Solid State

The Solid State General characteristics of solid state: Definite mass, volume and shape Short intermolecular distances Strong intermolecular forces Fixed lattice positions of the constituent particles Incompressibility and rigidity Classification of the solid state: Crystalline Amorphous (sometimes called pseudo solids or super-cooled liquids) Differences between the crystalline and amorphous solids Crystalline Have definite characteristic geometrical shape Melt at a sharp and characteristic temperature When cut with a sharp edged tool, the newly generated pieces are plain and smooth Have definite and characteristic heat of fusion Are true solids Anisotropic in nature Have long-range order Amorphous Have irregular shape Gradually soften over a range of temperature When cut with a sharp edged tool, the newly generated pieces are with irregular surfaces Do not have definite heat of fusion Are pseudo solids Isotropic in nature Have only short-range order

Classification of crystalline solids (On the basis of the nature of intermolecular forces) Molecular solids Non-polar molecular solids →These consist either atoms or the molecules formed by non-polar covalent bonds. Example: H2 , Cl2 , I 2 Polar molecular solids → The molecules ion these types of solids are held together by strong dipole-dipole interactions. Example: Solid SO 2 , solid NH3

Hydrogen-bonded molecular solids → The molecules of such solids contain polar covalent bonds between H and f, O or N atoms. Example: Ice (H2 O) Ionic solids Ions are the constituent particles; e.g., NaCl, KNO 3 Metallic solids Each metal atom is surrounded by electrons; e.g., Fe, Cu Covalent or network solids Formed by covalent bonds; e.g., diamond, silicon carbide

General characteristics of solid state: Definite mass, volume and shape Short intermolecular distances Strong intermolecular forces Fixed lattice positions of the constituent particles Incompressibility and rigidity Classification of the solid state: Crystalline