A crystalline solid is a solid in which the constituent particles (atoms, ions, or molecules) are arranged in a highly ordered and repeating 3D pattern, called a crystal lattice.
Key features of crystalline solids:
- Regular arrangement – Particles are in a fixed, repeating structure.
- Definite shape – They have well-defined geometrical shapes due to the orderly arrangement.
- Sharp melting point – They melt at a specific temperature because of uniform bonding.
- Anisotropy – Physical properties (like refractive index, conductivity) can vary in different directions.
- Long-range order – The order of particles extends throughout the entire solid.
Examples:
- Ionic crystalline solids: NaCl, KBr
- Molecular crystalline solids: Ice, Dry ice (CO₂)
- Metallic crystalline solids: Iron, Copper
- Covalent/network crystalline solids: Diamond, Quartz (SiO₂)