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 |