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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Ionization Enthalpy and Hydration Enthalpy of alkali metals

  • Ionization energy is the quantity of energy required to remove loosely bound electron from an atom.
  • Down the group ionization enthalpies of alkali metals decreases.
Class 11 Chemistry Chapter 10 The s-Block Elements Notes and NCERT Solution
The s-Block Elements
  • Increase in atomic number increases the size of the element which in turn outweighs increasing nuclear charge. Therefore the outermost electron experiences strong screening effect from the nuclear charge.
  • The energy released as a result of the formation of new bonds between ions and water molecules is called hydration enthalpy.
  • In alkali metals the hydration enthalpies decreases with the increase in ionic sizes.
    Li+> Na+ > K+ > Rb+ > Cs+
Class 11 Chemistry Chapter 10 The s-Block Elements Notes and NCERT Solution
The s-Block Elements

Chemical Properties of alkali metals

(i) Reactivity towards air

Alkali metals get tarnished in the presence of dry air due to the formation of their respective oxides.

The metallic oxide so formed further reacts with moisture to form hydroxides.

The alkali metals burn vigorously in oxygen and form their respective oxides.

4Li + O2 –> 2Li2O (Oxide)

 (ii) Reactivity towards water:

The alkali metals react with water and forms hydroxide and dihydrogen.

Class 11 Chemistry Chapter 10 The s-Block Elements Notes and NCERT Solution
The s-Block Elements
Class 11 Chemistry Chapter 10 The s-Block Elements Notes and NCERT Solution

Anomalous properties of lithium

Anomalous behaviour of an element refers to the deviation of the properties and behaviour of an element from its usual or normal behaviour.

 It is due to the following reasons:

(i) Exceptionally small size of its atom and ion

(ii) High polarizing power

The anomalous behaviour of lithium is as follows:

  • Lithium is harder than other metals of the respective group.
  • It has higher Melting and boiling point than other metals
  • It is least reactive.
  • It is strongestreducing agent.
  • Unlike other metals LiCl is deliquescent and exist as LiCl.2H2
  • Li+ ion polarizes water molecules readily than other alkali metals of the respective group and hence the lithium salts attracts the water molecules and it exists as water of crystallization (2H2O). As the polarizing power decreases with the increasing size of the ions the other alkali metal ions usually form anhydrous salts.
  • Lithium does not form ethynide on reacting with Ethyne.
  • Heating lithium nitrate results in the production of lithium oxide, Li2

4LiNO3 –> 2Li2O + 4NO2 + O2

Lithium nitrate          Lithium oxide

  • Heating nitrates of other alkali metal results in the decomposition of the nitrate leading to the production of their corresponding nitrite.

2NaNO3 –> 2NaNO2 + O2

Sodium nitrate                  Sodium nitrite

Class 11 Chemistry Chapter 10 The s-Block Elements Notes and NCERT Solution
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