Title 2nd chem ch 01.pdf ✅

Chapter 1 The Solid State • They are anisotropic in nature i.e. their physical properties show different values when measured along different directions in the same crystal. • They have a definite and characteristic heat of fusion. • They are called true solids. • When cut with a sharp edged tool , they split into two pieces and the newly generated surfaces are plain and smooth. Polymorphic forms or polymorphs: The different crystalline forms of a substance are known as polymorphic forms or polymorphs .For example: graphite and diamond. Characteristics of amorphous solids: 1. They have an irregular shape. 2. They have a short range order. 3. They gradually soften over arrange of temperature. 4. They are isotropic in nature i.e. their physical properties are the same in all directions. 5. When cut with a sharp edged tool, they cut into two pieces with irregular surfaces. 6. They do not have definite heat of fusion. 7. They are called pseudo solids or super cooled liquids. This is because they have a tendency to flow,though very slowly.
Chapter 1 The Solid State Types of crystalline solids: A. Molecular Solids Constituent Particles: Molecules Constituent Particles: IonsB. Ionic Solids Bonding/Attractive Forces: Coulombic or Electrostatic Electrical Conductivity: Insulators in solid state but conducts in molten state and in aqueous solutions Physical Nature: Hard but brittle Melting Point: High Examples: , ZnS, MgO, NaCl C. Metallic Solids Constituent Particles:Positive ions in a sea of delocalized electrons Bonding/Attractive Forces: Metallic bonding Electrical Conductivity: Conductors in solid state as well as in molten state Physical Nature: Hard but malleable and ductile Melting Point: Fairly high Examples: Fe ,Cu, Ag, Mg D. Covalent or NetworkSolids Constituent Particles:Atoms Bonding/Attractive Forces: Covalent bonding Electrical Conductivity: Conductors in solid state as well as in molten state Physical Nature: Hard but malleable and ductile Melting Point: Fairly high