Solid – Crystalline

Solid – Crystalline have a well-defined, repeating atomic structure extending in all three spatial dimensions.

Characteristics of Solid – Crystalline:

• Long-Range Order: Atoms or molecules are arranged in a repeating pattern.
• Anisotropy: Physical properties depend on the direction due to the ordered structure.
• Sharp Melting Point: Crystalline solids melt at a specific temperature.

Types of Crystals:

• Ionic Crystals:

  • Composed of ions held together by electrostatic forces.
  • Example: Sodium chloride (NaCl).

• Covalent Crystals:

  • Atoms are connected by covalent bonds in a continuous network.
  • Example: Diamond (carbon).

• Metallic Crystals:

  • Metal atoms sharing a “sea” of electrons, allowing conductivity.
  • Example: Iron (Fe).

• Molecular Crystals:

  • Molecules held together by intermolecular forces such as hydrogen bonds and van der Waals forces.
  • Example: Ice (H₂O).

Applications of Solid – Crystalline:

• Electronics: Semiconductor crystals like silicon.
• Optics: Crystals used in lasers and lenses.
• Materials Science: Understanding properties like hardness and conductivity.

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