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

Physical Properties of alkanes

  1. Polarity of alkanes: Alkanes are non-polar in nature because of same electro negatives of carbon atoms.
  2. Existence: The force of attraction present in them is Vander wall forces due to which the lower members i.e. C1 to C4 exist as gases, C5 – C7 as liquid and higher ones are solid.
  3. Boiling point: – Because of non-polar character they have low boiling point. The boiling points increase with increase in the number of carbon atoms due to increase in Vander wall forces of attraction. However, with increase in branching the surface area decreases and hence, Vander wall force decreases and hence the boiling point decreases.

For example: CH3 CH2CH2 CH3 butane has more boiling point then 2 methyl propane         

      (d)Melting Point: – It not only depends on mass but also on structure of hydrocarbon.

  • So, alkane with odd number of carbon atom has low melting point
  • Alkane with even number of carbon atoms have high melting point
  • Because they have symmetrical structure, so they fit better in lattice due to this their

               Melting point is high.

         For example: Pentane has low melting point than hexane because hexane has                symmetrical structure.

        (e)Solubility: We know Hydrocarbons are non-polar and we also know like dissolve like

So they are not soluble in H2O but soluble in organic solvents like ether CCl4,

       (f)Density: It is lighter than water. It increases with increase number of C atoms.

Chemical properties of alkanes

We know that on saturated Hydrocarbons are quite less reactive and undergo reaction with difficulty therefore they are called paraffin’s.

The reactions shown by them are given below:

  •  1st Substitution reaction: In this one or more Hydrogen’s are replaced by other atoms.

For example

  • Halogenations– In it the Substitution By halogen X (Cl, F, Br, I) occur

     Order of reactivity:  F> Cl > Br > I

Out of them chlorine shows this reaction to an efficient level.

Chlorination of methane: This reaction occurs in normal light

Hydrocarbons Notes and Solution Class 11 Chemistry
Hydrocarbons Notes and Solution Class 11 Chemistry

It involves Free radical mechanism as shown below:

Hydrocarbons Notes and Solution Class 11 Chemistry
Hydrocarbons Notes and Solution Class 11 Chemistry

If we take comparatively bigger alkane then we get isomers as shown below in example:

  • 2nd Oxidation Reaction: it is the Reaction with oxygen

  This reaction may be may be uncontrolled   or controlled oxidation. If it is combustion reaction than the products are always CO2, H2O, heat and light.

  • If it is Complete combustion : then also the products are CO2,  H2O,  heat and light

  CH4            + O2           à        CO2                  + H2O + Heat

(Methane) Oxygen Gas   Carbon dioxide

  • Incomplete combustion or oxidation :

 CH4            + O2           à        CO                  + H2O + Heat

(Methane) Oxygen Gas   Carbon monoxide

            This CO makes the surface block and called Carbon black or soot.

  • Controlled oxidation – occur in presence of catalyst and on the basis of catalyst the products are formed. Like in presence of Copper alcohol is formed, in presence of molybdenum oxide – aldehyde is formed and in presence of silver oxide –carboxylic acid is formed.
  • 3rd Isomerisation

If we subject alkanes to (anhydrous) Aluminium chloride then isomer of alkane is formed.

4th Aromatization Reaction: In this an Aromatic compounds are found are called (Cyclization)

5th Thermal decomposition or pyrolysis: In this breakdown of bigger alkane into lower  alkanes occur and is called as thermal cracking.

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