If a crystalline solid is cut with a sharp object, it would always give parts with smooth edges whereas an amorphous solid would cut into surfaces with rough, uneven edges. Crystalline solids are therefore said to have cleavage property, and amorphous solids do not show cleavage property.
Amorphous solids are said to be isotropic, and crystalline solids are anisotropic for their physical property measurements.
Isotropy comes from the Greek word; iso means same and tropos means direction. The name rightly indicates that for the amorphous solids; the physical property measurements are same in all the directions. The same correlation applies for anisotropy that means no same direction. It means that for the crystalline solids, the physical property measurements are not same in all the directions.
Crystalline Solids | Amorphous solids | |
|---|---|---|
| Arrangement | The constituent particles are arranged in a regular order | The constituent particles show disordered arrangement |
| Order | Exhibit both long-range and short-range order | Exhibit only short-range order |
| Melting Point | Have sharp melting points | Solids melt over a range of temperatures |
Solids are made up of many particles, and depending on how they are arranged, solids can be divided into crystalline solids and amorphous solids.
The particles may be atoms, ions, or molecules.
For example, gold atoms, NaCl ions, and sucrose molecules compose the solid-state.
Lattice points are the positions an atom, ion, or molecule can occupy in a crystal giving it its shape and characteristics. If any of these particles go missing or are not in a correctly ordered arrangement, it can introduce a defect in the crystal. Lattice points are essentially a crystalline framework.
- The unit cells that makes up the entire crystalline solid has a fixed value for the length of the edges and the angle between the edges.
- As the Crystalline solids are made up of a large number of unit cells extending in all the three dimensions, properties of the unit cell dictate the properties of the crystalline solid.
- Each unit cell has a fixed value for the length of the edges and the angle between the edges.
The crystalline solid is made up of the unit cells. Therefore, the properties of the unit cell turn out to be the properties of the crystalline solid. In a unit cell, the length of the edges and the angle between the edges are fixed. Therefore, the entire crystalline solid would exhibit fixed value for both these parameters.
