Class 9 Chemistry: Chapter 1 - 'Matter Around Us'

Introduction

• **Importance: ** The most important and fundamental chapter. If you understand this, you will start taking an interest in the next chapters and in chemistry.
• **Experience: ** The concepts discussed in the chapter are related to real life.

Topics included in the chapter:

1. What is Matter?
2. Classification of Matter
3. Physical States of Matter
4. Nature and Characteristics of Matter
5. Effect of Temperature and Pressure
6. Evaporation and Burning

Initial Discussion

• Definition:
  • Matter: Any object that has mass and occupies space is called matter.
  • Example: Everything around us in life such as pen, screen, table, chair, etc.
• Every Matter has Mass and Space: For something to be matter, it must have mass and occupy space.

Classification of Matter

1. Physical Classification: Solid, Liquid, Gas
   • Solid: Solid
   • Liquid: Liquid
   • Gas: Gaseous
2. Chemical Classification: Elements, Compounds, Mixture
   • Elements: Single substances like - gold, silver
   • Compounds: Substances made by combining elements like - salt, sugar
   • Mixtures: Mixture of different elements like - jelly bean, solution

Physical States of Matter

1. Continuous Nature: Matter consists of particles.
2. Microscopic Particles: Tiny particles like grains of sand make up matter.
   • Example: Mixing of potassium permanganate crystals in water
   • Percolation Nature: Nature of particles to mix with each other

Nature and Characteristics of Matter

1. Space Between Particles:
   • Example: Explained with the example of water and salt.
2. Constant Motion: Particles are always in motion.
   • Example: Mixing of water and color
3. Attraction: Particles attract each other.
   • Example: Chalk and iron piece

States of Matter

1. Solid: Solid state
   • Some common elements: Gold, Silver, Platinum, etc.
   • Characteristics: Definite shape, high density, non-fluidity
2. Liquid: Liquid state
   • Some common liquids: Water, milk, juice, etc.
   • Characteristics: Takes the shape of the container, fluidity
3. Gas: Gaseous state
   • Some common gases: Oxygen, Carbon dioxide, etc.
   • Characteristics: Expansion, takes the shape of the container, highly compressible

Effect of Temperature and Pressure

• Change: Temperature and pressure can change the state of matter.
• Example: Ice turning to water and water turning to steam

Evaporation

• What is evaporation: The reason for feeling cool in summer – evaporation of sweat.
• Example: Why does it feel cool when spirit is applied to a cloth?
• Why do droplets form on the outside of a glass?

Summary

• Review: Important questions and concepts

Conclusion

• Importance of studying the initial chapter, understanding the basic principles of chemistry, and providing a foundation for future chapters.