The subgroup of chalcogens includes sulfur - this is the second of the elements that can form a large number of ore deposits. Sulfates, sulfides, oxides and other sulfur compounds are very widespread, important in industry and nature. Therefore, in this article we will consider what they are, what sulfur itself is, its simple substance.
Sulfur and its characteristics
This element has the following position in the Periodic Table.
- Sixth group, main subgroup.
- Third small period.
- Atomic mass - 32, 064.
- Ordinal number - 16, the same number of protons and electrons, neutrons also 16.
- Refers to non-metal elements.
- In formulas it is read as "es", the name of the element sulfur, Latin sulfur.
There are four stable isotopes in nature 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 organicmolecules.
Electronic structure of the atom
Sulfur compounds owe their diversity to the peculiarities of the electronic structure of the atom. It is expressed by the following configuration formula: 1s22s22p63s2 3p4.
The given order reflects only the stationary state of the element. However, it is known that if additional energy is imparted to an atom, then electrons can be paired at the 3p and 3s sublevels, followed by another transition to 3d, which remains free. As a result, not only the valency of the atom changes, but also all possible oxidation states. Their number is increasing significantly, as well as the number of various substances with the participation of sulfur.
Oxidation states of sulfur in compounds
There are several main variants of this indicator. For sulfur it is:
- -2;
- +2;
- +4;
- +6.
Of these, S+2 is the most rare, the rest are scattered everywhere. The chemical activity and oxidizing ability of the entire substance depends on the degree of oxidation of sulfur in compounds. So, for example, compounds with -2 are sulfides. In them, the element we are considering is a typical oxidizing agent.
The higher the value of the oxidation state in the compound, the more pronounced the oxidizing ability of the substance will be. This is easy to verify if we recall the two main acids that sulfur forms:
- H2SO3 - sulphurous;
- H2SO4 - sulfuric.
It is known thatthe latter is a much more stable, strong compound, with a very strong oxidizing ability in high concentration.
Simple substance
As a simple substance, sulfur is yellow beautiful crystals of even, regular, elongated shape. Although this is only one of its forms, because there are two main allotropic modifications of this substance. The first, monoclinic or rhombic, is a yellow crystalline body that cannot dissolve in water, but only in organic solvents. Differs in fragility and a beautiful form of the structure presented in the form of a crown. Melting point - about 1100C.
If you do not miss the intermediate moment when heating such a modification, then you can detect another state in time - plastic sulfur. It is a rubbery brown viscous solution, which, upon further heating or rapid cooling, again turns into a rhombic shape.
If we talk about chemically pure sulfur obtained by repeated filtration, then it is a bright yellow small crystals, fragile and completely insoluble in water. Able to ignite on contact with moisture and oxygen in the air. Differ in rather high chemical activity.
Being in nature
In nature, there are natural deposits from which sulfur compounds are extracted and sulfur itself as a simple substance. In addition, shecontains:
- in minerals, ores and rocks;
- in the body of animals, plants and humans, as it is part of many organic molecules;
- in natural gas, oil and coal;
- in oil shale and natural waters.
Some of the richest minerals in sulfur can be named:
- cinnabar;
- pyrite;
- sphalerite;
- antimonite;
- galena and others.
Most of the sulfur produced today goes to sulfate production. Another part is used for medical purposes, agriculture, industrial processes for the production of substances.
Physical properties
They can be described with several points.
- Insoluble in water, soluble in carbon disulfide or turpentine.
- With prolonged friction, accumulates a negative charge.
- Melting point is 110 0C.
- Boiling Point 190 0C.
- When it reaches 300 0C turns into liquid, easily mobile.
- Pure substance can ignite spontaneously combustible properties are very good.
- By itself, it has practically no smell, however, hydrogen sulfur compounds emit a sharp smell of rotten eggs. As well as some gaseous binary representatives.
The physical properties of the substance in question have been known to people since antiquity. It is for its combustibility that sulfur got its name. In wars, asphyxiating and poisonous fumes were used, which are formed during the combustion of this compound, asweapons against enemies. In addition, acids containing sulfur have also always been of great industrial importance.
Chemical properties
Theme: "Sulfur and its compounds" in the school chemistry course takes not one lesson, but several. After all, 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 properties with most non-metals.
However, despite such activity, only interaction with fluorine occurs under normal conditions. All others require heating. There are several categories of substances with which sulfur can interact:
- metals;
- non-metals;
- alkali;
- strong oxidizing acids - sulfuric and nitric.
Sulfur compounds: varieties
Their diversity will be explained by the unequal value of the oxidation state of the main element - sulfur. So, we can distinguish several main types of substances on this basis:
- compounds with oxidation state -2;
- +4;
- +6.
If we consider classes, and not the valency index, then this element forms molecules such as:
- acids;
- oxides;
- hydrogen sulfur compounds;
- s alt;
- binary compounds with non-metals (carbon disulfide, chlorides);
- organic matter.
Now let's look at the main ones 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 oxidizing agent, since all of the listed elements are more electropositive. Let's take a look at some of the more important ones.
- Carbon disulfide - CS2. Transparent liquid with a characteristic pleasant aroma of ether. It is toxic, flammable and explosive. It is used as a solvent 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 industry, it is synthesized in large quantities.
- Hydrogen sulfide or hydrogen sulfide - H2S. A colorless gas with a sweet taste. The smell is sharp, extremely unpleasant, reminiscent of a rotten egg. Poisonous, depresses the respiratory center, as it binds copper ions. Therefore, when poisoned by them, suffocation and death occur. Widely used in medicine, organic synthesis, sulfuric acid production, and as an energy-efficient raw material.
- Metal sulfides are widely used in medicine, in sulfate production, in the production of paints, in the manufacture of phosphors and other places. The general formula is MexSy.
Compounds with an oxidation state of +4
Sulfur compounds 4 -it is predominantly an oxide and its corresponding s alts and an acid. All of them are fairly common compounds that have a certain value in industry. They can also act as oxidizing agents, but more often they exhibit reducing properties.
The formulas for sulfur compound with oxidation state +4 are as follows:
- oxide - sulfur dioxide SO2;
- acid - sulfurous H2SO3;
- s alts have the general formula Mex(SO3)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, it is formed during volcanic eruption, at this moment it is easy to identify by smell.
Dissolves in water with the formation of easily decomposing acid - sulfurous. It behaves like a typical acid oxide, forms s alts, which include SO32- as a sulfite ion. This anhydride is the main gas that affects the pollution of the surrounding atmosphere. This is what causes acid rain. In industry, it is used in sulphate production.
Compounds in which sulfur has an oxidation state of +6
These include, first of all, sulfuric anhydride and sulfuric acid with their s alts:
- sulfates;
- hydrosulfates.
Since the sulfur atom in them is in the highest degree of oxidation, the properties of these compounds are quite understandable. They are strong oxidizers.
Sulfur oxide (VI) - sulfuric anhydride - is avolatile colorless liquid. A characteristic feature is a strong moisture absorption capacity. Smokes outdoors. When dissolved in water, it gives one of the strongest mineral acids - sulfuric. Its concentrated solution is a heavy oily slightly yellowish liquid. If the anhydride is dissolved in sulfuric acid, then a special compound called oleum will be obtained. It is used industrially in the production of acid.
Among s alts - sulfates - compounds such as:
- gypsum CaSO4 2H2O;
- barite BaSO4;
- mirabilite;
- lead sulfate and others.
They are used in construction, chemical synthesis, medicine, the manufacture of optical instruments and glasses, and even the food industry.
Hydrosulfates are widely used in metallurgy, where they are used as a flux. And also they help to convert many complex oxides into soluble sulfate forms, which is used in the corresponding industries.
The study of sulfur in the school chemistry course
When is the best time for students to learn about what sulfur is, what are its properties, what is a 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 ground in the study of chemical science, when the foundations laid earlier will help to fully understand the topic. Therefore, it is the second half of the graduation year that is allocated for consideration of these issues.class. At the same time, the whole topic is divided into several blocks, in which there is a separate lesson "Sulfur compounds. Grade 9".
This is due to their abundance. The issue of industrial production of sulfuric acid is also considered separately. In general, an average of 3 hours is allotted for this topic.
But organic sulfur compounds are taken out for study only in the 10th grade, when organic issues are considered. They are also affected in biology in high school. After all, sulfur is part of such organic molecules as:
- thioalcohols (thiols);
- proteins (tertiary structure on which disulfide bridges form);
- thioaldehydes;
- thiophenols;
- thioethers;
- sulfonic acids;
- sulfoxides and others.
They are classified as 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 are the basis of many drugs (aspirin, sulfanilamide or streptocide).
In addition, sulfur is a constant component of compounds such as some:
- amino acids;
- enzymes;
- vitamins;
- hormones.
