NCERT Solutions for Class 11 Chemistry Chapter 4 - Classification of Elements and Periodicity in Properties

This chapter discusses the valence electrons ionic bond, covalent bond, and bond parameters. The chapter also explains Lewis structure, the covalent bond's polar character, the covalent character of an ionic bond, valence bond theory, resonance, covalent molecules' geometry, and VSEPR theory, and concept of hybridisation involving s, p and d orbitals. The shapes of some simple molecules, the molecular orbital theory of homonuclear diatomic molecules and Hydrogen bond has also been explained.

• Kossel-Lewis Approach to Chemical Bonding

The facts and results obtained through the number of attempts and experiments made to explain a chemical bond's formation in terms of electrons by Kossel and Lewis are explained in this topic. It also introduces students to the discovery of valence electrons, electrovalent bonds, and covalent bonds.

• Lewis Representation of Simple Molecules (the Lewis Structures)

Students learn the Lewis dot structures that provide a picture of bonding in molecules and ions in terms of the shared pairs of electrons and the octet rule.

• Ionic or Electrovalent Bond

This topic discusses the rules that ionic compounds depend on and the formation of ionic bonds.

• Bond Parameters

This topic is a mix of Bond Length, Bond Angle, Bond Enthalpy, Bond Order, Resonance Structures, and Polarity of Bonds. Students learn in detail about these five concepts in this section.

• The Valence Shell Electron Pair Repulsion (VSEPR) Theory

This theory provides a simple procedure to predict the shapes of covalent molecules. It also lists down the main postulates of VSEPR theory and discusses electron pairs' repulsive interaction decrease in the order.

• Valence Bond Theory

The two important theories based on quantum mechanical principles are called valence bond (VB) theory and molecular orbital (MO) theory. For the sake of convenience, the valence bond theory has been discussed in terms of qualitative and non-mathematical treatment only.

• Hybridisation

In order to clearly and easily explain the characteristic geometrical shapes of polyatomic molecules like CH4, NH3 and H2O etc., the concept of hybridisation was introduced. This section also deals with the features and types of hybridisation.

• Hydrogen Bonding

This topic deals with the attractive force that binds the hydrogen atom of one molecule with the electronegative atom (F, O or N) of another molecule, hydrogen bonding.