Sulfur is known in nature in several polymorphic crystalline modifications, in colloidal secretions, in liquid and gaseous states. IN natural conditions stable modification is rhombic sulfur (α-sulfur). At atmospheric pressure at temperatures above 95.6 ° α-sulfur passes into monoclinic β-sulfur, upon cooling it again becomes rhombic. γ-sulfur, which also crystallizes in the monoclinic syngony, is unstable at atmospheric pressure and transforms into α-sulfur. The structure of γ-sulfur has not been studied; it is conditionally assigned to this structural group.
The article considers several polymorphic modifications of sulfur: α-sulfur, β-sulfur, γ-sulfur
α modification
The English name for the mineral α-sulfur is α-Sulphur
origin of name
The name α-sulfur was introduced by Dana (1892).
Synonyms:
Rhombic sulfur. Usually just called gray. Dayton-sulfur (Suzuki, 1915) - pseudomorphosis of α-sulfur after β-sulfur.
Formula
Chemical composition
Often, native sulfur is practically pure. Sulfur of volcanic origin often contains small amounts of As, Se, Te and traces of Ti. Sulfur from many deposits is contaminated with bitumen, clay, various sulfates and carbonates. It contains inclusions of gases and a liquid containing a mother liquor with NaCl, CaCl, Na2SO4, etc. It sometimes contains up to 5.18% Se (selenium sulfur)
Varieties
1. Volcanite- (selenium sulfur) orange-red, red-brown color.
Crystallographic characteristic
Syngony. Rhombic.
Class. Dipyramidal. Some authors believed that sulfur crystallizes into a rhombo-tetrahedral class, since sometimes it has the form of sphenoids, but this form, according to Royer, is explained by the influence of an asymmetric medium (active hydrocarbons) on crystal growth.
Crystal structure of sulfur
The structure of sulfur is molecular: 8 atoms in the lattice are included in one molecule. The sulfur molecule forms eight-dimensional rings in which the atoms alternate at two levels (along the axis of the ring). 4 S atoms of one level form a square rotated by 45° relative to another square. The planes of the squares are parallel to the c-axis. The centers of the rings are located in the rhombic cell according to the "diamond" law: at the vertices and centers of the faces of the face-centered cell and at the centers of four of the eight octants into which the unit cell is divided. In the structure of sulfur, the Hume-Rothery principle is maintained, requiring coordination 2 (= 8 - 6) for the elements of the Mendeleev group V1b. In the structure of tellurium - selenium, as well as in monoclinic sulfur, this is achieved by a spiral arrangement of atoms, in the structure of rhombic sulfur (as well as synthetic β-selenium and β-tellurium) - by their ring arrangement. The S - S distance in the ring is 2.10 A, which is exactly the same as the S - S distance in the S 2 radical of pyrite (and covelline) and a little more S-S distances between S atoms from different rings (3.3 A).
Form of being in nature
Crystal Shape
The shape of the crystals is different - dipyramidal, less often thickly tabular along with (001), disphenoidal, etc. On the faces (111), figures of natural etching are observed, which are absent on the faces (113).
Doubles
Twins at (101), (011), (110) or (111) are rare; twins at (211) are also noted.
Aggregates. Solid masses, spherical and kidney-shaped secretions, stalactites and stalagmites, powdery deposits and crystals.
Physical Properties
Optical
- The color is sulfur-yellow, straw-and honey-yellow, yellow-brown, reddish, greenish, gray from impurities; sometimes from bitumen impurities the color is brown or almost black.
- The line is colorless.
- Glitter diamond
- The tide is resinous to greasy.
- Transparency. Transparent to translucent.
Mechanical
- Hardness 1-2. Fragile.
- Density 2.05-2.08.
- Cleavage by (001), (110), (111) imperfect. Separateness according to (111).
- The fracture is conchoidal to uneven.
Chemical properties
Soluble in carbon disulfide, turpentine, kerosene.
Other properties
The electrical conductivity at ordinary temperature is almost zero. With friction sulfur electrified negatively. In ultraviolet rays, a plate 2 mm thick is opaque. At atmospheric pressure, the melting temperature 112.8°; boiling point + 444.5 °. Heat of fusion at 115° 300 cal/g-atom. Heat of vaporization at 316° 11600 cal/g-atom. At atmospheric pressure at 95.6°, α-sulfur transforms into β-sulfur with an increase in volume.
artificial receiving
Obtained by sublimation or crystallization from solution.
Diagnostic signs
Easily recognizable by its yellow color, brittleness, luster and flammability.
Associated minerals. Gypsum, anhydrite, opal, jarosite, asphalt, petroleum, ozokerite, hydrocarbon gas, hydrogen sulfide, celestine, halite, calcite, aragonite, barite, pyrite
Origin and location in nature
Native sulfur is found only in the uppermost part of the earth's crust. Formed in a variety of processes.
Animal and plant organisms play an important role in the formation of sulfur deposits, on the one hand, as accumulators of S, and on the other, as contributing to the breakdown of H 2 S and other sulfur compounds. The formation of sulfur in waters, silts, soils, swamps and in oils is associated with the activity of bacteria; in the latter, it is partly contained in the form of colloidal particles. Sulfur can be released from waters containing H 2 S under the influence of atmospheric oxygen. In coastal areas, sulfur precipitates in places when fresh water is mixed with salt water (from H 2 S sea water, under the action of oxygen dissolved in fresh water). From some natural waters, sulfur is released in the form of white turbidity (the Molochnaya river in the Kuibyshev region, etc.). From the waters of sulfur sources and from swamp waters containing H 2 S and S, sulfur precipitates in the northern regions of Russia in the winter during the process of freezing. One way or another, the main source of sulfur formation in many deposits is H 2 S, whatever its origin.
Significant accumulations of sulfur are observed in volcanic areas, in the zone of oxidation of some deposits and among sedimentary strata; deposits of the last group serve as the main sources of native sulfur mined for practical purposes. In volcanic areas, sulfur is released both during volcanic eruptions and from fumaroles, solfataras, hot springs and gas jets. Sometimes a molten mass of sulfur pours out of the crater of a volcano in the form of a stream (in Japan), and at first β- or γ-sulfur is formed, which later turns into α-sulfur with a characteristic granular structure. During volcanic eruptions, sulfur mainly arises from the action of released H 2 S on sulfur dioxide or from the oxidation of hydrogen sulfide with atmospheric oxygen; it can also sublimate with water vapor. Vapors S can be captured by gases of fumaroles, jets of carbon dioxide. The blue flame observed for the first time during the stage of volcanic eruptions represents clouds of burning sulfur (Vulcano, on the Aeolian Islands, Italy). The hydrogen sulfide stage of fumaroles and solfataras, accompanied by the formation of native sulfur, follows after the stage of isolation of fluorine and chloride compounds and precedes the stage of carbon dioxide emissions. Sulfur is released from solfataras in the form of loose tuff-like products, which are easily transported by wind and precipitation, forming secondary deposits (Cove Creek, Utah, USA). 
Sulfur. Crystals in plaster
Mineral change
In the earth's crust native sulfur easily oxidized with the formation of sulfuric acid and various sulfates; under the influence of bacteria can also produce hydrogen sulfide.
Place of Birth
Sulfur deposits of volcanic origin are usually small; they are found in Kamchatka (fumaroles), on Mount Alagez in Armenia, in Italy (solfataras of Slit Pozzuoli), in Iceland, Mexico, Japan, the USA, Java, the Aeolian Islands, etc.
The release of sulfur in hot springs is accompanied by the deposition of opal, CaCO 3 , sulfates, etc. In places, sulfur replaces limestone near hot springs, sometimes it is released in the form of the finest turbidity. Hot springs depositing sulfur are observed in volcanic areas and in areas of young tectonic faults, for example, in Russia - in the Caucasus, Central Asia, Far East, on the Kuril Islands; in the USA - in Yellowstone national park, in California; in Italy, Spain, Japan, etc.
Often native sulfur is formed in the process of supergene changes during the decomposition of sulfide minerals (pyrite, marcasite, melnikovite, galena, antimonite, etc.). Quite large accumulations have been found in the oxidation zone of pyrite deposits, for example, in the Stalinskoye deposit in the Sverdlovsk region. and in the Blyavinsky deposit of the Orenburg region; in the latter, sulfur has the appearance of a dense but brittle mass of layered texture, of various colors. In the Maykain deposit in the Pavlodar region (Kazakhstan), large accumulations of native sulfur were observed between the zone of jarosites and the zone of pyrite ores.
In small quantities, native sulfur is found in the oxidation zone of very many deposits. Sulfur is known to form in connection with coal fires during spontaneous combustion of pyrite or marcasite (powdered sulfur in a number of Ural deposits), during fires in oil shale deposits (for example, in California).
In black sea silt, sulfur is formed when it turns gray in air due to the change in the monosulfuric iron contained in it.
The largest industrial sulfur deposits are found among sedimentary rocks, mainly of Tertiary or Permian age. Their formation is associated with the reduction of sulfur sulfates, mainly gypsum, less often - anhydrite. The question of the origin of sulfur in sedimentary formations is controversial. Gypsum under the influence organic compounds, bacteria, free hydrogen, etc. is reduced first, possibly to CaS or Ca (HS) 2, which, under the action of carbon dioxide and water, turn into calcite with the release of hydrogen sulfide; the latter, when reacting with oxygen, gives sulfur. Accumulations of sulfur in sedimentary strata sometimes have a reservoir character. Often they are confined to salt domes. In these deposits, sulfur is accompanied by asphalt, oil, ozocerite, gaseous hydrocarbons, hydrogen sulfide, celestine, halite, calcite, aragonite, barite, pyrite and other minerals. Pseudomorphoses of sulfur on fibrous gypsum (selenite) are known. In Russia, there are deposits of this type in the region of the Middle Volga (Syukeyevskoe Tatarstan, Alekeeevskoe, Vodinskoe Samara region, etc.), in Turkmenistan (Gaurdak, Karakum), in the Ural-Embensky district of Kazakhstan, where a number of deposits are confined to salt domes, in Dagestan (Avar and Makhachkala groups) and in other areas.
Outside of Russia, large deposits of sulfur confined to sedimentary strata are found in Italy (Sicily, Romagna), the USA (Louisiana and Texas), Spain (near Cadiz), and other countries.
Practical application of sulfur
It is used in a number of industries: in sulfuric acid, paper-cellulose, rubber, colorful, glass, cement, match, leather, etc. Great importance sulfur has in agriculture as an insectofungicide for pest control on plantations. Grapes, tea, tobacco, cotton, beets, etc. In the form of sulfur dioxide, it is used in refrigeration, is used for bleaching fabrics, for mordant in dyeing and as a disinfectant.
Physical research methods
Differential thermal analysis
Main lines on radiographs:
ancient methods. Melts easily under a blowpipe. Burns with a bluish flame releasing SO 2 . In a closed tube it gives a yellow crystalline sublimation or reddish-brown droplets, light yellow upon cooling.
Crystal optical properties in thin preparations (sections)
Biaxial (+). Density of optical axes (010); Ng - c, Nm = b, Np = a. Refractive index according to Schrauf.
Sulfur - S. The most stable α-modification of sulfur at room temperature is usually called rhombic sulfur or simply sulfur.
Chemical composition . In a number of cases, chemically pure sulfur is established, but it is usually contaminated with foreign mechanical impurities: clay or organic matter, oil droplets, gases, etc. also Te, sometimes As, and exceptionally Tl.
Syngony rhombic. Crystal structure. According to X-ray studies, rhombic sulfur has a rare for inorganic compounds molecular, and, moreover, very complex, lattice. In the crystal structure, each sulfur atom has spheres on both sides that intersect with the spheres of neighboring atoms, and the chains consisting of 8 atoms are closed.
Hence the sulfur molecule S 8 . The unit cell is composed of 16 such electrically neutral molecules (rings), very weakly connected to each other by a van der Waals bond. Crystal Shape. Crystals often have a pyramidal or truncated pyramidal appearance. Aggregates. Often found in solid, sometimes earthy masses. Occasionally, sinter kidney-shaped forms and raids are observed (in areas of volcanic eruptions).
Color. In α-sulfur, various shades of yellow are observed: straw yellow, honey yellow, yellowish gray, brown and black (from carbonaceous impurities). Features almost does not give, the powder is slightly yellowish. Shine diamond on the edges, bold in the break. Shines through in crystals. Hardness 1-2. Fragile. Cleavage imperfect. Specific gravity 2,05-2,08. Other properties. Electrical conductivity and thermal conductivity are very weak (good insulator). When rubbed, it is charged with negative electricity. It cracks from the warmth of the hand.
Diagnostic signs. Characteristic color, low hardness, brittleness, oily sheen in the fracture of crystals and fusibility. P. p. tr. and from a match easily melts (at 112.8 ° C) and ignites with a blue flame with the release of a characteristic smell of SO 2.
Native sulfur is the only mineral among the considered in the class of native elements that has the molecular structure of a substance. S is characterized by very special properties. The presence of electrically neutral S 8 molecules in the lattice as structural units explains such properties as poor electrical conductivity, low thermal conductivity, and weak bonding between molecules.
Origin. Native sulfur is found exclusively in the uppermost part of the earth's crust and on its surface. Formed in various ways:
During volcanic eruptions, settling in the form of sublimates on the walls of craters, in rock cracks, sometimes pouring out in liquid form with hot water in the form of streams (Japan). Occurs as a result of incomplete oxidation of hydrogen sulfide H 2 S in solfatars or as a reaction product of H 2 S with sulfur dioxide: 2H 2 S + 20 = 2H 2 O + 2S; H 2 S + SO 2 \u003d H 2 O + O + 2S;
Solfatars(Italian, singular solfatara, from solfo - sulfur), jets of sulfur dioxide and hydrogen sulfide mixed with water vapor, carbon dioxide and other gases released from channels and cracks on the walls and bottom of the crater, on the slopes of volcanoes.
During the decomposition of sulfur compounds of metals, mainly pyrite, in the lower parts of the oxidation zone of ore deposits. Usually heavily contaminated with various mechanical impurities;
During the decomposition of gypsum-bearing sedimentary strata. Paragenesis of native sulfur with gypsum is often observed, in the corroded areas of which it is formed in the form of crystalline and powdery masses;
Sedimentary (biochemical) way in sedimentary rocks, represented by layers containing gypsum, solid and liquid bitumen (asphalt, oil), etc. This type of deposits is widespread in the globe and is of great industrial importance. The origin of sulfur is biochemically associated with the vital activity of anaerobic bacteria, resulting in the formation of hydrogen sulfide, the incomplete oxidation of which leads to the precipitation of sulfur.
Application. The main amount of sulfur is spent on the production of sulfuric acid, which is used in many industries; then in agriculture (for pest control); in rubber production (rubber vulcanization process); in the manufacture of matches, fireworks, paints, etc.
Diamond
Diamond - C. The name comes from the Greek word "adamas" - irresistible (obviously, it means the highest hardness and resistance to physical and chemical agents). Proper name of the sample - "Gornyak"
Varieties:
-board- irregularly shaped splices and spherical radiant aggregates;
-carbonado- fine-grained porous aggregates, painted with amorphous graphite and foreign impurities in a brownish-black color.
Chemical composition. Colorless varieties are composed of pure carbon. Colored and opaque varieties in the fireproof residue, sometimes reaching several percent, detect SiO 2, MgO, CaO, FeO, Fe 2 O 3, A1 2 O 3, TiO 2, etc. Graphite and some other minerals are often observed in the form of inclusions in diamonds .
The crystal lattice of diamond. A - image of the centers of atoms; B - the same lattice in the form of tetrahedra, the vertices and centers of which are the centers of carbon atoms
Syngony cubic. Crystal Shape octahedral, less common dodecahedral, rarely cubic and occasionally tetrahedral. Crystal faces are often represented by convex and uneven, sometimes corroded surfaces. Intergrowth twins are observed. The sizes of individual crystals vary from the smallest to very large, weighing several hundred and even thousands of carats (metric carat = 0.2 g). The largest crystals weighed (in carats): "Collinan" - 3025, "Excelsior" - 969.5, "Victoria" - 457, "Orlov" - 199.6.
Color. Colorless water-transparent or colored in blue, blue, yellow, brown and black. Shine strong diamond. Hardness 10. Absolute hardness is 1000 times higher than the hardness of quartz and 150 times that of corundum. fragile. Cleavage average. Density 3,47-3,56. Electrical conductivity weak.
Diagnostic signs . Diamond is the only mineral in its exceptional hardness. A strong diamond brilliance and often curved crystal faces are also characteristic. Small grains in concentrates are easily recognized by luminescence, which is sharply manifested in ultraviolet rays. Luminescence colors are usually bluish-blue, sometimes green.
Origin. Primary deposits are genetically related to ultramafic deep igneous rocks: peridotites, kimberlites etc. In these rocks, diamond crystallization obviously occurs at great depths under conditions of high temperatures and pressure. Judging by the forms and conditions of occurrence, diamond was one of the first to crystallize in magmas. It is not clear whether the diamond crystallized from the carbon of the magma itself or from carbon assimilated from the surrounding rocks. In associations with diamond, there are: graphite, olivine - (Mg, Fe) 2 SiO 4, chrome spinels - (Fe, Mg) (Cr, Al, Fe) 2 O 4, magnetite - FeFe 2 O 4, hematite - Fe 2 O 3 and etc.
Placer deposits of diamond, stable in exogenous conditions, are formed due to the destruction and erosion of diamond-bearing rocks.
Kimberlite(from the name of the city of Kimberley in South Africa), an igneous ultrabasic brecciated rock of an effusive appearance, performing kimberlite pipes explosion.
Kimberlite pipe - a vertical or near-vertical geological body formed by the breakthrough of gases through the earth's crust. The kimberlite pipe is filled with kimberlite.
Application. Perfectly transparent diamonds are used in jewelry as gems(diamonds). For technical purposes, small diamonds are used, as well as bead and carbonado. These varieties are used in metalworking, stoneworking, abrasive and other industries.
Graphite
Graphite - S. The name comes from the Greek word "grafo" - I write. Varieties:
Graphite - cryptocrystalline difference;
Shungite is an amorphous variety formed as a result of natural coking of coals.
Chemical composition graphite is rarely pure. In significant quantities (up to 10-20%), ash is often present, consisting of various components (SiO 2, Al 2 O 3, FeO, MgO, CaO, P 2 O 5 , CuO, etc.), sometimes water, bitumen and gases (up to 2%).
Syngony hexagonal. Crystal structure in comparison with diamond is shown in the figure. Differences physical properties diamond and graphite are due to the difference in the structure of the crystal lattices of these minerals. Carbon ions in graphite lie in sheets represented by flat hexagonal grids.
The location of the centers of atoms in diamond (A) and in graphite (B)
Crystal Shape. Well-formed crystals are extremely rare. They look like hexagonal plates or tablets, sometimes with triangular strokes on the edge. Aggregates often finely scaly. Rough or fibrous masses are less common. Color iron-black to steel-gray graphite. trait black shiny. Shine strong metallic; cryptocrystalline aggregates matte. In the thinnest leaves, it is translucent in gray. Hardness 1. Flexible in thin sheets. Fat to the touch. Smudges paper and fingers. Cleavage perfect. Specific gravity 2.09-2.23 (varies depending on the degree of dispersion and the presence of the finest pores), for shungite 1.84-1.98. Other properties. It has a high electrical conductivity, which is due to the very dense packing of atoms in the sheets.
Diagnostic signs . Easily recognizable by color, low hardness and oiliness to the touch. It differs from similar molybdenite (MoS 2) by its darker iron-black color and weaker luster.
P. p. tr. does not melt. When heated in a jet of oxygen, it burns more difficult than diamond. It evaporates without melting, only in the flame of a voltaic arc. Does not dissolve in acids. The powder mixed with KNO 3 gives a flash when heated.
Origin. In nature, graphite is formed during reduction processes at high temperatures.
Metamorphic deposits of graphite are widespread, which arose due to coal or bituminous deposits under conditions of regional metamorphism or under the influence of magma intrusions.
It is sometimes found among igneous rocks of various compositions. The source of carbon in many cases is host carbonaceous rocks.
Cases of finds of graphite in pegmatites are known. There are deposits at the contacts of limestone with igneous rocks in the provinces of Ontario and Quebec in Canada, as well as vein deposits of coarse graphite, for example, on about. Ceylon.
Application. Graphite is used for the most various kinds production: for the manufacture of graphite crucibles, in foundry; production of pencils; electrodes; for lubrication of rubbing parts; in the paint industry, etc.
Group of "semimetals"
This group, in addition to arsenic, includes antimony and bismuth, i.e., elements of large periods of group V of the periodic table. All of them under natural conditions, although rare, are observed in the native state, crystallizing in one (trigonal) syngony and forming the same type crystal lattices. Despite this, the elements of the semimetal group do not occur together and do not give in nature either solid solutions or definite compounds. The exceptions are arsenic and antimony, which at high temperatures form solid solutions in all proportions, and at low temperatures - only a stable intermetallic compound AsSb (alemontite).
Intermetallic compounds- chemical compounds of metals with each other.
sulfur crystal
Native sulfur(Sulfur) is a beautiful light yellow, lemon yellow, deep yellow crystals, which will decorate any collection of minerals with their sunny color. Aggregates of a brownish color are encountered; this coloration is imparted by an admixture of organic matter. Sulfur crystals can be a fraction of millimeters in size, but they can also reach quite large sizes - up to tens of centimeters.
lemon yellow sulfur crystals
physical properties. Sulfur crystals have a monoclinic or rhombic syngony, the appearance of crystals is a combination of a cube and a rhombus. The crystals have a glassy shine. Hardness of this mineral is small - 1-2 units on the ten-point Mohs scale. Density sulfur crystals is 2.05 - 2.08 grams per cubic centimeter. The crystals are brittle and break easily on impact.
Sulfur crystals have low electrical conductivity and can be used as an electrical insulator. This mineral conducts heat poorly and is an excellent thermal insulator.
Native sulfur may contain, selenium, astatine And tellurium as an isomorphic impurity. When rubbed, this mineral is charged static electricity and can attract light objects, such as small pieces of paper.
Sulfur can be melted by heating it to a temperature of 115.2 degrees Celsius; when exposed to high temperatures, this mineral actively oxidizes and burns. At the same time, it highlights sulfuric anhydride SO3- gas with a suffocating odor.
Alchemists used native sulfur in their experiments, and this occupation among the population of European countries of that time was equal to witchcraft. In the Middle Ages and the Renaissance, the Inquisition organized a real hunt for witches and magicians. Therefore, the smell of burning sulfur has become associated with evil spirits and the devil.
Islets of sulfur, Dallol volcano, Ethiopia
Sulfur formed during the weathering of sulfide deposits of metals.
In the vicinity of some damped (or cooled down) volcanoes, solutions saturated with metal sulfide ions come to the earth's surface. During their precipitation, native sulfur is also formed ( volcanic).
This mineral can also be formed during the decomposition of some salts. So, native sulfur is formed during the oxidation and decomposition of the mineral gypsum(CaSO4 2H2O) . There are such deposits on the southern and northern coasts of Italy.
Sulfur deposits are actively developed both in Russia (the Volga region) and abroad in the United States (in Texas and Louisiana). It is used to produce sulfuric acid.
There are deposits of volcanic sulfur in Japan and Ethiopia. But in these countries, this mineral is not being mined.
Deposits of volcanic sulfur occupy large areas, while yellow, orange, red layers and streams form the most beautiful fantastic landscapes.
A volcanic eruption on Io, the satellite of Saturn (photo by the Voyager spacecraft). The surface of the planet is covered with a layer of sulfur.
Sulfur is a common mineral, both on Earth and on other planets. For example, Saturn's moon And about is a small planet (comparable in volume to the Moon), with a molten core. Volcanoes often erupt on Io; when they cool, a lot of elemental (native) sulfur is released. This mineral makes the surface of the planet look like an egg yolk.
Rocks that make up the crust Venus- mostly gray basalts. But on this planet there are many areas in which volcanoes are active. According to the scan of this planet spacecraft, the surface in these areas is also covered with a layer of native sulfur.
Extraction of native sulfur. USA, Texas.
The crystals of this bright yellow mineral are very beautiful, but the collector should be aware that they are fragile and afraid of exposure to high temperatures.
Chalcogens are a group of elements to which sulfur belongs. Its chemical symbol is S, the first letter of the Latin name Sulfur. The composition of a simple substance is written using this symbol without an index. Consider the main points regarding the structure, properties, production and use of this element. The characterization of sulfur will be presented in as much detail as possible.
Common features and differences of chalcogens
Sulfur belongs to the oxygen subgroup. This is the 16th group in the modern long period image form. periodic system(PS). An obsolete version of the number and index is VIA. Titles chemical elements groups, chemical signs:
- oxygen (O);
- sulfur (S);
- selenium (Se);
- tellurium (Te);
- polonium (Po).
The outer electron shell of the above elements has the same structure. In total it contains 6 who can participate in education chemical bond with other atoms. Hydrogen compounds correspond to the composition H 2 R, for example, H 2 S is hydrogen sulfide. The names of the chemical elements that form two types of compounds with oxygen: sulfur, selenium and tellurium. General formulas oxides of these elements - RO 2, RO 3.
Chalcogens correspond to simple substances that differ significantly in physical properties. The most common chalcogens in the earth's crust 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, non-metallic properties decrease and metallic properties increase. For example, sulfur is a typical non-metal, while tellurium has a metallic luster and electrical conductivity.
Element No. 16 of the D.I. Mendeleev
The relative atomic mass of sulfur is 32.064. Of the natural isotopes, 32 S is the most common (more than 95% by weight). Nuclides with atomic masses of 33, 34 and 36 are found in smaller quantities. Characteristics of sulfur by position in PS and atomic structure:
- serial number - 16;
- the charge of the nucleus of an atom is +16;
- atomic radius - 0.104 nm;
- ionization energy -10.36 eV;
- relative electronegativity - 2.6;
- oxidation state in compounds - +6, +4, +2, -2;
- valency - II (-), II (+), IV (+), VI (+).
Sulfur is in the third period; electrons in an atom are located on three energy levels: on the first - 2, on the second - 8, on the third - 6. All external electrons are valence. 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 until the octet is filled and a steady state is reached. in this case it drops to -2.
Physical properties of rhombic and monoclinic allotropic forms
Under normal conditions, sulfur atoms are connected to each other at an angle into stable chains. They can be closed in rings, which allows us to speak about the existence of cyclic sulfur molecules. Their composition reflect the formulas S 6 and S 8 .
The characterization of sulfur should be supplemented by a description of the differences between allotropic modifications with different physical properties.
Rhombic or α-sulfur is the most stable crystalline form. These are bright yellow crystals composed of S 8 molecules. The density of rhombic sulfur is 2.07 g/cm3. Light yellow monoclinic crystals are formed by β-sulfur with a density of 1.96 g/cm3. The boiling point reaches 444.5°C.
Obtaining amorphous sulfur
What color is sulfur in the plastic state? It is a dark brown mass, completely different from yellow powder or crystals. To obtain it, you need to melt rhombic or monoclinic sulfur. At temperatures above 110°C, a liquid is formed, with further heating it darkens, at 200°C it becomes thick and viscous. If you quickly pour molten sulfur into cold water, then it will solidify with the formation of zigzag chains, the composition of which is reflected by the formula S n.
Solubility of sulfur
Some modifications in carbon disulfide, benzene, toluene and liquid ammonia. If organic solutions are cooled slowly, needle-like crystals of monoclinic sulfur are formed. When liquids evaporate, transparent lemon-yellow crystals of rhombic sulfur are released. They are brittle and can be easily ground into powder. Sulfur does not dissolve 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 show the typical non-metallic properties of element No. 16:
- sulfur oxidizes metals and hydrogen, is reduced to the S 2- ion;
- when burned in air and oxygen, di- and sulfur trioxide are formed, which are acid anhydrides;
- in a reaction with another more electronegative element - fluorine - sulfur also loses its electrons (is oxidized).
Free sulfur in nature
In terms of prevalence in the earth's crust, sulfur is in 15th place among the chemical elements. The average content of S atoms in is 0.05% of the mass of the earth's crust.
What color is sulfur in nature (native)? It is a light yellow powder with a characteristic odor or yellow crystals with a glassy luster. 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, and the USA. Often, when mining, beautiful druze and giant single crystals are found.
Hydrogen sulfide and oxides in nature
In areas of volcanism, gaseous sulfur compounds come to the surface. The Black Sea at a depth of over 200 m is lifeless due to the release of hydrogen sulfide H 2 S. The formula of sulfur oxide is bivalent - SO 2, trivalent - SO 3. The listed gaseous compounds are present in some oil, gas, and natural water deposits. Sulfur is part of coal. It is necessary for the construction of many organic compounds. When egg whites rot, hydrogen sulfide is released, which is why it is often said that this gas has the smell of rotten eggs. Sulfur is a biogenic element, it is necessary for the growth and development of humans, animals and plants.
Importance of natural sulfides and sulfates
The characterization of sulfur will be incomplete, if not to say that the element occurs not only in the form of a simple substance and oxides. The most common natural compounds are salts of hydrosulfide and sulfuric acids. Sulfides of copper, iron, zinc, mercury, lead are found in the minerals sphalerite, cinnabar and galena. Sulfates include sodium, calcium, barium and magnesium salts, which form minerals and rocks in nature (mirabilite, gypsum, selenite, barite, kieserite, epsomite). All these compounds are used in various sectors of the economy, used as raw materials for industrial processing, fertilizers, building materials. Veliko medical significance some crystalline hydrates.
Receipt
A yellow substance in a free state occurs in nature at different depths. If necessary, sulfur is smelted from rocks, not by raising them to the surface, but by forcing superheated rocks to a depth. Another method is associated with sublimation from crushed rocks in special furnaces. Other methods involve dissolution with carbon disulfide or flotation.
The needs of industry for sulfur are great, therefore, its compounds are used to obtain elemental matter. In hydrogen sulfide and sulfides, sulfur is in reduced form. The oxidation state of the element is -2. Sulfur is oxidized, increasing this value to 0. For example, according to the Leblanc method, sodium sulfate is reduced with coal to sulfide. Then calcium sulfide is obtained from it, treated with carbon dioxide and water vapor. The resulting hydrogen sulfide is oxidized with atmospheric oxygen in the presence of a catalyst: 2H 2 S + O 2 = 2H 2 O + 2S. The determination of sulfur obtained by various methods sometimes gives low purity values. Refining or purification is carried out by distillation, rectification, treatment with mixtures of acids.
The use of sulfur in modern industry
Sulfur granulated is used for various production needs:
- Obtaining sulfuric acid in the chemical industry.
- Production of sulfites and sulfates.
- Production of preparations for plant nutrition, control of diseases and pests of agricultural crops.
- Sulfur-containing ores are processed at mining and chemical plants to obtain non-ferrous metals. Accompanying production is sulfuric acid.
- Introduction to the composition of some grades of steels to impart special properties.
- Thanks get rubber.
- Manufacture of matches, pyrotechnics, explosives.
- Use for the preparation of paints, pigments, artificial fibers.
- Bleaching fabrics.
Toxicity of sulfur and its compounds
Dust-like particles with an unpleasant odor 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 sulfide and dioxide can cause severe poisoning.
If, during the roasting of sulfur-containing ores at metallurgical plants, exhaust gases are not captured, then they enter the atmosphere. Combining with drops and water vapor, sulfur and nitrogen oxides give rise to the so-called acid rain.
Sulfur and its compounds in agriculture
Plants absorb sulfate ions along with the soil solution. A decrease in sulfur content leads to a slowdown in the metabolism of amino acids and proteins in green cells. Therefore, sulfates are used for fertilizing crops.
To disinfect poultry houses, basements, vegetable stores, a simple substance is burned or the premises are treated with modern sulfur-containing preparations. Sulfur oxide has antimicrobial properties, which has long been used in the production of wines, in the storage of vegetables and fruits. Sulfur preparations are used as pesticides to control diseases and pests of crops (powdery mildew and spider mites).
Application in medicine
The great healers of antiquity Avicenna and Paracelsus attached great importance to the study of the medicinal properties of yellow powder. Later it was found that a person who does not receive enough sulfur with food becomes weaker, experiences 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. Sulfur baths can relieve the pain of rheumatism and gout. For better absorption by the body, water-soluble sulfur-containing preparations have been created. This is not a yellow powder, but a white crystalline substance. When used externally, this compound is incorporated into a skin care cosmetic.
Gypsum has long been used in the immobilization of injured parts of the human body. prescribed as a laxative. Magnesia lowers blood pressure, which is used in the treatment of hypertension.
Sulfur in history
Even in ancient times, a non-metallic yellow substance attracted the attention of a person. But it wasn't until 1789 that the great chemist Lavoisier established that powders and crystals found in nature were composed of sulfur atoms. It was believed that the unpleasant smell that occurs when it is burned, repels all evil spirits. The formula for sulfur oxide, which is obtained during combustion, is SO 2 (dioxide). It is a toxic gas and is hazardous to health if inhaled. Several cases of mass extinction of people by entire villages on the coasts, in the lowlands, scientists explain the release of hydrogen sulfide or sulfur dioxide from the earth or water.
The invention of black powder increased military interest in yellow crystals. Many battles have been won thanks to the ability of craftsmen to combine sulfur with other substances during the manufacturing process. The most important compound is sulfuric acid- also learned to apply a very long time ago. In the Middle Ages, this substance was called vitriol oil, and salts were called vitriol. blue vitriol CuSO 4 and ferrous sulfate FeSO 4 still have not lost their importance in industry and agriculture.
Sulfur (mineral) - often found in native form, forming dense or earthy masses or crystalline aggregates in the form of crystalline drusen, films and deposits. There are also well-formed crystals reaching considerable sizes. Crystals of native S. belong to the rhombic system (rhombic bipyramid class) and have a pyramidal habit, see fig. No. 1 and 2. Sometimes, due to the uneven development of the planes of the bipyramid, a sphenoid form of crystals is obtained. The most common forms found on S. crystals: the main rhombic bipyramid (111) P, the axes of which are related A:b:With= 0.8138:1:1.9076; in addition: (113)S; (011)n and (001)s. Crystals sometimes coalesce with each other in a twin position. When split, it reveals a characteristic conchoidal fracture. S.'s hardness is insignificant, 1.5-2.5 (on the Mohs scale). Specific gravity 1.9-2.1. The color of native S. is different (from impurities of selenium, arsenic sulfide, organic matter): honey yellow, sulfur yellow, gray and brown. Luster is greasy, approaching diamond. S. is distinguished by strong birefringence, which in the case of a transparent crystal can be observed (as in Icelandic spar) directly, without any instruments. optically negative. The plane of the optical axes lies in the brachydiagonal section. optical angle axles 2 r= 69° 40′. For other properties of S. - see the chemical part of the article. Native S. is formed in nature in various ways. The largest quantities occur by water from sources and in general from waters circulating in the bowels of the earth's crust containing hydrogen sulfide. The latter, when exposed to atmospheric oxygen, is oxidized, forming water and releasing C. Similar sources are formed where there are deposits of gypsum and organic matter. Due to a number of chemical transformations from gypsum, under the action of organic substances and water, hydrogen sulfide is formed, and from the latter - S. The co-occurrence of gypsum, calcareous spar, sulfur sources, S. and organic substances is explained by a similar origin. Sometimes native S. closely adjoins and even takes root in large gypsum crystals. S. for the most part is in the form of veins, nests, zhevlaks in clays, marls and gypsum. These are the most famous deposits of Sicily, Aragon, Croatia, Dagestan, Poland and the Kazan province. The second method of S.'s formation is volcanic. It is deposited along the walls of the crater of volcanoes either as a result of direct sublimation, or as a result of the interaction of hydrogen sulfide and sulfur dioxide, the presence of which is very common in the products of volcanic activity. S.'s allocation is explained by the equation: 2H 2 S + SO 2 \u003d 2H 2 O + 3S. Finally, apparently, sulfur is also formed in nature in a third way: sulfur compounds of metals during oxidation can release free sulfur. This can explain the joint presence of the latter, for example, with sulfur pyrite (Soymonovskoye deposit in the Urals, Rio Tinto in Spain) . On the amount of S. produced annually and its application -
