Sorting Materials Into Groups

Sorting Materials Into Groups

Placing or sorting similar things together is called grouping. Grouping makes it easier for us to find things when we need them.

GROUPING ON THE BASIS OF COMMON PROPERTIES

Objects are made of different materials. One material can be used to make different objects. This is possible because different types of materials have different properties. We have to choose materials with the right properties based on what we want to use it for. For example, a chalk made of wood or plastic would be of no use because it cannot be used to write on the blackboard.
Materials have different properties like roughness, lustre, transparency, solubility, flotation, attraction towards a magnet, conduction of heat, and conduction of electricity. Let us study these properties one by one.

Roughness

Materials can be rough or smooth. Rough materials have bumps or ridges on their surface, which can be felt by touching them. Smooth materials lack these bumps. Examples of rough materials are rocks, sandpaper, and bark of a tree. A glass sheet, flower petals, and surface of an apple are some examples of smooth surfaces.
Sorting Materials Into Groups 1

Lustre

Lustre is the shine of a material. All metals in pure state are shiny and said to possess lustre. This property of metals is widely used for making jewellery and other decorative articles. Materials like gold, silver, and bronze have lustre.

Sorting Materials Into Groups 2
Fig. Metals have lustre

Transparency

Different materials allow different amounts of light to pass through them depending on a property called transparency. Based on transparency, materials can be of three types: transparent, translucent, and opaque.

Sorting Materials Into Groups 3
Transparent jar

Materials that allow all the light to pass through them are called transparent materials. Glass, water, acrylic sheet, and cellophane paper are transparent. Shopkeepers generally prefer to keep items like toffee, biscuit, sweet, etc. in transparent jars so that we can see them easily. Windows are also usually made of glass so that light can pass through and light our rooms.

Materials that allow some light to pass through them are called translucent materials. Oiled paper and coloured glass are translucent materials. Materials that do not allow light to pass through them are called opaque materials. Wood, metal, leaf, stone, and cardboard are opaque materials.

State

All substances are made up of matter. Matter exists in three states – solid, liquid, and gas.
Table shows Grouping based on the states of matter

SolidLiquid

Gas

Definite shape and volumeDefinite volume but no definite shape. They take the shape of the container they are poured into.No definite shape and volume
Cannot be compressedCan be compressed to a small extentHighly compressible
Particles are closely packedParticles are not as closely packed as inParticles are loosely packed

Sorting Materials Into Groups 4

Flotation

Certain materials float on water whereas others sink. This property of a material to float on water is called flotation. Generally, materials like wood, leaf, and feather float on water whereas rock and metal sink.
Sorting Materials Into Groups 5

Attraction towards a magnet

Materials that are attracted to a magnet are called magnetic materials. This property is called magnetism. Objects made of iron are attracted to a magnet. In addition to iron, nickel and cobalt are also attracted to a magnet.

Activity

Aim: To classify the given materials as magnetic or non-magnetic.
Materials needed: Pins (made of metal), clips (made of plastic), pencil, eraser, water, glass, cardboard, comb, nails, iron key, rock, sewing needle, paper and a magnet.
Method:

Sorting Materials Into Groups 61. Bring the magnet near the objects one by one.
2. Observe which objects are attracted towards the magnet and which are not.
Observation: Pins, nails, key, and sewing needle are attracted to the magnet. Eraser, clips, pencil, water, comb, rock, glass, cardboard, and paper are not attracted to the magnet.
Conclusion: Some materials are magnetic and some are non-magnetic.