NCERT Solutions for Class 12 Chemistry, Chapter 1 - The Solid State

In the previous classes, we have learnt about the states of matter available in nature. Chemistry- the branch of science associated with the substances with which matter is composed- has helped us understand the three states easily found, i.e. the Solid State, Liquid State and the Gaseous State. We also know about the process of transition from one state to another. In the NCERT Chemistry Class 12 Chapter 1 – The Solid State, we shall learn about the further classifications of the solid-state, the amorphous state and the crystalline state. The chapter will shed light on the classifications based on the nature of the intermolecular forces operating between them- molecular, ionic, metallic or covalent. We shall also learn about their physical characteristics and properties. The chapter helps us to understand about Crystal Lattice and the packing structures.

The crystal lattice is generally referred to the regular array of structures (atoms/ions/molecules) inside the crystalline structure. We shall know about unit cell- the smallest part of the crystal lattice, which can be repeated in all directions to generate crystal lattice. There are 14 different possible types of lattices which are collectively called Bravais Lattices. Based on the position of the particles- the unit cells can be either primitive(positioned at the corner) or body-centred (extra particles are positioned at the centre).

Closed-packing of the particles results in 2 highly efficient packing systems- hexagonal closed packing system (HCP) and the cubic-closed packing(CCP). CCP is also known as Face-Centred Cubic Lattice. Both are 74% efficient. There are two types of empty spaces present: Octahedral Void and Tetrahedral Voids. Other forms of packings are less efficient. For example, Body Centred Cubic (BCC) lattice has 68% filled space while Simple Cubic Cell – 52.4 % space is filled.

Solids, though compact in shape and structure, often have minute defects in their molecular or crystalline structure. The defects, either Point or Interstitial, are elaborated and covered in the chapter. The Point defects are further categorised into Stoichiometric Defects, Impurity Defects and Non-Stoichiometric Defects. In the case of ionic solids, they are known as Frenkel or Schottky Defects. Impurity defects are caused due to the presence of impure particles in the crystal. Doping of semiconductors is a process where impurities are added in semiconductors to change their electrical properties.

Solids also exhibit various magnetic properties such as Paramagnetism, Diamagnetism, Ferromagnetism, Antiferromagnetism and Ferromagnetism. These properties are what makes them useful in various sorts of audio, video and other recording devices.

Let’s take a look through the topics and sub-topics of the chapter:

1. The Solid State.

2. General characteristics of Solid State.

3. Amorphous and Crystalline Solids.

4. Classification of Crystalline Solids.

5. Crystal Lattices and Unit Cells.

6. Number of Atoms in a Unit Cell.

7. Close Packed Structures.

8. Packing Efficiency.

9. Calculations involving Unit Cell Dimensions.

10. Imperfections in Solids.

11. Electrical Properties.

12. Magnetic Properties.

In this chapter, you are provided with several examples along with their solutions for a clear understanding of facts and concepts. To know more about NCERT Chemistry Class 12 Exercise Questions Solutions Chapter 1, you should explore the exercises below. You can also download the NCERT Class 12 The Solid State Solutions PDF, solved by teachers and experts.