Q:
What are the Definitions of
the Five Levels of Structure?




A:
  • Electronic/Bonding Structure: The number
    and manner in which the outer shell (valence)
    electrons are employed to form bonds.
    - As an example, silicon (atomic number = 14)
       has 4 valence electrons.



  • Atomic/Molecular Structure: The nature
    of the atoms/molecules/monomers that
    constitute the building blocks of the material.

    - For example, the "silica monomer" consists
    of a single silicon atom, which is tetrahedrally
    bonded to four oxygen atoms. The oxygen atoms
    themselves are bonded to two silicon atoms.



  • Crystal Structure: The periodic arrangement
    of atoms/molecules/monomers in space. Silica is
    polymorphic:

    - Tridymite has a hexagonal crystal structure
    - Cristobalite has a cubic crystal structure
    - Silica glass is amorphous.


  • However, all forms of silica (including Quartz)
    have the same monomeric structure.



  • Microstructure: The size and distribution
    of individual grains/phases/defects in a material.

    - As an example, the microstructure of Sandstone consists
      of quartz grains in a calcite matrix.



  • Macrostructure: The shape/size of the body
    e.g., the "cut" of an amethyst (quartz) gemstone.