i. Crystalline solids:
a. A crystalline solid usually consists of a large number of small crystals, each of them having a definite characteristic geometrical shape. These tiny crystals are called unit cells.
c. Crystalline solids have long range order which means that there is a regular pattern of arrangement of particles (atoms, ions or molecules) which repeats itself periodically over the entire crystal.
eg. Sodium chloride and quartz
ii. Amorphous solids:
a. The arrangement of constituent particles (atoms, molecules or ions) in amorphous solids has only short range order.
c. Such portions are scattered and in between, arrangement is disordered.
eg. glass, rubber, plastics and amorphous silicon.