Classification of Solids 


 

Solids are classified into two categories on the basis of the nature of order present in the arrangement of their constituent particles

1. Crystalline Solids

 They are rigid, incompressible and anisotropic (i.e. some of their physical properties like electrical resistance show different values when measured along different directions in the same crystal). Crystalline solids have long range order which means that there is a regular pattern of arrangement of particles which repeats itself periodically over the entire crystal. Crystalline solids have a sharp melting point while amorphous solids soften over a range of temperature and can be moulded and blown into various shapes.

2. Amorphous Solids

 They are isotropic, i.e. value of any physical property would be same along any direction. They have short range order of packing. In such an arrangement, a regular and periodically pattern is observed over short distances only. SiO, (silica) can be amorphous or crystalline. In quartz silica (crystalline), all the four corners of Sio tetrahedron are shared by others to give a network solid. In amorphous silica, SiO tetrahedra are joined at random to form polymeric chains, sheets or three dimensional units.