Explain how thermal conductivity relates to the following: (a) bond type (ionic, covalent, metallic bonds), (b) interatomic distance, bond strength, and melting point, (c) structure density, (d) simple and complex structures, (e) amorphous and crystalline solids (insulators), (f) layer structures and chain structures, (g) crystalline solution (solid solution) and defects, (h) grain boundary, porosity, and microcracks.