The nature of crystal lattices in single crystals of pure metals.
The main problem is that, using X-rays, the types of crystal lattices of different metals were determined, and why they are such 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 (K.Ch.2) \ "6 \" in total is \ "14 \".
Let us show that the metallic bond in the closest packing (HEC and FCC) between the centrally selected atom and its neighbors, in the general case, is presumably carried out through 9 (nine) directional bonds, in contrast to the number of neighbors equal to 12 (twelve) (coordination number).
In the literature, there are many factors affecting crystallization, so I decided to remove them as much as possible, and the metal model in the article, let's say, is ideal, i.e. all atoms are the same (pure metal), crystal lattices without inclusions, without interstices, without defects, etc. Using the Hall effect and other data on properties, as well as calculations by Ashcroft and Mermin, for me the main factor determining the type of lattice turned out to be the outer electrons of the core of an atom or ion, which resulted from the transfer of some of the electrons to the conduction band.
It turned out that the metallic bond is due not only to the sharing of electrons, but also to the external electrons of the atomic cores, which determine the direction or type of the crystal lattice.
Let's try to connect the outer electrons of an atom of a given element with the structure of its crystal lattice, taking into account the need for directed bonds (chemistry) and the presence of socialized electrons (physics) responsible for the galvanomagnetic properties.
see the main part of the work on p.
https://natureofchemicalelements.blogspot.com
I believe that the main achievement of my work is that the real first coordination number for atoms in single crystals of pure metals (fcc and HEC crystal lattices) was determined equal to 9 or 15. This number was deduced from the physical and chemical properties of crystals.
About bond electrons in single crystals of metals, which determine the type of crystal lattice.
For potassium, sodium, rubidium, cesium in the conduction band, 1 electron and 8 bond electrons each - the Hall constant is negative (in the conduction band, one electron from an atom), the type of bcc lattice ... each selected atom has 8 neighbors in the crystal lattice ...
Nickel, copper, silver, platinum, palladium and gold have an fcc lattice ... crystallization requires 15 bond electrons from an atom ... let's look at nickel as an example 1s2 2s2 2p6 3s2 3p6 3d8 4s2 external electrons in total 16 (3p6 3d8 4s2) one went into the conduction band 15 entered into communication with neighboring atoms ... this one electron from the conduction band is checked by the Hall constant, if it is negative, then in the conduction band, 1-2 electrons, and if positive, then, as a rule, more than two.
Magnesium - 2 electrons are bonded to the nucleus, 9 bond electrons (GEK) and one electron in the conduction band - Hall constant is negative, aluminum - 2 electrons are bonded to the nucleus, 9 bond electrons (FCC) and two electrons in the conduction band - Hall constant is negative.
In metal crystals, atoms are united not only by the socialization of conduction electrons, but also by bond electrons, which were revealed in my work.
For some single crystal elements, I may be mistaken in counting the bond electrons (9 + 6 or 12 + 3), which affect the formation of a particular type of crystal lattice. However, it seems to me that such a pattern exists.