When many physical and chemical reactions are carried out, the substance passes into a solid aggregate state. In this case, molecules and atoms tend to settle in such a spatial order, in which the forces of interaction between the particles of matter would be as balanced as possible. This achieves the solidity of the solid. Atoms once occupy a certain position, perform small oscillatory movements, the amplitude of which depends on temperature, but their position in space remains fixed. The forces of attraction and repulsion balance each other at a certain distance.
Modern concepts of the structure of matter
Modern science says that the atom consists of a charged nucleus, carrying a positive charge, and electrons carrying negative charges. At a speed of several thousands of trillions of times per second the electrons revolve in their orbits, around the nucleus creating an electron cloud. The positive charge of the nucleus is numerically equal to the negative charge of electrons. Thus, the atom of matter remains electrically neutral. Possible interactions with other atoms occurs when electrons detach from the atom, thereby breaking the electric balance. In one case, the atoms are arranged in a certain order, which is called a crystal lattice. In the other, due to the complex interaction of nuclei and electrons combine into molecules of various types and complexity.
Determination of the crystal lattice
Together different types of crystal lattices of substances represent a mesh with different spatial orientation, the nodes of which are ions, molecules or atoms. It is a stable geometric spatial position and is called the crystal lattice of the substance. The distance between the nodes of a single crystal of the cell is called the period of identity. The spatial angles of the nodes in the cell, are called parameters. According to the method of constructing relationships of the crystal lattice can be simple, basicunderstanding, face-centered and body-centred. If the particles are located only at the corners of a parallelepiped, such a lattice is called simple. An example of such grid is shown below:
If, in addition to nodes, the particles located in the middle of the spatial diagonals, such a construction of the particles in a substance is called body-centred crystal lattice. In the figure this shown clearly.
If there is a node besides nodes in the vertices of the lattice and in the place where the imaginary diagonals of the parallelepiped intersect, then you have a face-centered lattice type.
Types of crystal lattices
Different microparticles, of which the substance consists, determine different types of crystal lattices. They can determine the principle of constructing the connection between the microparticles inside the crystal. The physical types of crystal lattices are ionic, atomic, and molecular. This also includes different types of crystal lattices of metals. The study of the principles of the internal structure of elements deals with chemistry. The types of crystal lattices are detailed below.
Ionic crystal lattices
These types of crystal lattices present in compounds with ion type of coupling. In this case, the lattice sites contain ions having opposite electric charge. Through the electromagnetic field, power Legionowo interactions are strong enough, and this causes the physical properties of the substance. The usual characteristics are refractoriness, density, hardness and ability to conduct an electric current. Ion types of crystal lattices are such substances as common salt, potassium nitrate, and others.
Atomic crystal lattices
This type of structure of matter is inherent in elements whose structure is determined by the covalent chemical bond. Types of crystal lattices of this kind contain individual atoms in the nodes, bound together by strong covalent bonds. A similar type of connection occurs when two identical atoms "divide" by electrons, thereby forming a common pair of electrons for neighboring atoms. Due to this interaction, covalent bonds connect atoms uniformly and strongly in a certain order. Chemical elements that contain atomic types of crystal lattices have hardness, high melting point, poorly conduct electric current and are chemically inactive. Classical examples of elements with a similar internal structure include diamond, silicon, germanium, boron.
Molecular crystal lattices
Substances with a molecular type of crystal lattice represent the system sustainable, interactive, tightly Packed between the molecules located in the crystal lattice. In these compounds the molecules retain their spatial position in the gaseous, liquid and solid phase. In knots of a crystal the molecules are held together with weak van der Waals forces, which is ten times weaker than forces of ionic interaction.
The molecules forming the crystal can be both polar and nonpolar. Because of the spontaneous motion of electrons and the vibrations of nuclei in molecules, the electric equilibrium can shift - this is how the instantaneous electric moment of the dipole arises. Correspondingly, oriented dipoles create attractive forces in the lattice. Carbon dioxide and paraffin are typical examples of elements with a molecular crystal lattice.
Metal crystal lattices
The metal bond is more flexible and more plastic than the ionic one, although it may seem that both are based on the same principle. Types of crystal lattices of metals explain their typical properties - such, for example, as mechanical strength, heat and electrical conductivity, fusibility.
The distinctive feature of a metallic crystal lattice is the presence of positively charged metal ions (cations) to the nodes of the lattice. Between nodes are electrons which are directly involved in the generation of an electric field around the grid. The number of electrons moving inside of this crystal lattice is called the electron gas. In the absence of electric field the free electrons make chaotic motion, randomly interacting with the ions of the lattice. Every interaction changes the momentum and direction of motion of negatively charged particles. An electric field, the electrons attract cations, balancing their mutual repulsion. Although the electrons are considered free, they don't have enough energy to leave the crystal lattice, so these are charged particles that reside within it.
The presence of an electric field gives additional energy to the electron gas. The connection with ions in the crystal lattice of metals is not strong, so the electrons easily leave it. Electrons move along the lines of force, leaving behind positively charged ions.
Chemistry is of great importance to the study of the internal structure of matter. The types of crystal lattices of various elements determine practically the entire range of their properties. By acting on the crystals and changing their internal structure, one can achieve the enhancement of the desired properties of the substance and remove the unwanted, transform chemical elements. Thus, the study of the internal structure of the surrounding world can help to understand the essence and principles of the universe.