Structural Chemistry & Crystallography Communication

Extended and in-depth theory of metallic bonds

The main problem is that, using X-rays, the types of crystal lattices of different metals were determined, and why they are so and not others is not yet known. For example, copper crystallizes in the fcc lattice, and iron in the bcc lattice, which when heated becomes fcc and this transition is used in heat treatment of steels. Usually in the literature, the metallic bond is described as carried out through the socialization of the outer electrons of the atoms and does not have the property of directionality. Although there are attempts (see below) to explain the directional metal bond since the elements crystallize into a specific type of lattice. The main types of crystal lattices of metals are body-centered cubic; face-centered cubic; hexagonal close-packed. It is still impossible in the general case to deduce the crystal structure of a metal from the electronic structure of the atom from quantum-mechanical calculations, although, for example, Ganzhorn and Delinger pointed out a possible connection between the presence of a cubic body-centered lattice in the subgroups of titanium, vanadium, chromium and the presence of valence d in the atoms of these metals -orbitals. It is easy to see that the four hybrid orbitals are directed along the four solid diagonals of the cube and are well suited for bonding each atom with its 8 neighbors in a body-centered cubic lattice. In this case, the remaining orbitals are directed to the centers of the unit cell faces and, possibly, can take part in the bond of the atom with its six second neighbors. The first coordination number (K.Ch.1) \ "8 \" plus the second coordination number (C.Ch.2) \ "6 \" in total is \ "14 \".

Author(s):

Henadzi Filipenka

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