Sulfur compounds. The degree of oxidation of sulfur in compounds. Formulas for sulfur compounds
The subgroup of chalcogenes includes sulfur - this isThe second of the elements, which is capable of forming a large number of ore deposits. Sulfates, sulfides, oxides, other sulfur compounds are very widespread, important in industry and nature. Therefore, in this article we will look at what they are like, what sulfur represents itself, its simple substance.
Sulfur and its characteristics
This element has the following position in the periodic table.
- The sixth group, the main subgroup.
- The third small period.
- The atomic mass is 32,064.
- The ordinal number is 16, protons and electrons are the same, neutrons are also 16.
- Refers to non-metal elements.
- The formulas read as "es", the name of the element of sulfur, Latin sulfur.
In nature, there are four stable isotopes withmass numbers 32,33,34 and 36. This element is the sixth in prevalence in nature. Refers to biogenic elements, as it is part of important organic molecules.
The electronic structure of the atom
The sulfur compounds owe their diversity to the peculiarities of the electronic structure of the atom. It is expressed by the following configuration formula: 1s22s22p63s23p4.
The above procedure reflects only the stationarystate of the element. However, it is known that if an atom is given additional energy, then it is possible to divide the electrons in the 3p and 3s sublevels, followed by another transition to 3d, which remains free. As a result, not only the valence of the atom changes, but also all possible oxidation states. Their number significantly increases, as well as the number of different substances involving sulfur.
The degree of sulfur oxidation in compounds
There are several main options for this indicator. For sulfur it is:
Of these, S is the most common+2, the rest are dispersed everywhere. The degree of oxidation of sulfur in the compounds depends on the chemical activity and oxidizing ability of the whole substance. So, for example, compounds with -2 are sulphides. In them, the element we are considering is a typical oxidant.
The higher the oxidation state in the compound,the more pronounced oxidizing abilities will be possessed by matter. This is easily seen if we recall the two basic acids that form sulfur:
- H2SO3- sulphurous;
- H2SO4- sulfuric.
It is known that the latter is a much more stable, strong compound that has a very high oxidation capacity in high concentration.
As a simple substance, sulfur is ayellow beautiful crystals of regular regular elongated shape. Although this is only one of its forms, because there are two basic allotropic modifications of this substance. The first, monoclinic or rhombic - this is the yellow crystalline body, not capable of dissolving in water, but only in organic solvents. It is distinguished by the fragility and beautiful shape of the structure, represented in the form of a crown. The melting point is about 1100FROM.
If you do not miss an intermediate moment whenheating of such a modification, then another condition, plastic sulfur, can be detected in time. It is a rubber-like, viscous brown solution, which, with further heating or abrupt cooling, again becomes a rhombic form.
If we talk about chemically pure sulfur,obtained by multiple filtration, it is a bright yellow small crystals, brittle and completely insoluble in water. Are capable to ignite at contact to a moisture and oxygen of air. Differently high enough chemical activity.
Being in nature
In nature there are natural deposits, from which sulfur compounds are extracted and it is itself a simple substance. In addition, it is contained:
- in minerals, ores and rocks;
- in the body of animals, plants and humans, as it is part of many organic molecules;
- in natural gases, oil and coal;
- in oil shale and natural waters.
You can name a few of the richest in sulfur minerals:
- galena and others.
Most of the sulfur produced today is spent on sulfuric production. Another part is used for medical purposes, agriculture, industrial processes for the production of substances.
They can be described by several points.
- In water it is insoluble, in carbon disulphide or turpentine - it dissolves well.
- With prolonged friction accumulates a negative charge.
- The melting point is 1100FROM.
- Boiling point 1900FROM.
- At the achievement of 3000C goes into liquid, easily moving.
- The pure substance is capable of self-igniting flammable properties are very good.
- The smell itself practically does not have, however, hydrogen compounds of sulfur emit a sharp smell of rotten eggs. Just like some gaseous binary representatives.
Physical properties of the substance in questionwere known to people since antiquity. It was for its combustibility that sulfur was given such a name. In wars, suffocating and poisonous vapors were used, which are formed by the combustion of this compound, as a weapon against enemies. In addition, acids with sulfur also have always been of great industrial importance.
Subject:"Sulfur and its compounds" in the school course of chemistry takes more than one lesson. There are a lot of them. This is due to the chemical activity of this substance. It can exhibit both oxidative properties with stronger reducing agents (metals, boron and others), and regenerative with most non-metals.
However, despite such activity, only withfluorine, the reaction proceeds under ordinary conditions. For all others, heating is required. It is possible to identify several categories of substances with which sulfur can interact:
- strong oxidizing acids - sulfuric and nitric.
Sulfur compounds: varieties
Their diversity will be explained by the unequal value of the degree of oxidation of the basic element - sulfur. So, we can distinguish several basic types of substances on this basis:
- compounds with a degree of oxidation -2;
If we consider classes, rather than the valence index, then this element forms such molecules as:
- hydrogen compounds of sulfur;
- binary compounds with nonmetals (carbon disulfide, chlorides);
- organic matter.
Now consider the main of them and give examples.
Substances with an oxidation state of -2
Sulfur compounds 2 are its conformations with metals, as well as with:
In these cases, it acts as an oxidizer, since all of the listed elements are more electropositive. Consider the most important of them.
- Carbon disulfide - CS2. Transparent liquid with a characteristic pleasantaroma of ether. It is toxic, flammable and explosive. Used as a solvent, and for most types of oils, fats, non-metals, silver nitrate, resins and rubbers. It is also an important part in the production of artificial silk - viscose. In the industry it is synthesized in large quantities.
- Hydrogen sulphide or hydrogen sulphide - H2S. A gas that is colorless and sweet to taste.The smell is sharp, extremely unpleasant, like a rotten egg. Poisonous, depresses the respiratory center, because it binds copper ions. Therefore, when they are poisoned, they become suffocated and die. It is widely used in medicine, organic synthesis, sulfuric acid production, and also as an energy-efficient raw material.
- Metal sulfides are widely used in medicine, in sulphate production, in the production of paints, in the manufacture of phosphors and other places. The general formula is MexSand.
Compounds with an oxidation state of +4
The sulfur compounds 4 are predominantly an oxide andthe salts and acid corresponding to it. All of them are quite common compounds having a definite value in industry. They can also act as oxidizers, but more often they show restorative properties.
The formulas for the sulfur compound with oxidation state +4 are as follows:
- oxide - sulfur dioxide SO2;
- acid - sulphurous H2SO3;
- the salts have the general formula Mex(CO3)and.
One of the most commonsulfur dioxide, or anhydride. It is a colorless substance with the smell of a burnt match. In large clusters formed by the eruption of volcanoes, it is at this point easy to determine by smell.
It dissolves in water with the formation of easily decomposable acid - sulphurous. Behaves like a typical acidic oxide, forms salts, which is included in the form of a sulfite ion SO32-. This anhydride is the main gas that affects the pollution of the surrounding atmosphere. It affects the formation of acid rain. In the industry it is used in sulfuric acid production.
Compounds in which the oxidation state of sulfur +6
These include, first of all, sulfuric anhydride and sulfuric acid with its salts:
Since the sulfur atom in them is highly oxidized, the properties of these compounds are quite understandable. They are strong oxidants.
Sulfur oxide (VI) -sulfuric anhydride-representsa volatile colorless liquid. A characteristic feature is a strong moisture-absorbing capacity. He's smoking in the open air. When dissolved in water, it gives one of the strongest mineral acids - sulfuric acid. Its concentrated solution is a heavy oily slightly yellowish liquid. If the anhydride is dissolved in sulfuric acid, a special compound called oleum will be obtained. It is used in industry for the production of acid.
Among the salts - sulfates - great importance has such compounds as:
- gypsum CaSO4· 2H2ABOUT;
- barite BaSO4;
- the mirabilite;
- lead sulfate and others.
They find application in construction, chemical synthesis, medicine, the manufacture of optical instruments and glasses and even the food industry.
Hydrosulphates are widely used inmetallurgy, where they are used as a flux. And also they help to transfer many complex oxides to soluble sulfate forms, which is used in the respective industries.
The study of sulfur in the school course of chemistry
When is the best learning process for studentsknowledge of what sulfur is, what are its properties, what is the sulfur compound? Grade 9 is the best period. This is not the beginning, when everything is new and incomprehensible for children. This is the middle point in the study of chemical science, when the fundamentals laid down earlier will help to fully understand the topic. Therefore, for consideration of these issues, it is the second half of the graduating class that stands out. At the same time, the whole topic is divided into several blocks, in which the lesson "Sulfur compounds, 9th grade" stands apart.
This is due to their large number. The issue of sulfuric acid production in industry is also considered separately. In general, this topic is given an average of 3 hours.
But organic sulfur compounds are carried onThe study is only in the 10th grade, when questions of organic matter are considered. They also affect biology in the upper grades. After all, sulfur is part of such organic molecules as:
- thioalcohols (thiols);
- proteins (tertiary structure on which disulfide bridges are formed);
- sulfonic acids;
- sulfoxides and others.
They are isolated in a special group of organosulfur compoundsconnections. They are important not only in the biological processes of living beings, but also in industry. For example, sulfonic acids - the basis of many drugs (aspirin, sulfonamide or streptocid).
In addition, sulfur is a constant component of compounds such as some:
- amino acids;