Paulings three rules governing the structure of ionic compounds 1. Anion Coordination polyhedron rule Each cation is surrounded by an anion polyhedron, the distance between anion and cation is r=rt tr, while the cn depends on rt/r

1. The structure of am b differs from those of either a or B 2. Its composition is variable to more or lessextension 3. Mixed bonding 4. Intermediate properties

1. Sing le crystal ver sus po l crystal 1. For single crystals there is only one type of structure with same orientation Single crystals is characterized by anisotropy 2. Polycrystal consists of a lot of grain, small single crystals, With same structure but different orientations. These small single crystals are called grains. The boundaries between them are called grain boundaries

3. 1 Basic concepts of al loys 1. Definition An alloy is the combination of metal(s) with other elements through chemical bonding. Termino logy

2.7 Some Important Crystallographic Formulas 1. Zone and zone equation All Planes parellel to common axis [uvw] constitute a (crystal) zone, the [u v w] zone. If (h k l) belongs to zone [u v w], then hukv+=0 2.ifhuk+hw=0,then[uvw] lies in(hk) 3. For cubic crystals, [h (h k)

2. Classification of materials based on structure Regularity in atom arrangement periodic or not (amorphous)

2.5 Indices of crystal planes and directions I What's crystal planes anddirect ions? The atomic planes anddirections passing through the crystal arecalled(crystal) planes and directionsrespectively

2.3 Crystal Structure and Complex Lattice | Crystal structure is the real arrangement of atom in crystals Crystal structure Space lattice Basis or structure unit

1.2 Atomic bonding Bonding forces and energies FF net force attractive force repulsive force

Chapter 1 Atomic Structure and Bonding 1.1 Atomic structure Atomic numbers and atomic masses 1. Atomic Models