Q4 The Nature of Solids

• Solids


  Formed when the temperature of a liquid is low and pressure is high - rigid - particles hardly diffuse
• Crystalline Solids


  • Atoms, ions, or molecules are ordered in well-defined arrangements
  • Have flat surfaces and sharp angles
  • Have regular shapes
• Crystalline Solids


  • Ice
  • Sugar
  • Salt
  • Gems
• Amorphous Solids


  • Do not have orderly structures
  • Have poorly defined shapes
• Types of Crystalline Solids


  • Ionic Solids
  • Molecular Solids
  • Covalent Solids
  • Metallic Solids
• Ionic Solids


  • Consist of positive and negative ions
  • Held together by electrostatic attractions
  • Hard, brittle, and poor electrical and thermal conductors
• Ionic Solids


  • NaCl
  • MgCl2
  • Ca(NO3)2
• Molecular Solids


  • Consist of atoms or molecules

  Held together by hydrogen bonds, dipole-dipole forces, and dispersion forces

  Soft, low to moderate high melting point, and poor thermal and electrical conductors
• Molecular Solids


  • Most organic compounds

  CO2

  H2O

  Br2
• Covalent Solids


  • Atoms connected in a network of covalent bonds

  Very hard, very high melting point, and often poor thermal and electrical conductors
• Covalent Solids


  • Diamond (Carbon)

  SiC (silicon carbide)

  Quartz (SIO2)
• Metallic Solids


  • Consist of atoms or molecules

  Held together by metallic bonds

  Soft to hard, low to high melting point, malleable, ductile, good thermal and electrical conductors
• Metallic Solids


  • All metallic elements like Cu, Na, Zn, Fe, Al