CBSE CLASS 12
CHEMISTRY
Complete Chapter Notes
Chapters 1, 2 & 3
The Solid State | Solutions | Electrochemistry
WHAT'S INSIDE
✓ Complete theory with crystal-clear explanations
✓ All important formulas with derivations
✓ Exam-focused short notes & memory tricks
✓ NCERT exemplar problems solved
✓ Previous year questions (PYQs) with solutions
✓ Quick revision tables & comparison charts
✓ Important definitions & key terms
✓ Numerical problem-solving strategies
2026 Edition | For CBSE Board Exams & Competitive Exams
JEE Mains | NEET | State Board Exams
, TABLE OF CONTENTS
CHAPTER 1: THE SOLID STATE 3
1.1 General Characteristics of Solids 3
1.2 Classification of Crystalline Solids 4
1.3 Crystal Lattices & Unit Cells 6
1.4 Number of Atoms in a Unit Cell 7
1.5 Close-Packed Structures 9
1.6 Packing Efficiency 11
1.7 Calculations Involving Unit Cell Dimensions 12
1.8 Imperfections in Solids 13
1.9 Electrical & Magnetic Properties 15
1.10 Quick Revision & PYQs 17
CHAPTER 2: SOLUTIONS 19
2.1 Types of Solutions 19
2.2 Expressing Concentration 20
2.3 Solubility & Henry's Law 22
2.4 Vapour Pressure of Liquid Solutions 24
2.5 Raoult's Law 25
2.6 Ideal & Non-Ideal Solutions 27
2.7 Colligative Properties 29
2.8 Abnormal Molar Masses 33
2.9 Quick Revision & PYQs 35
CHAPTER 3: ELECTROCHEMISTRY 37
3.1 Electrochemical Cells 37
3.2 Galvanic Cells 38
3.3 Nernst Equation 40
3.4 Conductance of Electrolytic Solutions 42
,3.5 Kohlrausch's Law 44
3.6 Electrolysis & Faraday's Laws 46
3.7 Batteries & Fuel Cells 48
3.8 Corrosion 50
3.9 Quick Revision & PYQs 51
, CHAPTER 1
THE SOLID STATE
CHAPTER OVERVIEW
This chapter deals with the study of solids — their structure, classification, and properties. It forms the
foundation for understanding materials science and is crucial for both board exams and competitive exams
like JEE and NEET. Weightage: 4–6 marks in CBSE Boards.
Key Topics: Classification of solids, unit cells, packing efficiency, defects, electrical & magnetic properties
1.1 GENERAL CHARACTERISTICS OF SOLIDS
Definite Shape & Volume: Solids have fixed shape and volume due to strong intermolecular forces of
attraction. The constituent particles (atoms, ions, or molecules) are held together by strong forces and have
fixed positions.
High Density: Particles are closely packed, resulting in high density compared to liquids and gases.
Incompressibility: Solids are nearly incompressible because there is very little free space between
particles.
Rigidity: Solids resist change in shape. They can only undergo elastic deformation under stress.
Slow Diffusion: Diffusion in solids is extremely slow because particles have very little freedom of
movement.
■ MEMORY TRICK: Remember SIDRI — Shape fixed, Incompressible, Dense, Rigid, diffusion is
Impossibly slow
Property Solid Liquid Gas
Shape Fixed Takes shape of container No fixed shape
Volume Fixed Fixed Takes volume of container
Density High Moderate Low
Compressibility Negligible Very low High
Intermolecular forces Very strong Moderate Negligible
Particle arrangement Ordered (crystalline) or disordered
Disordered(amorphous)
but close Random, far apart
Diffusion Extremely slow Slow Fast
1.2 CLASSIFICATION OF CRYSTALLINE SOLIDS
Solids are classified into two main categories based on the arrangement of constituent particles:
CHEMISTRY
Complete Chapter Notes
Chapters 1, 2 & 3
The Solid State | Solutions | Electrochemistry
WHAT'S INSIDE
✓ Complete theory with crystal-clear explanations
✓ All important formulas with derivations
✓ Exam-focused short notes & memory tricks
✓ NCERT exemplar problems solved
✓ Previous year questions (PYQs) with solutions
✓ Quick revision tables & comparison charts
✓ Important definitions & key terms
✓ Numerical problem-solving strategies
2026 Edition | For CBSE Board Exams & Competitive Exams
JEE Mains | NEET | State Board Exams
, TABLE OF CONTENTS
CHAPTER 1: THE SOLID STATE 3
1.1 General Characteristics of Solids 3
1.2 Classification of Crystalline Solids 4
1.3 Crystal Lattices & Unit Cells 6
1.4 Number of Atoms in a Unit Cell 7
1.5 Close-Packed Structures 9
1.6 Packing Efficiency 11
1.7 Calculations Involving Unit Cell Dimensions 12
1.8 Imperfections in Solids 13
1.9 Electrical & Magnetic Properties 15
1.10 Quick Revision & PYQs 17
CHAPTER 2: SOLUTIONS 19
2.1 Types of Solutions 19
2.2 Expressing Concentration 20
2.3 Solubility & Henry's Law 22
2.4 Vapour Pressure of Liquid Solutions 24
2.5 Raoult's Law 25
2.6 Ideal & Non-Ideal Solutions 27
2.7 Colligative Properties 29
2.8 Abnormal Molar Masses 33
2.9 Quick Revision & PYQs 35
CHAPTER 3: ELECTROCHEMISTRY 37
3.1 Electrochemical Cells 37
3.2 Galvanic Cells 38
3.3 Nernst Equation 40
3.4 Conductance of Electrolytic Solutions 42
,3.5 Kohlrausch's Law 44
3.6 Electrolysis & Faraday's Laws 46
3.7 Batteries & Fuel Cells 48
3.8 Corrosion 50
3.9 Quick Revision & PYQs 51
, CHAPTER 1
THE SOLID STATE
CHAPTER OVERVIEW
This chapter deals with the study of solids — their structure, classification, and properties. It forms the
foundation for understanding materials science and is crucial for both board exams and competitive exams
like JEE and NEET. Weightage: 4–6 marks in CBSE Boards.
Key Topics: Classification of solids, unit cells, packing efficiency, defects, electrical & magnetic properties
1.1 GENERAL CHARACTERISTICS OF SOLIDS
Definite Shape & Volume: Solids have fixed shape and volume due to strong intermolecular forces of
attraction. The constituent particles (atoms, ions, or molecules) are held together by strong forces and have
fixed positions.
High Density: Particles are closely packed, resulting in high density compared to liquids and gases.
Incompressibility: Solids are nearly incompressible because there is very little free space between
particles.
Rigidity: Solids resist change in shape. They can only undergo elastic deformation under stress.
Slow Diffusion: Diffusion in solids is extremely slow because particles have very little freedom of
movement.
■ MEMORY TRICK: Remember SIDRI — Shape fixed, Incompressible, Dense, Rigid, diffusion is
Impossibly slow
Property Solid Liquid Gas
Shape Fixed Takes shape of container No fixed shape
Volume Fixed Fixed Takes volume of container
Density High Moderate Low
Compressibility Negligible Very low High
Intermolecular forces Very strong Moderate Negligible
Particle arrangement Ordered (crystalline) or disordered
Disordered(amorphous)
but close Random, far apart
Diffusion Extremely slow Slow Fast
1.2 CLASSIFICATION OF CRYSTALLINE SOLIDS
Solids are classified into two main categories based on the arrangement of constituent particles:
