“A phenomenon in which a single substance exists in two or more crystal structures is called “POLYMORPHISIM” while the substance is polymorphous, e.g.
Graphite (carbon) Trigonal
Diamond (carbon) Tetrahedral
“A phenomenon in which many substances exits in a single crystalline form is called ISOMORPHISM” While substance is called Isomorphous.
NaCI Cubical Crystal
AgNO3 Cubical Crystal
The smallest unit of any crystalline substance, is called “Unit cell”.
CRYSTAL LATTICE AND LATTICE ENERGY:
When the particles of any crystalline substance are replaced by dots then crystal lattice are observed. While the amount of heat energy released when one mole of any crystalline substance form “CRYSTAL LATTICE” is called “LATTICE ENERGY”.