JEE Main & Advanced Chemistry The Solid State / ठोस प्रावस्था Formation of crystal and Crystal systems

The crystals of the substance are obtained by cooling the liquid (or the melt) of the solution of that substance. The size of the crystal depends upon the rate of cooling. If cooling is carried out slowly, crystals of large size are obtained because the particles (ions, atoms or molecules) get sufficient time to arrange themselves in proper positions.

Atoms of molecules \[\xrightarrow{\text{Dissolved }}\] cluster \[\xrightarrow{\text{dissolved}}\] dissolved embryo \[\to \underset{\text{(unstable)}}{\mathop{\text{nucleus }}}\,\] \[\to \] crystal

(If loosing units dissolves as embryo and if gaining unit grow as a crystals).

Bravais (1848) showed from geometrical considerations that there can be only 14 different ways in which similar points can be arranged. Thus, there can be only 14 different space lattices. These 14 types of lattices are known as Bravais Lattices. But on the other hand Bravais showed that there are only seven types of crystal systems.

Bravais lattices corresponding to different crystal systems