L1.3: The Solid State

• •Solids can be either crystalline or amorphous.

  •A crystalline solid has a regular arrangement of particles—atoms, molecules, or ions—with a repeating structure.

  •An amorphous solid has no regular arrangement of its closely packed particles.

  •There are four different types of crystalline solids— ionic, molecular, network, and metallic.
• Solids are divided into two categories:

  • Crystalline solids have well defined shapes due to the orderly arrangement of their particles.
  • Amorphous solids lack orderly arrangement and have poorly defined shapes.
• A crystal is composed of particles packed in an orderly three-dimensional array called the crystal lattice.
• Atomic solids consist of individual atoms held together only by dispersion forces.
• Molecular solids consist of individual molecules held together by various combinations of intermolecular forces.
• Ionic solids consist of a regular array of cations and anions.
• Metallic solids exhibit an organized crystal structure.
• Network Covalent solids consist of atoms covalently bonded together in a three-dimensional network.
• •An ionic solid is composed of oppositely charged ions (NaCl).
• •A molecular solid is composed of individual molecules arranged regularly (H2O).
• •A network solid is composed of a vast number of atoms covalently bonded together (SiO2 ).
• •A metallic solid is a lattice of metal cations surrounded by a cloud of e − that move freely (Cu).
• •Amorphous solids have no regular arrangement of their particles.

  •They can be formed when liquids cool too quickly for regular crystal formation.

  •Very large covalent molecules tend to form amorphous solids, because they can become folded and intertwined.

  •Examples include rubber, glass, and plastic.