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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Mendeléev’s periodic table ( Classification of Elements )

  • In Mendeléev’s periodic table only 63 elements were arranged that were examined on the basis of the relationship between the atomic masses of elements
    and their physical and chemical properties.
  • Hydrogen and oxygen were selected due to their high reactivity and formation of compounds with most elements giving rise to hydrides and oxides that were treated as one of the basic properties of an element.
  • Properties of 63 elements were written on 63 cards and then the elements with similar properties were sorted.
  • Most of the elements were arranged in the order of their increasing atomic masses in the Periodic Table with the occurrence of periodic recurrence of elements with similar physical and chemical properties.
  • As per the arrangement of elements Mendeléev formulated a Periodic Law stated as ‘the properties of elements are the periodic function of their atomic masses’.
  • The Periodic Table consists of vertical columns termed as ‘groups’ and horizontal rows termed as ‘periods’.
NCERT Solutions for Class 11 Chemistry Chapter 3 Classification of Elements and Periodicity in Properties. Class 11 Chemistry Notes

Achievements of Mendeléev’s periodic table ( Classification of Elements )

  • element with a slightly greater atomic mass were placed
    before an element with a slightly lower atomic mass with an inverted sequence so as to group the elements with similar properties. For example, cobalt with atomic mass 58.9 was placed before nickel with atomic mass 58.7.
  • He left some gaps in the Periodic Table with the prediction of
    existence of some elements that were not discovered at that time.
  • He named the future elements by prefixing a Sanskrit numeral, Eka (one) to the name of preceding element in the same group.
  • For instance, scandium, gallium and germanium, discovered later, have properties
    similar to Eka–boron, Eka–aluminium and Eka–silicon, respectively.
  • Noble gases like helium (He), neon (Ne) and argon (Ar) were discovered
    later as they are present in exceptionally low concentrations in the atmosphere due to their inertness.

NCERT Solutions for Class 11 Chemistry Chapter 3 Classification of Elements and Periodicity in Properties. Class 11 Chemistry Notes


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