Give the differences between crystalline and amorphous solids with respect to shape and melting point.

Explanation

Crystalline solids:
(i) They have a regular three dimensional arrangement of atoms, ions or molecules due to which they have well defined geometrical shape.
(ii) They have long range order.
(iii) They have sharp melting point, i.e., they melt at a particular temperature. (v) They have high and fixed heat of fusion, i.e.,high energy is required to melt 1 mole of crystalline splid.
(vi) They are anisotropic , i.e., they have different optical and electrical properties in different directions.
(vii) They are true solids , i.e.,they show all the characteristic properties of solids.
(viii) They are used for making optical instruments like calcite crystal is used in prism . Glass slab is also made up of a crystalline substance .
Amorphous solids:
(i) They do not have regular arrengement of particles , therefore do not have well defined shape .
(i) They have short range order .
(iii) They do not have sharp melting point , i.e., they melt over a range of temperature.
(iv) They give irregular structure on cleavage.
(v) They do not have fixed heat of fusion .
(vi) They are isotropic , i.e., they have same properties in all directions.
(vii) They are pseudo-solids , i.e., they do not show all the characteristic properties of solids. They are also called super-cooled liquids.
(viii) They are used as photovoltaic material ,i.e., can convert sunlight into electricity , e.g., amorphous silica is photovoltaic substance.