Crystalline Solid (e.g. Quartz – Crystalline SiO2)
1. Particles are arranged in a regular, repeating three-dimensional lattice.
2. Long-range order is present throughout the crystal.
3. Has a sharp and definite melting point.
4. Shows anisotropy — physical properties vary with direction.
5. Breaks along definite cleavage planes.
6. X-ray diffraction pattern is sharp and well defined.
Amorphous Solid (e.g. Glass – Amorphous SiO2)
1. Particles are arranged randomly with no long-range order.
2. Only short-range order is present.
3. Does not have a sharp melting point; softens over a range of temperature.
4. Shows isotropy — physical properties are same in all directions.
5. Breaks irregularly without definite cleavage planes.
6. X-ray diffraction pattern is diffuse and not sharp.
Key Exam Note:
Quartz and glass both have the same chemical composition (SiO2) but different internal structures, hence different physical properties.