When performing many physical and chemical reactions, the substance passes into a solid state of aggregation. At the same time, molecules and atoms tend to settle down in such a spatial order that the interaction forces between the particles of a substance would be as balanced as possible. This achieves the strength of a solid. Atoms, once having occupied a definite position, make small oscillatory motions, 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 ideas about 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.
Crystal lattice definition
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, in addition to the nodes at the vertices of the lattice, there is a node and in a place where imaginary diagonals of the parallelepiped intersect, then you have a face-centered type of lattice.
Types of crystal lattices
The various microparticles that make up the substance determine the different types of crystal lattices. They can determine the principle of building the relationship between microparticles inside a crystal. Physical types of crystal lattices - ionic, atomic and molecular. This also includes various types of metal crystal lattices. The study of the principles of the internal structure of elements involved in chemistry. Types of crystal lattices are presented in more detail 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 Crystalline Lattices
This type of substance structure is inherent in elements whose structure is determined by a covalent chemical bond. Types of crystal lattices of this kind contain separate atoms in the nodes, which are interconnected by strong covalent bonds. A similar type of bond arises when two identical atoms "share" electrons, thereby forming a common pair of electrons for neighboring atoms. Due to this interaction, covalent bonds evenly and strongly bind atoms in a certain order. Chemical elements that contain atomic types of crystal lattices have hardness, high melting point, poorly conduct electrical current and are chemically inactive. The classic examples of elements with a similar internal structure include diamond, silicon, germanium, and boron.
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.
Crystal-forming molecules can be both polar and non-polar. Due to the spontaneous movement of electrons and the oscillations of nuclei in molecules, the electric equilibrium can shift - this is how an instantaneous electric dipole moment occurs. Properly oriented dipoles create attractive forces in the lattice. Carbon dioxide and paraffin are typical examples of elements with a molecular lattice.
Metal crystal lattices
The metallic bond is more flexible and plastic than ionic, although it may seem that both of them are based on the same principle. The types of metal lattices explain their typical properties, such as mechanical strength, thermal and electrical conductivity, and 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. Connection with ions in the crystal lattice of metals is not durable, so electrons easily leave its limits. The electrons move along power lines, leaving behind positively charged ions.
Chemistry pays great attention to the study of the internal structure of matter. The types of crystal lattices of various elements determine almost the entire spectrum of their properties. By acting on the crystals and changing their internal structure, it is possible to achieve the enhancement of the desired properties of the substance and remove undesirable, convert chemical elements. Thus, the study of the internal structure of the surrounding world can help to know the essence and principles of the structure of the universe.