carried out by distillation, rectification, treatment with acid mixtures.

Application of sulfur in modern industry

Sulfur granules are used for various production needs:

1. The production of sulfuric acid in the chemical industry.
2. Production of sulfites and sulfates.
3. Release of preparations for fertilizing plants, combating diseases and pests of agricultural crops.
4. Sulfur-containing ores at mining and chemical plants are processed to produce non-ferrous metals. The accompanying production is sulfuric acid.
5. Introduction to the composition of some grades of steels for giving special properties.
6. Due to rubber vulcanization, rubber is produced.
7. Production of matches, pyrotechnics, explosives.
8. Use for the preparation of paints, pigments, artificial fibers.
9. Bleaching of tissues.

Toxicity of sulfur and its compounds

Dusty particles that have an unpleasant smell irritate the mucous membranes of the nasal cavity and respiratory tract, eyes, skin. But the toxicity of elemental sulfur is not considered particularly high. Inhalation of hydrogen sulphide and dioxide may cause severe poisoning.

If during the firing of sulfur-containing ores at metallurgical plants, the waste gases are not captured, then they enter the atmosphere. Combining with droplets and water vapor, sulfur and nitrogen oxides give rise to so-called acid rains.

Sulfur and its compounds in agriculture

Plants absorb sulfate ions together with soil solution. Reducing the sulfur content leads to a slowdown in the metabolism of amino acids and proteins in green cells. Therefore, sulfates are used for fertilizing agricultural crops.

For disinfection of poultry houses, cellars, vegetable stores, a simple substance is burned or treated with modern sulfur-containing preparations. Sulfur oxide has antimicrobial properties, which has long been used in the production of wines, when storing vegetables and fruits. Sulfur preparations are used as pesticides for combating diseases and pests of agricultural crops (powdery mildew and spider mite).

Application in medicine

Great importance was given to the study of the healing properties of the yellow powder by the great healers of antiquity Avicenna and Paracelsus. Later it was found that a person who does not receive enough sulfur with food, weakens, has health problems (these include itching and flaking of the skin, weakening of hair and nails). The fact is that without sulfur, the synthesis of amino acids, keratin, and biochemical processes in the body is disrupted.

Medical sulfur is included in ointments for the treatment of skin diseases: acne, eczema, psoriasis, allergies, seborrhea. Baths with sulfur can relieve pain in rheumatism and gout. To better assimilate the body created water-soluble sulfur-containing drugs. It is not a yellow powder, but a fine crystalline substance of white color. With external use of this compound, it is incorporated into a cosmetic skin care product.

Gypsum has long been used in the immobilization of injured parts of the human body. Glauber's salt is prescribed as a laxative medicine. Magnesia lowers blood pressure, which is used in the treatment of hypertension.

Sulfur in history

Even in ancient times, the nonmetallic yellow matter attracted human attention. But only in 1789 the great chemist Lavoisier established that the powder and crystals found in nature consist of sulfur atoms. It was believed that the unpleasant smell arising from its burning, frightens off all evil spirits. The sulfur oxide formula, which is obtained by combustion, is SO ₂ (dioxide). It is a toxic gas, its inhalation is hazardous to health. Several cases of mass extinction of people by whole villages on the coasts, in lowlands, scientists explain by the liberation of hydrogen sulfide or sulfur dioxide from the earth or water.

The invention of black powder increased the interest in yellow crystals from the military. Many battles were won thanks to the ability of masters to combine sulfur with other substances in the process of making explosives. The most important compound - sulfuric acid - also learned to apply a very long time. In the Middle Ages, this substance was called vitriolic oil, and salts - vitriol. Copper sulfate CuSO _{4 and} iron vitriol FeSO ₄ have not lost their importance in industry and agriculture.