1. Molecular Solid
2. Ionic Solid
3. Metallic Solid
4. Covalent or Network, Insulator
Unit cell is the smallest portion of a crystal lattice which, when repeated in different directions, generates the entire lattice.
Atoms are arranged at all corners of cube.
Atoms are at all corners & at body center of cube.
Sphere of III layer occupy those voids of II layer under which there are sphere of Ist layer. So third layer is exactly identical to Ist layer.
Hexagonal Packing Efficiency
(1) NaCl type of structure (Rock salt structure) :
(i) Cl– ions form the FCC lattice while Na+ ion occupy all the octahedral void.
Zn2+ ion occupy alternate (non adjacent) four tetrahedral void.
Cl– form simple cubic lattice.
In crystal lattice of diamond, carbon atoms adopt FCC arrangement with occupancy of 50% tetrahedral voids.
(a) Schottkey , (b) Frenkel , (c) Interstitial
(i) Electrical Properties
(ii) Magnetic Properties