Polymorphism

Write a note on: Polymorphism.

(i) A single substance that exists in two or more crystalline structures is said to be polymorphous.

(ii) Polymorphs of a substance are formed under different conditions.

(iii) Polymorphism occurring in elements is called

(iv) Example of polymorphous forms: CaCO3: (Calcite and aragonite) Silica:

 (α quartz,ẞ- quartz, cristobalite, etc.)

(v) Example of allotropic forms: Diamond, graphite fullerene etc. [carbon.]

 Define. Anisotropy .

Ans. The ability of crystalline solids to change values of physical properties when measured in different directions is called anisotrophy.