Classification of Crystalline Solids
Table: Some characteristics of different types of crystalline solids
| Types of Solid | Constituents | Bonding | Examples | Physical Nature | M.P. | B.P. | Electrical Conductivity |
| Ionic | Positive and negative ions network systematically arranged | Coulombic
| NaCl, KCl, CaO, MgO, LiF, ZnS, BaSO4 and K2SO4 etc. | Hard but brittle | High (≃1000K) | High (≃2000K) | Conductor (in molten state and in aqueous solution) |
| Covalent | Atoms connected in covalent bonds | Electron sharing
| SiO2 (Quartz), SiC, C (diamond), C(graphite) etc. | Hard Hard Hard | Very high (≃4000K) | Very high (≃5000K) | Insulator except graphite |
| Molecular | Polar or non-polar molecules | (i) Molecular interactions (intermolecu-lar forces) (ii) Hydrogen bonding
| I2,S8, P4, CO2, CH4, CCl4 etc.
Starch, sucrose, water, dry ice or drycold (solid CO2) etc. | Soft
Soft | Low (≃300K to 600K)
Low (≃400K) | Low (≃ 450 to 800 K)
Low (≃373K to 500K) | Insulator
Insulator |
| Metallic | Cations in a sea of electrons
| Metallic
| Sodium , Au, Cu, magnesium, metals and alloys | Ductile malleable | High (≃800K to 1000 K) | High (≃1500K to 2000K) | Conductor |
| Atomic | Atoms | London dispersion force | Noble gases | Soft | Very low | Very low | Poor thermal and electrical conductors |
