7.1 periodicity and lattices of crystal structure 7.1.1 The characteristics of crystal structure 1.A few definitions: Solids can be divided into to primary categories, crystalline and amorphous. Crystalline Solids that are built from atoms or molecules arranged in a periodic manner in space. Amorphous Solids posses short range order only. They are not related through symmetry. Short Range Order:Fixed bond lengths and angles Long Range Order:Associated with a lattice point Crystals: Crystals are solids that are built from atoms or molecules arranged in a periodic manner in space. Crystalline vs.Amorphous of SiO2 Quartz:(Crystalline) Glass:(Amorphous) Both Short and Long Range Order Short Range Order Only Oxygen Silicon7.1 periodicity and lattices of crystal structure 7.1.1 The characteristics of crystal structure 1. A few definitions: • Solids can be divided into to primary categories, crystalline and amorphous. • Crystalline Solids that are built from atoms or molecules arranged in a periodic manner in space. • Amorphous Solids posses short range order only. They are not related through symmetry. • Short Range Order: Fixed bond lengths and angles • Long Range Order: Associated with a lattice point Crystals: Crystals: Crystals are solids that are built from atoms or Crystals are solids that are built from atoms or molecules arranged in a periodic manner in space. molecules arranged in a periodic manner in space