Any substance in nature, as is known, is composed of smaller particles.They, in turn, are connected to form a specific structure that defines the properties of a substance.
atomic crystal lattice characteristic of solids and occurs at low temperatures and high pressure.In fact, it is thanks to this structure, diamond, metals and other materials acquired characteristic durability.
structure of these substances at the molecular level looks like a crystal lattice, each atom of which is linked with its neighbor most durable compound existing in nature - a covalent bond.All the tiny elements that make up the structure, located in an orderly and regular intervals.Representing the net, in the corners where the atoms are located, always surrounded by the same number of satellites, atomic crystalline lattice practically does not change its structure.It is generally known that change the structure of the pure metal or alloy may be merely heating it.When the temperature is higher, the stronger bonds in the lattice.
In other words, the atomic crystal lattice is the key to the strength and hardness of materials.This, however, should take into account that the arrangement of atoms in various substances can also be different, which in turn affects the degree of strength.For example, diamond and graphite, having a composition the same carbon atom, essentially different from each other in terms of strength: diamond - the hardest substance in the world, the graphite can exfoliate and break.The fact that in the crystal lattice of graphite atoms are arranged in layers.Each layer resembles a bee cell in which carbon atoms are articulated quite weak.This structure leads to the crumbling layered pencil leads: in case of breakage of the graphite is simply peeled off.Another thing - the diamond crystal lattice which consists of excited atoms, ie, those that are able to form 4 strong bonds.Destroy a joint impossible.
metal lattice, in addition, possess certain characteristics:
1. The lattice - a value determined by the distance between the centers of two adjacent atoms measured along the edge of the grid.The conventional notation is different from thereof in mathematics: a, b, c - the length, width, height of the lattice, respectively.Obviously, the size of the figures are so small that the distance is measured in the smallest units - a tenth of a nanometer, or angstroms .
2. To - coordination number .The index, which determines the packing density of atoms in a single array.Correspondingly, its density is greater, the higher the number K. In fact, this figure also represents the number of atoms that are as close as possible, and at equal distance from the atom studied.
3. Basis lattice .Also, the value characterizing the density of the grid.It represents the total number of atoms that belong to a particular cell being studied.
4. compactness factor is measured by counting the total lattice divided by the volume that they occupy all the atoms in it.Like the previous two, this value reflects the density of the studied grating.
We have considered only a few substances, which is characteristic of the atomic crystal lattice.Meanwhile, a great number of them.Despite the great diversity crystalline atomic lattice includes units is always connected by a covalent bond (polar or nonpolar).Furthermore, such substances are practically insoluble in water and have low thermal conductivity.
In nature there are three types of crystal lattices: the cubic body-centered, face-centered cubic, hexagonal close-packed.
