Class -06
subject - science
chapter - 4
sorting materials into groups
We see around us, a chair, bucket, bullock cart, cycle, cooking utensils, books, clothes, toys, water, stones and many other objects. All these objects have different shapes colours and uses.
There are so many ways to groups objects. we have grouped objects on the basis of their shape or the materials they are made from.
All objects around us are made of one or more materials. These materials may be glass, metal, plastics, wood, cotton, paper, mud or soil.
Objects and the materials they are made of
Different types of objects that are made from the same material.
** We found that objects around us are made of different materials.
**An object is made of a single material.
** An object could also be made of many materials.
** One material could be used for making many different objects.
Properties of materials :-
(1) Appearance:- Material usually look different from each other. Wood looks very different from iron. Iron appears different from copper or aluminium.
There are some similarities between iron, copper and Aluminium that are not there in wood.
** Materials that have such luster are usually metals. Ex- Iron, copper, aluminium and gold.
** Some metals are loose their shine and appear dull, because of the action of air and moisture of them.
(2) Hardness :- Materials which can be compressed or scratched easily are called soft. While some other materials which are difficult to compressed are called hard.
Ex. Cotton or sponge is soft, iron is hard
(3) Soluble or insoluble :- Some substances have completely disappeared or dissolved in water. These substances are soluble in water.
Ex. Salt, sugar etc.
** Some substances do not mix with water and do not disappear even after we still for a long time. These are insoluble in water.
Ex. Soil, kerosene, oil etc.
** Some gases are soluble in water where as others are not.
** Water has small quantity of some gases dissolved in it. Ex. Oxygen gas
Solubility of some common liquids in water
(4) Objects may float or sink in water :- Some of materials that not mix with water, floated to the surface of water.
Ex. Wood, leaves, plastic ball etc.
(5) Transparency
[A] Transparent :-Those substances or materials, through which things can be seen are called transparent.
Ex. Glass, water, air and some plastics.
[B] Translucent :- The materials through which object can be seen, but not clearly are known as translucent.
Ex. Oily paper.
[C] Opaque :- Some materials through which we are not able to see. These materials are called opaque.
Ex. Wood, cardboard, metal etc.
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