The formation of a chemical bond involvesthe process of redistribution of electron densities, which originally belonged to different atoms. In connection with the fact that electrons on the outer level with the core are connected least firmly, they also play the main role in the formation of the connection. The number of bonds that is formed by an atom during a connection is called valency. Accordingly, electrons participating in the formation of a bond are called valence electrons. In the energy plan, there are atoms of different stability. The most stable is one with two or eight electrons at the outer level (the maximum number). In this case, this level will be considered complete. Such completed levels are characteristic of atoms contained in noble gases. In this connection, under ordinary conditions, they are in a state of a monatomic gas, chemically inert.
For atoms of other elements are characteristicincomplete levels. When a chemical reaction occurs, the levels of the outer order are completed. This is due to the recoil or attachment of electrons, as well as through the formation of common pairs. So, a covalent and ionic bond is formed. The properties of atoms in this case are manifested in their striving to acquire a stable electronic shell of external significance. It will be either two-electron or eight-electron. This regularity is considered the basis of the theory of chemical bonding.
Formation of the connection occurs inaccompanied by the allocation of a sufficiently large amount of energy. In other words, communication is formed exothermically. This is due to the fact that new particles (molecules) appear, which under normal conditions have greater stability.
Electronegativity is one of the main features that indicate the nature of the emerging connection. This feature is manifested in the ability of atoms to attract electrons from other atoms.
Electrostatic attraction between ions isionic chemical bond. Such an interaction is possible between atoms with a sharply differing electronegativity. The ionic bond forms the corresponding ionic compounds. They consist of individual molecules exclusively in the vapor state. The ionic bond in the compounds of the crystalline (solid) state provides for the interaction of ions (negative and positive) located regularly. In this case there are no molecules.
Compounds that are characterized by an ionic bond,form the elements of the main subgroups of 1,2,6,7 groups. There are relatively few such connections. These include, for example, inorganic salts (NH4Cl), saline organic substances (amine salts and others).
Non-polar covalent and ionic bonds aretwo limiting cases of the electron density distribution. The first is characterized by a uniform distribution between identical particles (atoms) of the binder of two electron clouds. In the ionic bond, the electron cloud belongs almost entirely to one of the atoms. However, in most of the compounds, the interactions are at the intermediate level. In other words, they form a polar covalent bond.
Interaction arising from the formation ofcommon electronic pairs, is covalent. Covalent bond, which appeared due to the interaction of atoms with different electronegativity, is considered polar. The electron density from the binding electron pair is shifted to an atom whose electronegativity is greater. Examples of such molecules are H2S, NH3, H2O, and others. In these compounds, the appearance of a covalent (nonpolar and polar) bond is due to unpaired electrons of the binding atoms.
