CBSE Class 6 Science Revision Notes Chapter 8: A Journey through States of Water

Water exists as ice, liquid water and water vapour, and it changes from one state to another through heating or cooling. Evaporation, condensation, melting and freezing continuously move water through different forms in nature.

Water appears in different forms around us. Ice feels hard and keeps its shape, liquid water flows, and water vapour spreads through the air. These forms may behave differently, but they are three states of the same substance.

These CBSE Class 6 Science Revision Notes Chapter 8 follow the current 2026–27 chapter. Revise how water changes its state, why wet surfaces dry, how droplets form on cold objects, and which conditions affect evaporation. The notes also cover the cooling effect, cloud formation, rain and the complete water cycle.

Key Takeaways

• Three states: Water exists as solid ice, liquid water and gaseous water vapour.
• Evaporation: Liquid water changes into water vapour, even at room temperature.
• Condensation: Water vapour changes into liquid water on contacting a cooler surface.
• Water cycle: Water moves continuously between the Earth’s surface and the atmosphere.

Access Class 6 Science Chapter 8 A Journey through States of Water Notes in 30 Minutes

Revise the chapter in three parts:

• First 10 minutes: Three states of water, evaporation and condensation
• Next 10 minutes: Melting, freezing and factors affecting evaporation
• Final 10 minutes: Cooling effect, clouds, rain and the water cycle

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Ice, Water and Water Vapour in Class 6 Science Chapter 8 Notes

Ice and liquid water look and behave differently. However, they are different states of the same substance.

When an ice cube is kept in a cup, it slowly changes into liquid water. Nothing new is added to it during this change.

Ice and Water Are the Same Substance

Ice has a fixed shape and can be held in the hand. Liquid water flows and takes the shape of its container.

These differences show that one substance can exist in forms with different properties.

Such forms are called states.

Three States of Water

Water commonly exists in three states:

Heating or cooling can change water from one state to another.

Evaporation in A Journey through States of Water Notes

Water sometimes seems to disappear from puddles, wet utensils, clothes and floors.

It has not been destroyed. It changes into water vapour and mixes with the surrounding air.

What Is Evaporation?

The process by which liquid water changes into its vapour state is called evaporation.

Evaporation takes place continuously. It can occur even at room temperature.

Disappearing Water on a Steel Plate

Place a spoonful of water on a steel plate and leave it undisturbed.

The water does not pass through the steel. However, it slowly disappears.

This shows that the water changes into water vapour and enters the air.

Daily-Life Examples of Evaporation

Evaporation occurs when:

• Wet clothes dry
• A mopped floor becomes dry
• Water disappears from puddles
• Sweat dries from the skin
• Water sprinkled on a hot pan disappears
• Hand sanitiser dries after rubbing

Water in a puddle may also seep into the ground. Therefore, both seepage and evaporation may reduce puddle water.

Water Vapour and Steam

Water vapour is the gaseous state of water. It is invisible.

When water is sprinkled on a hot pan, visible steam may appear. Steam contains tiny water droplets formed from some of the water vapour.

Therefore:

• Water vapour is invisible.
• Visible steam contains tiny droplets of liquid water.

Condensation in Class 6 Science Chapter 8 Revision Notes

Water droplets may appear outside a glass containing cold water and ice.

These droplets do not usually come from water seeping through the glass.

What Is Condensation?

The process by which water vapour changes into liquid water is called condensation.

When water vapour in the air touches a cold surface, it cools and forms droplets.

Water Droplets on a Cold Tumbler

A glass tumbler containing cold water and ice develops droplets on its outer surface.

The sequence is:

1. Water vapour is present in the air.
2. The outer surface of the tumbler becomes cold.
3. Water vapour touches the cold surface.
4. It changes into small liquid droplets.
5. Small droplets combine into larger drops.

This is condensation.

How Do We Know Water Does Not Seep Through the Glass?

Mark the water level inside the tumbler.

After some time, droplets may form outside, but the water level inside does not fall noticeably.

This shows that the outer water comes mainly from water vapour in the air.

Other Examples of Condensation

Condensation can be observed as:

• Dew on plants in the morning
• Drops under the lid of a boiling utensil
• Water outside a cold bottle
• Droplets on a bathroom mirror
• Cloud formation in the atmosphere

Properties of the Three States of Water

Ice, liquid water and water vapour differ in shape, flow and ability to spread.

Solid State

Ice retains its shape even when placed in a different container.

It does not flow or spread like liquid water.

Liquid State

Liquid water does not have a fixed shape.

It takes the shape of its container but keeps the same volume. It can flow and spread over a surface.

Gaseous State

Water vapour has no fixed shape.

It spreads through all available space and is present in the air around us.

Changes in the States of Water Notes

Water changes its state when it is heated or cooled.

The four main processes are melting, freezing, evaporation and condensation.

Melting

The change of a solid into a liquid is called melting.

Ice melts into liquid water when it gains heat.

Solid ice → Liquid water

Freezing

The change of a liquid into a solid is called freezing.

Water freezes into ice when it is cooled in a freezer.

Liquid water → Solid ice

Evaporation

The change of liquid water into water vapour is evaporation.

Liquid water → Water vapour

Condensation

The change of water vapour into liquid water is condensation.

Water vapour → Liquid water

Complete State-Change Sequence

Ice --melting→ Water

Water --freezing→ Ice

Water --evaporation→ Water vapour

Water vapour --condensation→ Water

Other Substances That Change State

Water is not the only substance that changes state.

Examples include:

• Wax melts when heated and solidifies when cooled.
• Ghee may become liquid on heating.
• Coconut oil may become solid in winter.

Heating and cooling can therefore change the state of several substances.

Factors Affecting Evaporation

Water does not always evaporate at the same speed.

The rate of evaporation depends on exposed area, temperature, air movement and humidity.

Exposed Surface Area

Water evaporates faster when a larger surface is exposed to air.

Suppose equal amounts of water are placed in:

• A narrow bottle cap
• A wide plate

Water in the plate evaporates faster because more of its surface touches the air.

Temperature and Sunlight

Water evaporates faster at a higher temperature.

Water kept in sunlight disappears sooner than the same amount kept in shade.

This is why wet clothes usually dry faster on a hot sunny day.

Movement of Air

Moving air carries away water vapour near a wet surface.

As air movement increases, evaporation becomes faster.

This is why:

• Clothes dry faster on a windy day.
• A fan helps wet clothes dry.
• Sweat dries faster under a fan.

Humidity

Humidity means the amount of water vapour present in the air.

When humidity is high, the air already contains a large amount of water vapour. It cannot accept water vapour as easily.

Therefore, evaporation becomes slower on humid or rainy days.

Factors Affecting Evaporation Table

Cooling Effect of Evaporation

Evaporation requires energy.

When a liquid evaporates, it takes heat from its surroundings. The surroundings then become cooler.

This is called the cooling effect of evaporation.

Why Does Sweat Cool the Body?

Sweat spreads over the skin and evaporates.

During evaporation, it takes heat from the body. This makes the skin feel cooler.

Moving air speeds up the evaporation of sweat, so a fan increases the cooling effect.

Why Does Sanitiser Feel Cool?

Sanitiser evaporates quickly after being rubbed on the hands.

It takes heat from the skin during evaporation. Therefore, the hands feel cool.

Why Does Water in a Matka Stay Cool?

An earthen pot has tiny pores.

A small amount of water passes through these pores and reaches the outer surface. It then evaporates.

The evaporation takes heat from the pot and the water inside. This keeps the stored water cool.

Surahi

A surahi is a traditional clay water container.

Like a matka, its porous surface allows slow evaporation and keeps water cool during summer.

Pot-in-Pot Cooler

A pot-in-pot cooler can preserve fruits and vegetables without electricity.

It contains:

• A small earthen pot
• A larger earthen pot
• Wet sand between them
• A lid or wet jute covering

Water in the sand evaporates and removes heat. This cools the inner pot.

The sand must remain moist for continued cooling.

Other Examples of Evaporative Cooling

• Sprinkling water on a hot roof
• Sprinkling water on the floor
• Sitting near wet curtains in dry weather
• Blowing air over wet skin

How Do Clouds Form?

Water vapour rises from oceans, lakes, rivers, soil and other wet surfaces.

As it rises higher in the atmosphere, the surrounding air becomes cooler.

Role of Condensation

At a certain height, water vapour cools and condenses into tiny water droplets.

These droplets often form around very small dust particles in the air.

A large collection of tiny floating droplets forms a cloud.

Why Do Clouds Give Rain?

Small water droplets in clouds join together.

They gradually form larger and heavier drops. When the drops become too heavy to remain suspended, they fall as rain.

Under special conditions, water may fall as:

• Rain
• Snow
• Hail

Role of Dust Particles

Dust particles provide surfaces around which water vapour can condense.

Without these tiny particles, cloud droplets would not form as easily.

Water Cycle in Class 6 Science Chapter 8 Summary Notes

The continuous movement of water between the Earth’s surface and the atmosphere is called the water cycle.

It includes evaporation, condensation and the return of water to Earth.

Steps of the Water Cycle

1. The Sun heats water in oceans, rivers, lakes and soil.
2. Liquid water evaporates into water vapour.
3. Water vapour rises into the atmosphere.
4. The air becomes cooler at higher levels.
5. Water vapour condenses around dust particles.
6. Tiny droplets form clouds.
7. Droplets join and become heavier.
8. Water falls as rain, snow or hail.
9. Water collects in rivers, lakes, oceans and the ground.
10. Evaporation begins again.

Water Stored on Earth

Water may be stored in:

• Oceans
• Lakes
• Rivers
• Groundwater
• Snow and ice
• Soil

Most of the Earth’s water is present in oceans. It cannot be used directly for drinking.

Only a small portion is suitable for plants, animals and humans.

Using Water Responsibly

The demand for usable water increases as population rises.

We can protect water by:

• Avoiding unnecessary wastage
• Keeping water bodies clean
• Using only the amount required
• Preventing pollution
• Reusing water where suitable

Water continues to move through the cycle, but usable clean water remains limited.

Evaporation and Condensation Comparison

Class 6 Science Chapter 8 Summary Notes

Important Terms from A Journey through States of Water

State: A form in which a substance exists.

Solid: A state with a fixed shape and volume.

Liquid: A state that flows and takes the shape of its container.

Gas: A state that spreads through available space.

Water vapour: The invisible gaseous state of water.

Evaporation: Conversion of liquid water into water vapour.

Condensation: Conversion of water vapour into liquid water.

Melting: Conversion of a solid into a liquid.

Freezing: Conversion of a liquid into a solid.

Humidity: The amount of water vapour present in the air.

Cooling effect: Cooling caused when an evaporating liquid takes heat from its surroundings.

Water cycle: Continuous circulation of water between Earth and the atmosphere.

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