Sulfur compounds. The degree of oxidation of sulfur in compounds. Formulas for sulfur compounds

The subgroup of chalcogenes includes sulfur - this is the second of the elements that 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 is itself, its simple substance.

Sulfur and its characteristics

This element has the following position in the periodic table.

1. The sixth group, the main subgroup.
2. The third small period.
3. The atomic mass is 32,064.
4. The ordinal number is 16, protons and electrons are the same, neutrons are also 16.
5. Refers to non-metal elements.
6. The formulas read as "es", the name of the element of sulfur, Latin sulfur.

In nature, there are four stable isotopes with mass numbers 32, 33, 34 and 36. This element is the sixth most abundant 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: 1s ² 2s ² 2p ⁶ 3s ² 3p ⁴ .

The above procedure reflects only the stationary state 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 sublevel, followed by a further 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:

• -2;
• +2;
• +4;
• +6.

Of these, S ⁺² is seldom found, 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 degree of oxidation in the compound, the more pronounced oxidizing abilities the substance will possess. This is easily seen if we recall the two basic acids that form sulfur:

• H ₂ SO ₃ - sulfurous;
• H ₂ SO ₄ - sulfuric.

It is known that the latter is a much more stable, strong compound, which has a very high oxidation potential in high concentration.

Simple substance

As a simple substance, sulfur is yellow, beautiful crystals of 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 110 ^° C.

If you do not miss the intermediate moment when heating such a modification, then you can find another condition in time - plastic sulfur. 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. They are able to ignite upon contact with moisture and oxygen in the air. They differ in sufficiently high 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 contains:

• 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:

• cinnabar;
• pyrite;
• Sphalerite;
• Antimonitis;
• 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.

Physical properties

They can be described by several points.

1. In water it is insoluble, in carbon disulphide or turpentine - it dissolves well.
2. With prolonged friction accumulates a negative charge.
3. The melting point is 110 ^° C.
4. The boiling point is 190 ^° C.
5. When it reaches 300 ^° C, it passes into a liquid, easily moving.
6. Pure substance is capable of self-igniting flammable properties are very good.
7. The smell itself has practically no smell, however hydrogen compounds of sulfur emit a sharp smell of rotten eggs. Just like some gaseous binary representatives.

The physical properties of the substance in question were 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.

Chemical properties

Theme: "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 oxidizing properties with stronger reducing agents (metals, boron and others), and reducing with most non-metals.

However, in spite of such activity, only with fluorine, the interaction takes place under normal conditions. For all others, heating is required. It is possible to designate several categories of substances with which sulfur can interact:

• Metals;
• Nonmetals;
• Alkalis;
• 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 main element - sulfur. So, we can distinguish several basic types of substances on this basis:

• Compounds with a degree of oxidation -2;
• +4;
• +6.

If, on the other hand, we consider classes, and not valence, then the given element forms such molecules as:

• Acids;
• Oxides;
• Hydrogen sulfur compounds;
• Salts;
• 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:

• Carbon;
• Hydrogen;
• Phosphorus;
• Silicon;
• Arsenic;
• Boron.

In these cases, it acts as an oxidizer, since all of the listed elements are more electropositive. Consider the most important of them.

1. Carbon disulfide is CS ₂ . Transparent liquid with a characteristic pleasant aroma 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.
2. Hydrogen sulphide or hydrogen sulphide - H ₂ S. A gas that has no color and sweet taste. The smell is sharp, extremely unpleasant, like a rotten egg. Poisonous, depresses the respiratory center, since 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.
3. Metal sulphides are widely used in medicine, in sulfuric acid production, in the production of paints, in the manufacture of phosphors and other places. The general formula is Me _x S _y .

Compounds with an oxidation state of +4

The sulfur compounds 4 are predominantly an oxide and the corresponding salts and acid. All of them are quite common compounds having a definite value in industry. They can act as oxidants, but they often show restorative properties.

The formulas for a sulfur compound with an oxidation state of +4 are as follows:

• Oxide - sulfur dioxide SO ₂ ;
• Acid - sulfurous H ₂ SO ₃ ;
• Salts have the general formula Me _x (SO ₃ ) _y.

One of the most common is sulfur dioxide, or anhydride. It is a colorless substance with the smell of a burnt match. In large clusters formed during the eruption of volcanoes, it at this moment is easy to determine by smell.

It dissolves in water with the formation of an easily decomposable acid - sulphurous. Behaves like a typical acidic oxide, forms salts, which is included in the form of the SO ₃ ^2- sulfite ion. 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:

• Sulfates;
• Hydrosulphates.

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 - is a 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 CaSO ₄ · 2H ₂ O;
• Barite BaSO ₄ ;
• The mirabilite;
• Lead sulphate 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 in metallurgy, 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 way for students to learn about what sulfur is, what are its properties, what is the sulfur compound? 9th grade is the best period. This is not the very 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 taken out for study only in the 10th grade, when organic issues are considered. They also affect biology in the upper grades. After all, sulfur is a part of such organic molecules as:

• Thioalcohols (thiols);
• Proteins (tertiary structure on which disulfide bridges are formed);
• Thioaldehydes;
• Thiophenols;
• Thioethers;
• Sulfonic acids;
• Sulfoxides and others.

They are isolated in a special group of organosulfur compounds. 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 such compounds as some:

• Amino acids;
• Enzymes;
• Vitamins;
• Hormones.