In the process of forming a chemical bond electron density, which originally belonged to different atoms are redistributed in space.Less strongly interact with the core electrons of the external level.They perform a major role in the formation of chemical bonds.The electrons that are involved in the process, called the valence.But she had a chemical bond - valence.In p- and s-valence elements are the outer electrons from the d-elements - the last (external) s- and d-electrons penultimate.There atoms less or more stable.The latter include those outer layer which contains the maximum number of electrons (two and eight).This level is considered complete.Completed levels are characterized by greater strength.They are inherent in the atoms of the noble gases, in this connection under normal conditions their condition is an inert monatomic gas.
to atoms of other elements characteristic of unfinished levels.In the course of a chemical reaction takes place the completion of the external value of the levels.This is achieved or the impact, or the addition of electrons.Completion levels may be common and formation of steam.These methods contribute to the formation of two major types of bond: ionic and covalent.In the formation of the molecule, so the atoms are trying to buy electronic stability (external) or vosmielektronnuyu or two-electron.This pattern is the basis of the theory of the formation of chemical bonds.Education through the completion of the outer valence level of the corresponding atom is accompanied by the release of significant amounts of energy.The formation of chemical bonding, in other words, always proceeds exothermically, due to the fact that the molecules appear (new particles), which are more stable under ordinary conditions.
As one of the most important indicators, defining the nature of communication, acts electronegativity.It is the ability of an atom to attract electrons of other atoms.Change electronegativity occurs gradually.Thus, in the period of the system increases the value of this parameter left to right.Decreasing the values for groups comes from the top down.It is the formation of covalent compounds by forming bonding (shared) electron pairs.
in liquid, solid state in metals there are metal chemical bond.According to the provision in the periodic system, atoms of these elements have a small number of valence electrons (one to three).In addition, they noted, and low energy "electron detachment" (ionization).In this regard, the metallic bond - it is a weak link.Electrons in an atom are held loosely, come off quite easily, while having the ability to move throughout the crystal.Metallic bond presupposes free atoms.Part of the valence electrons, endowed with the ability to move freely within the crystal lattice, form the "electron gas".With it, the metallic bond is formed.There it is due to the "socialization" of valence electrons of atoms.It should be noted that the metallic bond has its own characteristics.Since forming its electrons have the ability to move throughout the volume element.In this regard, the metal acquire a number of characteristic features.In particular, these include luster, good electrical conductivity, thermal conductivity, ductility, malleability, and others.Metallic elements in communication provides a relatively high resilience.
