Chapter 6: Materials Around Us
Explore the diverse materials used in daily life, learn how to group them based on physical properties, and understand the core concept of matter.
1. Observing Objects Around Us
Every object we use in daily life—notebooks, pens, utensils, clothes, toys—is created using one or more specific substances known as materials[cite: 1]. A material is defined as any substance used to make an object[cite: 1].
Pottery in the Indian subcontinent dates back to 7,000–8,000 years ago in Lahuradewa and Mehrgarh[cite: 1]. By the Harappan Civilisation (2600–1900 BCE), wheel-turned terracotta pottery was baked in kilns and decorated with bright red slips and geometric or animal designs[cite: 1].
2. How to Group Materials?
The method of arranging objects into groups based on common properties (like shape, colour, hardness, or purpose) is called classification[cite: 1].
Same Object, Different Materials
A single object (like a tumbler) can be crafted using completely different materials depending on its purpose[cite: 1]:
Same Material, Different Objects
A single raw material like wood can be transformed into multiple completely distinct items[cite: 1]:
- Furniture: Chairs, Tables, Beds
- Building Materials: Doors, Windows, Beams
- Stationery & Tools: Pencils, Rulers, Wooden Spoons
Multiple Materials in One Object
Complex tools and objects combine properties of different materials to function properly[cite: 1]. For example, a ballpoint pen[cite: 1]:
Interactive Challenge: Test Your Grouping Knowledge
Click on an object below to see which category it belongs to based on material composition:
3. Different Properties of Materials
We choose specific materials to make objects depending on their physical and chemical properties as well as the object's intended function[cite: 1].
3.1 Lustre and Appearance
Interactive DemoMaterials that exhibit a shiny surface are called lustrous materials, which are typically metals (e.g., iron, copper, gold, aluminium)[cite: 1]. Materials without shiny surfaces are non-lustrous (e.g., paper, wood, rubber)[cite: 1].
Freshly cut metal exposes a lustrous, shiny surface[cite: 1].
3.2 Hardness and Softness
Press & TestTest how materials react under compression and scratch force:
Sponge / Wax
Soft MaterialEasily compressed or scratched[cite: 1].
Stone / Iron
Hard MaterialDifficult to compress or scratch[cite: 1].
3.3 Transparency Types
Interactive ViewerToggle between materials to see how much light passes through to the object behind them:
Transparent: Objects can be seen through them clearly (e.g., Glass, Clean Water, Air)[cite: 1].
| Category | Definition | Examples |
|---|---|---|
| Transparent | Objects can be seen through them clearly[cite: 1]. | Glass, clean water, air, cellophane[cite: 1]. |
| Translucent | Objects can be seen through them, but not clearly[cite: 1]. | Butter paper, frosted glass[cite: 1]. |
| Opaque | Objects cannot be seen through them at all[cite: 1]. | Wood, cardboard, metals, brick walls[cite: 1]. |
3.4 Solubility in Water
Lab SimulatorSubstances that dissolve completely in water are soluble[cite: 1]. Substances that do not dissolve even after stirring are insoluble[cite: 1].
Select a substance to stir into the beaker.
Gases like oxygen dissolve in water, which is essential for aquatic plants and animals[cite: 1].
Mix 6 teaspoons of sugar and $\frac{1}{2}$ teaspoon of common salt in 1 litre of boiled and cooled water[cite: 1].
3.5 Mass and Volume
Formula & UnitsMass
Quantifies the amount of matter in an object[cite: 1].
Volume
The space occupied by matter[cite: 1].
$$1\text{ m}^3 = 1000\text{ L}$$[cite: 1]
4. What is Matter?
Anything that occupies space and has mass is called matter[cite: 1]. All materials around us—water, air, stone, wood, food—are forms of matter[cite: 1].
5. Ancient Indian Concept: 20 Gunas in Ayurveda
In Ayurveda (Ashtanga Hridaya), matter and living systems are described using 20 properties (10 pairs of opposites)[cite: 1]:
| Property (Sanskrit) | Meaning | Opposite Property | Meaning |
|---|---|---|---|
| Guru | Heavy | Laghu | Light |
| Manda | Slow | Tikshna | Quick / Fast |
| Hima | Cold | Ushna | Hot |
| Snigdha | Unctuous | Ruksha | Dry |
| Shlakshna | Smooth | Khara | Rough |
| Sandra | Solid | Drava | Liquid |
| Mridu | Soft | Kathina | Hard |
| Sthira | Stable | Khala | Moving / Unstable |
| Sukshma | Subtle / Small | Sthula | Big / Gross |
| Vishada | Non-slimy | Picchhila | Slimy |
Textbook Exercises Solved
1. TREMAT → MATTER: (b) Occupies space and has mass[cite: 1]
2. ULSBELO → SOLUBLE: (d) Mixes completely in water[cite: 1]
3. TNERPASNART → TRANSPARENT: (a) Objects can be seen clearly through it[cite: 1]
4. ERUSTL → LUSTRE: (c) Shiny surface[cite: 1]
(i) Wood is translucent while glass is opaque. — False (Wood is opaque, glass is transparent)[cite: 1]
(ii) Aluminium foil has lustre while an eraser does not. — True[cite: 1]
(iii) Sugar dissolves in water whereas sawdust does not. — True[cite: 1]
(iv) An apple is a matter because it occupies no space and has mass. — False (An apple occupies space and has mass)[cite: 1]
Practice Quiz
Q1. Which of the following is an example of an opaque material?[cite: 1]
Q2. What are the core properties that define matter?[cite: 1]
Chapter Summary
- Objects are made of materials; classification arranges them into categories based on shared properties[cite: 1].
- Properties include appearance (lustre), feel (hardness/softness), transparency, and solubility in water[cite: 1].
- Anything that occupies space and has mass is defined as matter[cite: 1].