Learn from School Connect Online in this chapter, we will learn topics like changes from day to night, night to a day, rising and setting of sun and moon, changing of climate, melting of ice, and a lot more. Some changes are quick while others take time. Lets study and explore more of such interesting phenomena in this chapter.
CBSE Class 6 Science Notes Chapter 6 Changes Around Us
The different topics covered in CBSE Class 6 Science Chapter 6 are tabulated below:
| Ex-6.1 | Can All Changes Always Be Reversed? |
| Ex-6.2 | Could There Be Other Ways To Bring A Change? |
Ex. 6.1 – Can All Changes Always Be Reversed?
Changes caused by heating: When an object is heated, it gets affected in one or many possible ways.
- Some objects get hot but do not change in any other way.
- Some objects get hot and also expand in size.
- Some objects get hot and begin to bum.
- Some objects get hot and change their state.
Changes by applying pressure: When we apply force to an object:
- We can change its shape and size.
- Air can be compressed.
- Metals can be hammered into thin sheets.
- Elastic can be stretched.
- Cotton can be spun into thin threads.
Chemical changes: These are the changes in which chemical properties of a substance change, and a new substance is formed. For example, cooking food.
Characteristics of chemical changes:
- Properties of products are different from the properties of reactants.
- Most of the chemical changes are irreversible.
- These changes always result in energy changes.
Physical changes: These are the changes in which only physical property of a substance changes and no new substance is formed.Characteristics of physical changes:
- No new substances are formed.
- Products are identical to the reactants.
- These changes are reversible.
Reversible changes: These are the changes that can be reversed.
For example : stretching of rubber
Irreversible changes: These are the changes which cannot be brought back to its original state.
For example : burning paper
Ex. 6.2 – Could There Be Other Ways To Bring A Change?
Melting: A process in which a solid melts to become a liquid on heating is called melting.
Melting point: A constant temperature at which a solid starts melting. This temperature is called the melting point of that solid.
Freezing: A process in which liquid changes into solid form is called freezing.
Changes: Many changes are taking place around us on their own, e.g., flowers bloom and then wither away. We can also bring a change, e.g., change in the size of a balloon by blowing air in it.
Natural changes: The changes which occur in nature on their own are called natural changes. For example, change of day and night, change of season.
Slow changes: The changes which take longer time to occur are called slow changes. For example, rusting of iron, tooth decay.
Contraction: A process in which an object becomes smaller or shrinks is called contraction.
Evaporation: A process in which liquid changes into vapour is called evaporation.
Expansion: A process in which an object becomes bigger in size, e.g. metals expand on heating.
Separation : The separation of the components of a mixture or an impure substance are carried out with the following purposes :
a. To remove the unuseful or harmful component.
b. To obtain the useful component.
c. To remove impurities for getting a pure sample.
Conclusion :
- Changes happen around us and also within us.
- Some changes are reversible, while some others are irreversible.
- Some changes are physical changes; some are chemical changes.
- Heating causes expansion in a material.
- Cooling causes contraction in a material.
- Gases expand the most and solids expand the least.
- Gases contract the most and solids contract the least.
CBSE Notes for Class 6 Science Free Download for All Chapters
| CBSE Class 6 Science Study Notes | CBSE Class 6 Science Study Notes |
| Food: Where Does It comes from? Class 6 notes – Chapter 1 | The Living Organisms And their Surroundings Class 6 notes – Chapter 9 |
| Component of Food Class 6 notes – Chapter 2 | Motion and Measurement of Distances Class 6 notes – Chapter 10 |
| Fibre to Fabric Class 6 notes – Chapter 3 | Light, Shadows and Reflection Class 6 notes – Chapter 11 |
| Sorting Materials Into Groups Class 6 notes – Chapter 4 | Electricity and Circuits Class 6 notes – Chapter 12 |
| Separation of Substances Class 6 notes – Chapter 5 | Fun with Magnets Class 6 notes – Chapter 13 |
| Changes around Us Class 6 notes – Chapter 6 | Water Class 6 notes – Chapter 14 |
| Getting to Know Plants Class 6 notes – Chapter 7 | Air Around Us Class 6 notes – Chapter 15 |
| Body Movements Class 6 notes – Chapter 8 | Garbage In, Garbage Out Class 6 notes – Chapter 16 |
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