Covalent and metallic solids

Solids can be classified according to the nature of the bonding between their atomic or molecular components. The traditional classification distinguishes four kinds of bonding. Solids can be divided into three categories

  • Crystalline solids are three-dimensional analogs of a brick wall. They have a regular structure, in which the particles pack in a repeating pattern from one edge of the solid to the other.
  • Amorphous solids (literally, "solids without form") have a random structure, with little if any long-range order.
  • Polycrystalline solids are an aggregate of a large number of small crystals or grains in which the structure is regular, but the crystals or grains are arranged in a random fashion.
  • Properties :

    Solids are divided into two main categories, crystalline solids and amorphous solids .

    Crystalline solids

    Crystalline solids, or crystals, are regarded as "true solids." Minerals are crystalline solids. Common table salt is one example of this kind of solid. In crystalline solids, the atoms, ions or molecules are arranged in an ordered and symmetrical pattern that is repeated over the entire crystal. The smallest repeating structure of a solid is called a unit cell, which is like a brick in a wall. Unit cells combine to form a network called a crystal lattice.

    Amorphous solids

    Amorphous solids, the particles do not have a repeating lattice pattern. They are also called "pseudo solids." glass, rubber, gels and most plastics are examples of it . An amorphous solid does not have a definite melting point; instead, it melts gradually over a range of temperatures, because the bonds do not break all at once. This means an amorphous solid will melt into a soft, malleable state before turning completely into a liquid.