Allotropic modifications

Allotropy refers to the ability of atoms of one element to form different types of simple substances. So the connections are different from each other.

Allotropic modifications are stable. Under conditions of constant pressure at a certain temperature, these substances can pass into one another.

Allotropic modifications can be formed from molecules with different numbers of atoms. For example, the element Oxygen forms ozone (O3) and the actual substance is oxygen (O2).

Allotropic modifications may be solids having different crystal structures. These compounds include, for example, diamond and graphite. These substances are allotropic modifications of carbon. This chemical element can form five simple substances: hexagonal and cubic diamond, graphite, carbine (in two forms).

Hexagonal diamond is found in meteorites and obtained under laboratory conditions with prolonged heating under the influence of very high pressure.

Diamond, as is known, is the hardest of all substances that exist in nature. It is used when drilling rocks and cutting glass. Diamond is a colorless transparent crystalline substance, which has a high refractive index. The diamond crystals have a cubic face-centered lattice. Half of the atoms of the crystal are located in the centers of the faces and vertices of one cube, and the remaining half of the atoms are in the centers of the faces and vertices of the other cube, which is displaced relative to the first in the direction of the spatial diagonal. Atoms form a tetrahedral three-dimensional grid in which they have covalent bonds.

Of all the simple substances, only in diamond is the maximum number of atoms that are very dense. Therefore, the compound is very strong and solid. Strong bonds in carbon tetrahedra provide high chemical resistance. The diamond can only be affected by fluorine or oxygen at a temperature of eight hundred degrees.

Without access to air, the diamond turns into graphite under strong heating. This substance is represented by crystals of dark gray color. Graphite has a weak metallic luster. The substance is oily to the touch. Graphite is resistant to heat, has a relatively high thermal and electrical conductivity. The substance is used in the manufacture of pencils.

Carbynes are produced synthetically. It is a solid substance of black color with a glassy sheen. Without air access, when heated, the carbine turns into graphite.

There is another form of carbon - amorphous carbon. This disordered structure is obtained by heating the carbon-containing compounds. Large deposits of coal are found in natural conditions. In this case, the substance has several varieties. Coal can be presented in the form of soot, bone coal or coke.

As already mentioned, allotropic modifications of one element are characterized by a different interatomic structure. In addition, they are endowed with various chemical and physical properties.

Sulfur is another element capable of allotropy. This substance is used by man since ancient times. There are different allotropic modifications of sulfur. The most popular is rhombic. It is represented by a yellow solid. The rhombic sulfur is not wetted by water (floats on the surface). This property is used in the extraction of matter. Rhombic sulfur is soluble in organic solvents. The substance has poor electrical and thermal conductivity.

In addition, there is plastic and monoclinic sulfur. The first is a brown amorphous (similar to rubber) mass. It is formed if molten sulfur is poured into cold water. Monoclinic is represented in the form of dark yellow needles. Under the influence of room temperature (or the temperature approximating to it), both these modifications transform into rhombic sulfur.