Objects & Materials
Everything is made of materials!
Appearance & Lustre
Shiny vs. Dull surfaces
Solubility
What dissolves & what doesn't
Concept of Matter
Mass & Volume explained simply
1. Objects and Materials around Us
What is an Object?
An object is anything that we can see, touch, or feel around us. Examples: notebook, water bottle, chair, toy, spoon.
What is a Material?
A material is the stuff or substance that is used to make an object.
| Object | Materials it can be made of |
|---|---|
| Tumbler / Cup | Glass, Plastic, Stainless Steel, Clay |
| Chair | Wood, Iron, Plastic, Bamboo |
| Toys | Plastic, Wood, Cloth, Rubber, Metal |
2. Grouping of Materials (Classification)
What is Grouping?
Placing or arranging things together based on their similarities and differences is called Grouping or Classification.
Why do we need Grouping?
• Convenience: It helps us locate items easily (like finding spices grouped together in a kitchen or books in a library).
• Easy Study: It allows us to study the properties of whole groups easily instead of studying each item one by one.
3. Appearance: Lustre and Texture
Shiny vs Dull (Lustre)
• Lustre: The shiny appearance on the freshly cut or clean surface of a material is called lustre.
• Lustrous Materials: Materials that shine brightly. Examples: Copper, Aluminium, Gold, Silver, Iron.
• Non-Lustrous Materials: Materials that look dull and do not shine. Examples: Wood, Paper, Rubber, Chalk, Eraser.
Hardness and Texture (Touch)
• Hard Materials: Materials that are difficult to compress, bend, or scratch easily. Examples: Iron, Stone, Glass, Brick.
• Soft Materials: Materials that can be easily compressed, cut, or scratched. Examples: Cotton, Sponge, Rubber ball, Butter.
4. Transparency (Light Passing Capacity)
Based on whether light can pass through them, materials are divided into 3 types:
| Property | Meaning / Definition | Daily Life Examples |
|---|---|---|
| Transparent | Substances through which light passes completely and objects can be seen clearly. | Clear glass, Pure water, Air, Clear plastic sheets. |
| Translucent | Substances through which light passes partially and objects can be seen partially / blurrily. | Butter paper, Oiled paper, Frosted glass, Buttercloth. |
| Opaque | Substances through which light cannot pass at all and objects cannot be seen at all. | Wood, Cardboard, Metal sheet, Brick wall. |
5. Solubility in Water (Soluble vs Insoluble)
Soluble Substances
Substances that mix or dissolve completely in water and disappear are called Soluble.
Examples: Salt, Sugar, Glucose powder, Lemon juice, Vinegar.
Insoluble Substances
Substances that do not mix or dissolve in water, even after stirring for a long time, are called Insoluble.
Examples: Sand, Sawdust, Chalk powder, Mustard oil, Kerosene, Wheat flour.
Do Gases Dissolve in Water?
• Yes! Some gases like Oxygen gas are dissolved in water. Fish and aquatic plants use this dissolved oxygen to live underwater.
6. Floating and Sinking in Water
Floating Objects
Objects that stay on the surface of water because they are lighter than water.
Examples: Dry leaf, Plastic ball, Wooden block, Feather, Cork, Thermocol.
Sinking Objects
Objects that sink to the bottom of the water container because they are heavier than water.
Examples: Iron nail, Stone, Coin, Glass marble, Keys.
7. Mass, Volume, and What is Matter?
1. What is Mass?
• The amount of matter or content contained in an object is called its Mass.
• It tells us how heavy or light an object is.
• Unit: Measured in grams (g) or kilograms (kg) using a balance scale.
2. What is Volume?
• The amount of 3D space occupied by an object is called its Volume.
• Example: A big football occupies more volume (space) than a small marble.
• Unit: Measured in Liters (L), Milliliters (mL), or cubic centimeters ($cm^3$).
3. Definition of MATTER (Super Important!)
Anything that has mass and occupies space (volume) is called MATTER.
• Everything around us — air, water, books, trees, animals, chairs, and even humans — is made up of matter!
Quick Vocabulary Flashcards (Click to Flip)
Lustre
Tap to see definitionTranslucent
Tap to see definitionMatter
Tap to see definitionInsoluble
Tap to see definitionChapter 6 Interactive Quiz
Test your knowledge in 1 minute!
1. Which of the following materials possesses lustre (shine)?
2. Butter paper is an example of which type of material?
3. Which substance is completely SOLUBLE in water?
4. Anything that has mass and occupies space is defined as: