chalcogen - a group of elements to which the sulfur.Its chemical symbol - S - the first letter of the Latin word for Sulfur.Composition simple substance is recorded by this symbol without index.Consider the main points regarding the structure, properties, production and application of the element.Characteristics of sulfur will be presented in detail as possible.
Common features and differences chalcogen
Sulphur belongs to the subgroup of oxygen.This is the 16th team in the modern long-period form the image of the periodic system (PS).Outdated version number and index - VIA.Names of groups of chemical elements, chemical signs:
- oxygen (O);
- sulfur (S);
- selenium (Se);
- tellurium (Te);
- polonium (Po).
outer electron shell of the above elements arranged in the same way.It contains all six valence electrons that can participate in the formation of chemical bonds with other atoms.Hydrogen compounds have the structure H2R, e.g., H2S - hydrogen sulfide.Chemical names of elements forming a compound with oxygen two types of sulfur, selenium and tellurium.General formulas oxides of these elements - RO2, RO3.
chalcogen match simple substances, which differ significantly in physical svostvam.The most common in the crust of all the chalcogen - oxygen and sulfur.The first element defines two gases, the second - the solids.Polonium - the radioactive element - rare in the earth's crust.In the group of oxygen to the metallic properties of polonium descending and ascending metal.For example, sulfur - typical nonmetal and tellurium has a metallic luster and electric conductivity.
element number 16 of the periodic system DIMendeleev
relative atomic mass of sulfur - 32.064.From natural 32S isotopes most prevalent (more than 95% by weight).There are smaller amounts of nuclides with atomic mass of 33, 34 and 36. Characteristics of sulfur on the situation of the MS and atomic structure:
- serial number - 16;
- charge of the nucleus of an atom is equal to 16;
- atomic radius - 0,104 nm;
- ionization energy of -10.36 eV;
- relative electronegativity - 2.6;
- oxidation state in compounds - 6, 4, 2, -2;
- valence - II (-), II (+), IV (+), VI (+).
Sera is located in the third period;the electrons in the atoms are arranged in three power levels: on the ground - 2, on the second - 8, in the third - 6 valence electrons are all external.In cooperation with more electronegative elements sulfur gives 4 or 6 electrons, acquiring typical oxidation state of +6 to +4.In reactions with hydrogen and a metal atom attracts missing 2 electrons to fill the octet and reach a steady state.The oxidation state in this case is lowered to -2.
physical properties of the orthorhombic and monoclinic allotropes
Under normal conditions, the sulfur atoms are joined together at an angle of sustainable chain.They can be closed in the ring, which suggests the existence of cyclic sulfur molecules.Their composition reflects the formula S6 and S8.
Characteristics of sulfur must be supplemented by a description of differences between allotropic modifications having different physical properties.
rhombic α-sulfur, or - the most stable crystalline form.This bright yellow crystals consisting of molecules S8.Density rhombic sulfur is 2.07 g / cm3.Light yellow crystals of the monoclinic form β-formed sulfur and a density of 1.96 g / cm3.Boiling point reaches 444,5 ° C.
Getting amorphous sulfur
Color of sulfur in a plastic state?It is dark brown mass, it is not similar to the yellow powder or crystals.To obtain it is necessary to melt the rhombic or monoclinic sulfur.At temperatures above 110 ° C, a liquid is formed, while further heating it darkens at 200 ° C becomes thick and viscous.If quickly poured molten sulfur into the cold water, it hardens to form zigzag chains whose composition reflects the formula Sn.
solubility of sulfur
Some versions of substances soluble in carbon disulfide, benzene, toluene, and liquid ammonia.If organic solutions were cooled slowly, the formation of monoclinic sulfur needles.In the evaporation of liquids stand clear lemon-yellow crystals of rhombic sulfur.They are fragile and can easily be ground into powder.The sulfur is not soluble in water.The crystals sink to the bottom of the vessel, and the powder can float on the surface (not wetted).
chemical properties
The reactions are typical metallic properties of the number 16:
- sulfur is oxidized metals, hydrogen ion is reduced to S2-;
- by combustion air and oxygen are produced di- and sulfur trioxide, which are acid anhydrides;
- reaction with other more electronegative element - fluorine - sulfur also lose their electrons (oxidation).
free sulfur in nature
As the prevalence of sulfur in the earth's crust is on the 15th place among the chemical elements.The average content of S atoms in rocks and minerals is 0.05% by weight of the crust.
Color of sulfur in nature (native)?It is light yellow powder with a characteristic odor or yellow crystals with a glassy luster.Deposits in the form of deposits, the crystalline layers of sulfur found in areas of ancient and modern volcanism in Italy, Poland, Middle East, Japan, Mexico, United States.Often the extraction of drusen is a beautiful and giant single crystals.
hydrogen sulfide and oxide in nature
In areas of volcanic activity on the surface of a gaseous sulfur compounds.Black Sea at a depth of over 200 meters is lifeless due to the release of hydrogen sulfide H2S.Formula divalent sulfur dioxide - SO2, trivalent - SO3.These gaseous compounds present in the composition of some oil, gas, natural waters.Sulfur is included in the composition of the coal.It is necessary to build many organic compounds.When rotting chicken egg is released hydrogen sulfide, so it is often said that this gas smell of rotten eggs.Sulphur belongs to the biogenic elements, it is necessary for the growth and development of humans, animals and plants.
value of natural sulphide and sulphate sulfur
features would be incomplete, if not to say that the element is found not only in the form of a simple substance and oxide.The most common natural compounds - hydrogen sulfide is salts and sulfuric acid.The sulfides of copper, iron, zinc, mercury, lead found in the composition of the minerals chalcopyrite, pyrite, sphalerite, galena, and cinnabar.Sulfate can be called the sodium, calcium, barium and magnesium salts that form in nature minerals and rocks (mirabilite, gypsum, selenite, barite, kieserite, epsomite).All of these compounds are used in various sectors of the economy, are used as raw materials for industrial processing, fertilizers, construction materials.Great medical value of some crystalline.
Preparation
yellow solid in a free state occurs naturally at different depths.If necessary, the sulfur is melted from rocks without raising them to the surface, while pumping the depth superheated steam and compressed air.Another method involves the sublimation of the crushed rock in special furnaces.Other methods involve the dissolution of carbon disulfide or flotation.
industry needs high in sulfur, so for elementary substances used his connections.The hydrogen sulfide and sulfide sulfur is in the reduced form.The oxidation state of the element is equal to -2.Sulfur oxidation is carried out by increasing the value to 0. For example, the method of LeBlanc sodium sulfate is reduced to sulfide carbon.Then it is obtained from calcium sulfide, it is treated with carbon dioxide and water vapor.The resulting hydrogen sulfide is oxidized by atmospheric oxygen in the presence of a catalyst: 2H2S + O2 = 2S + 2H2O.Determination of sulfur produced in different ways, sometimes gives low levels of purity.Refining or purification is carried out by distillation, rectification, processing the mixture of acids.
The use of sulfur in modern industry
Granular sulfur goes to different production needs:
- sulfuric acid in the chemical industry.
- production of sulfites and sulfates.
- release preparations for fertilizing plants, disease and pests.
- sulfur-containing ore in the mining and chemical plants are processed to produce non-ferrous metals.Accompanying the production is sulfuric acid.
- The introduction of some grades of steel to impart special properties.
- Thanks to rubber vulcanization of rubber is obtained.
- production of matches, fireworks and explosives.
- use for the preparation of paints, pigments, synthetic fibers.
- bleaching fabrics.
toxicity of sulfur and its compounds
Particulate possessing an unpleasant smell, irritate the mucous membranes of the nasal cavity and respiratory tract, eyes and skin.But toxicity of the elemental sulfur is considered not particularly high.Inhalation of hydrogen sulphide and silica can cause severe poisoning.
If burning of sulfur-containing ores in the steel mills exhaust gases are not trapped, they enter the atmosphere.Connecting with drops and water vapor, sulfur and nitrogen oxides give rise to so-called acid rain.
Sulfur and its compounds in agriculture
Plants absorb sulfate ions with the soil solution.Reducing the sulfur content leads to a slower metabolism of amino acids and proteins in the green cells.Therefore sulfates used for fertilizing crops.
to disinfect poultry houses, cellars, vegetable stores simple substance burned or treated with modern facilities sulfa drugs.Sulfur oxide has antimicrobial properties that have long found application in the manufacture of wine, for storage of fruits and vegetables.Preparations Sulfur used as pesticides to combat diseases and pests (powdery mildew and spider mites).
Application medicine
great importance to the study of medicinal properties of yellow powder gave great physicians of antiquity Avicenna and Paracelsus.It was later found that the person does not get enough sulfur from food weakens, experiencing health problems (which include itching and flaking of the skin, weakening of hair and nails).The fact that no sulfur is disturbed amino acid synthesis, keratin, biochemical processes in the body.
Medical sulfur incorporated into the ointment for the treatment of skin diseases: acne, eczema, psoriasis, allergies, seborrhea.Sulfur baths can ease the pain of rheumatism and gout.For better absorption by the body set up water-soluble sulfa drugs.This is not a yellow powder, a fine crystalline white solid.For external use of the compound is administered in the composition of cosmetic products for skin care.
Gypsum has long been used in the immobilization of the injured parts of the body.Glauber's salt is prescribed as a laxative medicine.Magnesium lowers blood pressure, which is used in the treatment of hypertension.
Sulfur in history
Even in ancient times nonmetallic substance yellow attracted the attention of man.But in 1789, the great chemist Lavoisier found that the powder and crystals found in nature, composed of sulfur atoms.It was believed that the unpleasant smell that occurs when it is burning, repels all evil.The formula of sulfur oxide, which is produced during combustion, - SO2 (dioxide).This toxic gas inhalation it is dangerous to health.Several cases of mass extinction of entire villages of people on the coast, in the lowlands scientists explain the allocation of land or water hydrogen sulfide or sulfur dioxide.
invention of gunpowder increased interest in the yellow crystals by the military.Many battles were won due to the ability of masters to combine sulfur with other substances in the manufacture of explosives.The most important compound - sulfuric acid - also learned how to use a very long time.In the Middle Ages this substance called oil of vitriol and salt - sulfate.Copper sulphate CuSO4 and iron sulfate FeSO4 still have not lost their importance in industry and agriculture.
