Allotropic oxygen modifications: comparative characteristic and value

Atoms of one kind can be part of different substances. For an element designated by the symbol "O" (from the Latin name Oxygenium), two common simple substances are known in nature. The formula of one of them is O _{2, the} second one is O _3. These are allotropic modifications of oxygen (allotropes). There are other compounds, less stable (O ₄ and O ₈ ). To understand the difference between these forms will help to compare molecules and properties of substances.

What are allotropic modifications?

Many chemical elements can exist in two, three or more forms. Each of these modifications is formed by atoms of the same species. The scientist J. Berzellius in 1841 was the first to call such a phenomenon an allotropy. The open regularity was originally used only for the characterization of substances of molecular structure. For example, two allotropic modifications of oxygen are known, the atoms of which form molecules. Later, researchers established that the modifications may be among the crystals. According to modern concepts, allotropy is one of the cases of polymorphism. Differences between forms are caused by mechanisms of formation of a chemical bond in molecules and crystals. This feature is manifested mainly elements of groups 13-16 of the periodic table.

How does a different combination of atoms affect the properties of matter?

Allotropic modifications of oxygen and ozone are formed by the atoms of the element with the atomic number 8 and the same number of electrons. But they differ in structure, which caused a significant discrepancy in properties.

Conclusions from the results of the comparison: allotropic modifications of oxygen do not differ in qualitative composition. The structure of the molecule is reflected in the physical and chemical properties of the substances.

Is the same amount of oxygen and ozone in nature?

The substance, the formula of which O ₂ , is found in the atmosphere, hydrosphere, earth crust and living organisms. About 20% of the atmosphere is formed by diatomic oxygen molecules. In the stratosphere at an altitude of about 12-50 km from the earth's surface there is a layer known as the "ozone screen". Its composition reflects the formula O ₃ . Ozone protects our planet by absorbing the dangerous rays of the red and ultraviolet spectrum of the Sun. The concentration of the substance is constantly changing, and its average value is low - 0.001%. Thus, O ₂ and O ₃ are allotropic modifications of oxygen, which have significant differences in their distribution in nature.

How to get oxygen and ozone?

Molecular oxygen is the most important simple substance on Earth. It forms in the green parts of plants in the light during photosynthesis. With electric discharges of natural or artificial origin, the diatomic oxygen molecule breaks up. The temperature at which the process starts is about 2000 ° C. Some of the radicals that have arisen combine again to form oxygen. Some active particles react with diatomic oxygen molecules. In this reaction, ozone is produced, which also reacts with free oxygen radicals. In this case, diatomic molecules arise. Reversibility of the reactions leads to the fact that the concentration of atmospheric ozone is constantly changing. In the stratosphere, the formation of a layer consisting of O ₃ molecules is associated with ultraviolet radiation of the Sun. Without this protective screen, dangerous rays could reach the surface of the Earth and destroy all forms of life.

Allotropic modifications of oxygen and sulfur

The chemical elements O (Oxygenium) and S (Sulfur) are located in the same group of the periodic table, they are characterized by the formation of allotropic forms. Of molecules with different numbers of sulfur atoms (2, 4, 6, 8) under normal conditions, the most stable is S8, resembling a crown in shape. The rhombic and monoclinic sulfur are constructed from such 8-atom molecules.

At a temperature of 119 ° C, the monoclinic yellow form forms a brown, viscous mass, a plastic modification. The study of allotropic modifications of sulfur and oxygen is of great importance in theoretical chemistry and practical activity.

Oxidizing properties of various forms are used on an industrial scale. Ozone is used for disinfection of air and water. But at concentrations above 0.16 mg / m3, this gas is dangerous for humans and animals. Molecular oxygen is essential for respiration, it is used in industry and medicine. Allotropes of carbon (diamond, graphite), phosphorus (white, red) and other chemical elements play an important role in economic activity.