Matter in Our Surroundings

Introduction

• Everything in the universe is made up of matter.
• Matter has mass and occupies space.
• Early Indian and Greek philosophers classified matter into five elements: air, earth, fire, sky, and water.
• Modern classification is based on physical properties and chemical nature.

1.1 Physical Nature of Matter

1.1.1 Matter is Made up of Particles

• Two historical views on matter: continuous or particulate.
• Activity 1.1 demonstrates that matter is particulate by dissolving salt/sugar in water.

1.1.2 Size of Particles

• Activity 1.2 illustrates the small size of matter's particles through dilution with potassium permanganate.

1.2 Characteristics of Particles of Matter

1.2.1 Space Between Particles

• Demonstrated by dissolving substances in water.

1.2.2 Particles are Continuously Moving

• Activities 1.3, 1.4, and 1.5 show continuous movement and diffusion properties.

1.2.3 Particles Attract Each Other

• Activities demonstrate that forces of attraction vary among different types of matter.

1.3 States of Matter

1.3.1 Solid State

• Solids have definite shape, boundaries, and volume.
• Examples include rubber bands, sugar, and sponges.

1.3.2 Liquid State

• Liquids have fixed volume but no fixed shape, flow easily and are not rigid.
• Solids, liquids, and gases can diffuse into liquids.

1.3.3 Gaseous State

• Gases are highly compressible, diffuse rapidly, and exert pressure on container walls.

1.4 Can Matter Change its State?

• Matter changes state with temperature and pressure adjustments.

1.4.1 Effect of Temperature

• Experimental observations of ice melting and water boiling.
• Concepts of latent heat of fusion and vaporization explained.

1.4.2 Effect of Pressure

• Pressure can change gas into liquid.
• Sublimation and deposition explained.

1.5 Evaporation

• Evaporation occurs at any temperature below boiling point.
• Factors affecting evaporation include surface area, temperature, humidity, and wind speed.

1.5.1 Cooling Effect of Evaporation

• Evaporation causes cooling by absorbing heat from surroundings.

Key Points

• Matter consists of small particles.
• Exists in three states: solid, liquid, gas.
• Forces of attraction vary among solids, liquids, and gases.
• States are inter-convertible with temperature or pressure changes.
• Sublimation and deposition bypass the liquid state.
• Evaporation and boiling are different phenomena.

Exercises

• Questions and activities to reinforce understanding of concepts.