Crystalline and amorphous solids are solid. Crystal - so in ancient times called ice. And then they began to call crystal quartz and rock crystal, considering these minerals to be petrified ice. Crystals are natural and artificial (synthetic). They are used in the jewelry industry, optics, radio engineering and electronics, as supports for elements in high-precision instruments, as an ultrahard abrasive.
Crystalline bodies are characterized by hardness, have a strictly regular position in the space of molecules, ions or atoms, resulting in the formation of a three-dimensional periodic crystal lattice (structure). Outwardly this is expressed by a certain symmetry of the shape of a solid and its specific physical properties. In external form, crystalline bodies reflect the symmetry inherent in the internal "packing" of particles. This determines the equality of the angles between the faces of all the crystals consisting of the same substance.
In them the distances from the center to the center between neighboring atoms will be equal (if they are located on the same straight line, this distance will be the same over the entire length of the line). But for atoms lying on a straight line with a different direction, the distance between the centers of the atoms will be different. This circumstance explains the anisotropy. Anisotropy is the main thing, how do crystalline bodies differ from amorphous ones.
More than 90% of solids can be attributed to crystals. In nature, they exist in the form of single crystals and polycrystals. Monocrystals are single, whose faces are represented by regular polygons; They are characterized by the presence of a continuous crystal lattice and anisotropy of physical properties.
Polycrystals - bodies consisting of many small crystals, "fused" with each other somewhat chaotically. Polycrystals are metals, sugar, stones, sand. In such bodies (for example, a fragment of a metal), the anisotropy is usually not manifested due to the disordered arrangement of the elements, although an anisotropy is inherent in an individual crystal of this body.
Other properties of crystalline bodies: a strictly defined crystallization and melting temperature (the presence of critical points), strength, elasticity, electrical conductivity, magnetic conductivity, thermal conductivity.
Amorphous - not having a form. This word is translated literally from Greek. Amorphous bodies are created by nature. For example, amber, wax, volcanic glass. Man - glass and resins (artificial), paraffin, plastics (polymers), rosin, naphthalene, var., Are involved in the creation of artificial amorphous bodies. Amorphous substances do not have a crystal lattice because of the chaotic arrangement of molecules (atoms, ions) in the structure of the body. Therefore, the physical properties for any amorphous body are isotropic - they are the same in all directions. For amorphous bodies there is no critical point of the melting point, they gradually soften when heated and pass into viscous liquids. Amorphous bodies are allocated an intermediate (transitional) position between liquids and crystalline bodies: at low temperatures they harden and become elastic, in addition, they can split at impact on the shapeless pieces. At high temperatures, these same elements manifest plasticity, becoming viscous liquids.
Now you know what crystalline bodies are!