Showing posts from September, 2021

Classification of Crystalline Solids

What are Crystalline Solids ? We know that solids that have their constituent particles arranged in a definite pattern are called crystalline solids. So, depending upon the nature of these constituent particles, crystalline solids are further classified into four types: 1. Ionic solids 2. Molecular solids 3. Covalent or network solids 4. Metallic solids We will discuss all the above crystalline solids one by one. Classification of Crystalline Solids Following are the classification of crystalline solids: 1. Ionic Solids As the name suggests, crystalline solids that are made up of ions i.e cations and anions are called ionic solids. For example; NaCl is an ionic solid which contains Na⁺ and Cl⁻. These ions are held together by strong electrostatic attraction forces.  Properties of ionic solids Following are some properties of ionic solids: 1. They have high boiling and melting points due to the presence of strong electrostatic forces of attraction. 2. They are bad conductors of

Polystyrene: Definition, Preparation, Properties and Applications

What is Polystyrene ? Polystyrene, also known as Polyvinyl benzene is hard, brilliantly transparent, stiff resin which is produced by the free radical addition polymerization of styrene in the presence of benzoyl peroxide. Polystyrene is non-biodegradable and widely used in the food-service industry as rigid trays, containers, disposable eating plates, bowls, etc. Preparation of Polystyrene Polystyrene is prepared by free radical addition polymerization of styrene in the presence of benzoyl peroxide as a catalyst. Properties of Polystyrene 1. Polystyrene exists in an amorphous state due to the presence of bulky phenyl groups which makes packing of Polystyrene inefficient. 2. Polystyrene is non-polar having a melting point of 240 ℃. 3. Polystyrene is a transparent polymer having a good optical property that allows high transmission of all wavelengths. 4. Polystyrene is hard but brittle due to the chain-shifting effect of the benzene ring. 5. Polystyrene has good insulation properti