The Solid State

General Characteristics of Solid State

(i)   They have definite mass, volume and shape.

(ii)  Inter molecular distance are short

(iii) Inter molecular forces are strong

(iv) Their constituent particles (atoms, molecules or ions) have fixed positions and can only oscillate about their mean positions

(v) They are incompressible and rigid

Solids can be classified as crystalline or amorphous on the basis of the nature of order present in the arrangement of their constituent particles.

Property	Crystalline Solids	Amorphous Solids
Shape	Definite characteristic geometrical shape.	Irregular shape.
Melting Point	Melt at a sharp and characteristic temperature	Gradually soften over a range of temperature
Cleavage Property	When cut with a sharp edged tool, they split into two pieces and the newly generated surfaces are plain and smooth	When cut with a sharp edged tool, they cut into two pieces with irregular surfaces
Heat of Fusion	They have a definite and characteristic heat of fusion	They do not have definite heat of fusion
Anisotropy	Anisotropic in nature	Isotropic in nature
Nature	True solids	Pseudo solid or super cooled liquids
Order in arrangement of constituent particles	Long range order	Only short range order

Examples

Sodium chloride and Quartz

Glass, Rubber and plastics

Classification of crystalline solids

1) Molecular solids

(i) Non polar :- Dispersion or London force | Ar , CCl4 , H2 , I2 , CO2

(ii) Polar :- Dipole-dipole interactions | HCl , SO2

(iii) Hydrogen bonded :- Hydrogen bonding | H2O (ice)

2) Ionic solids :- Coulombic or electrostatics | NaCl , MgO , ZnS , CaF2

3) Metallic solids :- Metallic bonding | Fe , Cu , Ag , Mg

4) Covalent or network solids :- Covalent bonding | SiO2(quartz) , SiC , C(diamond,graphite) ,Hard Insulators Very high AIN

Crystal Lattices 

A regular three dimensional arrangement of points in space

Bravais Lattices 

There are only 14 possible three dimensional lattices.These are called Bravais Lattices

Lattice Point or Lattice Site

Each point in a lattice is called Lattice Point or Lattice Site