Metal bonding
In the process of forming a chemical bondElectronic densities, which originally belonged to different atoms, are redistributed in space. The interaction with the core of external-level electrons is less stable. It is they who play the main role in the formation of chemical bonds. The electrons that participate in this process are called valence electrons. And the chemical bond itself is valency. The p- and s-elements are external electrons, the d-elements have the last (external) s- and the penultimate d-electrons. There are atoms that are less or more stable. The latter include those whose external level 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 noble gases, and therefore under normal conditions their state is an inert monatomic gas.
For atoms of other elements are characteristicincomplete levels. In the course of the chemical reaction, the levels of external significance are completed. These are achieved either by recoil or by the attachment of electrons. Completion of levels can be carried out and the formation of common pairs. These methods contribute to the formation of two main types of bonds: ionic and covalent. When a molecule is formed, thus, the atoms try to acquire a stable electronic shell (external): either an eight-electron shell or a two-electron shell. This regularity underlies the theory of the formation of chemical bonds. The formation of valency by completing the external level in the corresponding atoms is accompanied by the release of a significant amount of energy. The formation of a chemical bond, in other words, always proceeds exothermically, in connection with the appearance of molecules (new particles) that have greater stability under normal conditions.
As one of the significant indicators,The electronegativity is the determining factor of the connection. This is the ability of an atom to attract electrons from other atoms. The change in electronegativity is gradual. Thus, in the periods of the system the value of this indicator increases from left to right. Reducing the same value occurs in groups from top to bottom. Covalent compounds include formations due to the formation of binding (common) electron pairs.
In the liquid, solid state in metals, there existsmetal chemical bonding. According to the position in the periodic system, the atoms of the elements under consideration have a small number of valence electrons (one to three). In addition, they have a low energy of "electron detachment" (ionization). In this connection, the metal bond is a rather weak connection. The electrons in the atom are kept weakly, they break off easily enough, while being able to move around the crystal. The metal bond assumes the presence of free atoms. Part of the valence electrons, endowed with the ability to move freely within the crystal lattice, form an "electron gas". With its help, a metallic bond is formed. It arises due to the "socialization" of valence electrons by atoms. It should be noted that the metal bond has its own characteristics. So, the electrons forming it have the ability to move throughout the volume of the element. In this connection, metals acquire a number of characteristic features. In particular, they include gloss, good electrical conductivity, thermal conductivity, ductility, ductility and others. The metal bond provides relatively high reduction ability in the elements.
