Course Content
Section Name Topic Name 3 Classification of Elements and Periodicity in Properties 3.1 Why do we Need to Classify Elements ? 3.2 Genesis of Periodic Classification 3.3 Modern Periodic Law and the present form of the Periodic Table 3.4 Nomenclature of Elements with Atomic Numbers > 100 3.5 Electronic Configurations of Elements and the Periodic Table 3.6 Electronic Configurations and Types of Elements: s-, p-, d-, f – Blocks 3.7 Periodic Trends in Properties of Elements
Section Name Topic Name 7 Equilibrium 7.1 Equilibrium in Physical Processes 7.2 Equilibrium in Chemical Processes – Dynamic Equilibrium 7.3 Law of Chemical Equilibrium and Equilibrium Constant 7.4 Homogeneous Equilibria 7.5 Heterogeneous Equilibria 7.6 Applications of Equilibrium Constants 7.7 Relationship between Equilibrium Constant K, Reaction Quotient Q and Gibbs Energy G 7.8 Factors Affecting Equilibria 7.9 Ionic Equilibrium in Solution 7.10 Acids, Bases and Salts 7.11 Ionization of Acids and Bases 7.12 Buffer Solutions 7.13 Solubility Equilibria of Sparingly Soluble Salts
Section Name Topic Name 10 The s-Block Elements 10.1 Group 1 Elements: Alkali Metals 10.2 General Characteristics of the Compounds of the Alkali Metals 10.3 Anomalous Properties of Lithium 10.4 Some Important Compounds of Sodium 10.5 Biological Importance of Sodium and Potassium 10.6 Group 2 Elements : Alkaline Earth Metals 10.7 General Characteristics of Compounds of the Alkaline Earth Metals 10.8 Anomalous Behaviour of Beryllium 10.9 Some Important Compounds of Calcium 10.10 Biological Importance of Magnesium and Calcium
Section Name Topic Name 12 Organic Chemistry – Some Basic Principles and Techniques 12.1 General Introduction 12.2 Tetravalence of Carbon: Shapes of Organic Compounds 12.3 Structural Representations of Organic Compounds 12.4 Classification of Organic Compounds 12.5 Nomenclature of Organic Compounds 12.6 Isomerism 12.7 Fundamental Concepts in Organic Reaction Mechanism 12.8 Methods of Purification of Organic Compounds 12.9 Qualitative Analysis of Organic Compounds 12.10 Quantitative Analysis
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About Lesson

Aromatic Compounds ( For Detail Refer Book )

  1. It means aroma (pleasant smell).
  2. They have benzene ring C6 H6 (alternate 3 double bond with no benzene ring).
  3. All with benzene ring is called are called Benzenoid compound and with no benzene ring is called non-benzenoid compound).
(Cn H2n  – 6)

When 2 benzene rings on fused:


Isomerism:  Ortho, Meta and Para isomers are formed. ( See In Book )

Stability and structure of benzene ( See In Book )

  • In benzene the double bonds keep on moving so, the structure showing double bond can be written in either ways. It has no effect on the chemical reactions of benzene.

Or we can say that pi electrons keeps moving i.e. shifting of π electron takes place. Therefore basic structure of Benzene can be written as shown below .The Hybridisation is sp 2.

__                                          ( Benzene )

  • Structure of benzene is planar with sp 2 hybridisation .
  • To see stability we can calculate enthalpy of hydrogenation.

              The difference is resonance energy is:

               i.e. 358.5 – 208.1

               = 150.4 KJ/mol

                               So, we conclude that benzene is more stable than normal alkene.

Huckle rule of Aromatic compounds

It gives criteria of aromaticity that is:

  1. Delocalization of electron.
  2. All aromatic compound should have (4n + 2 ) π electrons , Where n = 2 , 6, 10 , or 14.


Preparation of Benzene

  1. Polymerisation of alkynes: In this the 3 molecules of alkynes undergo polymerisation as shown in presence of iron at temperature approximately 873 K.


  1. Decarboxylation of aromatic acids: The reaction involved is given below.
  1. Reduction of phenol: In this reduction of phenol is carried in presence of zinc on heating as given.
  1. Field craft alkylation – This reaction involves introduction of alkyl group in benzene.

Physical properties of benzene

  1. Existence: Benzene and its homologous (Benzene with side chain) up to 8 C atoms are colourless liquid while higher ones are solid with characterized smell.
  2. Solubility: They are insoluble in water but soluble in organic solvent.
  3. Flammability: They are inflammable and burn with sooty smell.
  4. Melting point and boiling point: It increases with increase in number of carbon atoms in chain.
  5. Nature: They are toxic and carcinogenic in nature.

Chemical properties of benzene

  1. Substitution Reaction – In this hydrogen is going to get substituted by some other group.
  • Halogenation

  The Mechanism involved is electrophilic substitution mechanism.

              Ist step: Formation of electrophile

              2nd step: Attack of electrophile on benzene ring

  • Order of halogenations : For fluorine it is quite fast and also leads to explosion

                                              F>  Cl2>  Br2>  I2

         3rd step: Deprotonation

  • Sulphonation (substitution by SO3 H group)

Nitration (substitution by nitro group)

  • Alkylation (substitution by alkyl group)
  • If we want to get 6 halo product then the following reaction occur.
  1. Addition Reaction: It involves the addition of group or group of atoms to benzene.
  • Hydrogenation
  • Halogenation
  • Addition of ozone molecule
  1. Oxidation Reaction

It can be complete oxidation or oxidation of alkyl chain with mild oxidising agent or strong oxidising agents.

  • Combustion (Complete oxidation)
  • Controlled oxidation in presence of vanadium penta-oxide.
  • Oxidation of alkyl chain

          With mild Oxidising agent

With strong oxidising agent: Etard reaction.

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