http://www.vkscience.com: SORTING MATERIALS INTO GROUPS CLASS VI CHAPTER IV

Introduction-

We see a number of things around us. These can be classified into natural, man-made, solid, liquid, gases, lustrous, non-lustrous, opaque, transparent, translucent etc.

In our home, school, library, kitchen etc. we classify the objects into different categories. The process of grouping of objects based on their known properties is called classification.

Materials around Us-

Different kinds of materials are made up of may form any object. Also, different objects can be can be made from same material.

Same material forming different objects (Products)

Material	Objects (Products)
Wood	Chair, Table, Wheel, Plough
Paper	Book, Notebook, Newspaper, Toys
Leather	Shoes, belt, Jacket
Plastic	Toys, Bucket, Tumbler

Different materials forming one object (Product)

Materials	Object
Plastic, Paper, Steel, Wood, Soil	Plate (Thali)
Plastic, Metal, Wood	Pen
Wood, Plastic, Metal	Door
Glass, Plastic, Gold, Silver	Bangle

Natural and Man-made materials-

Those materials which are made in nature are called as natural materials.

e. g- Cotton, Wood, Gold, Coal, Rocks etc.

Those materials and objects which are made by humans are called as artificial or man-made or synthetic materials. E.g.-Furniture, Books, Cars, Clothes, Trains, Ornaments etc.

Properties of Materials-

We choose any object/product on the basis of their properties and uses.

The important properties of the objects can be –

1. Appearance-The metallic objects and objects made up of alloy shine (lusture). They reflect the light falling on them. But due to rusting sometimes they may appear dull. e. g.- Objects of Gold, Silver , Iron, Brass, Bronze etc.

Non-metals do not shine as like metals. They usually have rough surface. e. g.- Clothes, Notebooks, Leather, wood products etc. Except- Diamond. Diamonds actually do not shine. Diamonds are made shining and glittering by cutting and polishing.

2. Hardness- Many objects can be hard or soft. Hard objects are difficult to be compressed or scratch. e. g- Metal Spoon, Locks and Key, Candle, etc.

Many other objects can be compressed or scratched easily. These are soft objects. e.g.- Cotton and Sponge

3. Solubility- Many substances get dissolved in water. They are called as soluble substances. e. g.- Sugar, Salt, Copper sulphate etc.

Sugar (Solute) + Water (Solvent) = Solution

Some others do not get dissolved in water or other liquids. They are called as insoluble substances. e.g.- Sand, Soil, Chalk, etc.

Those liquids which get mixed with each other are called miscible liquids.

e.g.- Water and Vinegar, Water and Lemon Juice

Those liquids which do not get mixed with each other are called immiscible liquids.

e.g.- Water and Kerosene, Water and Ghee

4. Floating or Sinking Materials- The density of any material decides that the given object will float or sink in the water.

Objects lighter than water will float. e. g.- A dry leaf, Wooden piece, cork etc.

Objects lighter than water will float. e. g.-A coin, an iron nail, rock piece etc.

5. Transparency- The property of objects which allow the light to pass, partially pass or not pass through it is called as transparency.

There are three types of objects on the basis of transparency.

A. Transparent objects- Light can pass through them. e. g. Clear glass, Water, Air

All Light Passes through transparent objects.

B. Translucent Objects- Light can partially pass through the. e.g.- Muddy water, Smoke, Smoky Glass, Sun glass, Butter paper, Oiled paper etc.

Some Light Passes through translucent objects.

C. Opaque Objects- Light cannot pass through them. e. g- Stone, Rock, Wood, Metal, Bricks etc.

No Light Passes through opaque objects.

6. Malleability- The property of metals by which they can be beaten into thin sheet/foil is called malleability. Such metals are called malleable. e.g.- Gold, Iron, Aluminium etc.

7. Ductility- The property of metals by which they can be drawn into thin wires is called ductility. Such metals are called ductile. e.g.- Aluminium, Copper, Iron etc.

8. Conductivity- The property of materials by which they allow the heat and current to pass through them is called conductivity. Such materials are called as conductors. e.g.- Objects of metals like Iron, Copper, Silver, Zinc etc.

Non-conductors (insulators) do not allow the heat and current to pass through them. e.g.- Wood, Clothes, Rubber, Plastic etc.

9. Combustibility- The property of materials by which they can catch fire is called combustibility and such substances are called as combustible substance. e. g.- LPG, Petrol, diesel, Kerosene, Wood etc.