Properties of Materials
Objects are categorised on the basis of their shapes, the materials they are made up of, and the properties of these materials.
- All objects around you have definite shapes. For example, eggs are oval and ice-cream cones are conical in shape. Objects can be classified on the basis of their shapes.
- Objects can be made from many different kinds of material, such as plastic, wood, glass, metal, cotton, paper, leather, wool, rubber, and even soil. Therefore, all objects can be grouped on the basis of the material that they are made from.
- Sometimes, the same object can be made from different materials.
For instance, a pen could be made from metal or plastic, your shoes could be made from leather or cloth, and even the tumbler that we drink from could be made from plastic, glass or metal. Bottles could be made from plastic or glass, and chairs could either be wooden, metallic or plastic.
Property - Lustre:
Materials can be grouped as lustrous and non-lustrous on the basis of lustre/shine possessed by them.
Lustrous materials are those that have a shine on them. E.g. gold, silver and most metals are lustrous in nature.
Non-lustrous materials are dull in appearance. E.g. wood, plastics.
Property - Hard/Softness:
Materials that can be compressed or scratched easily are called soft materials. E.g. Cotton, Sponge.
Some materials that are difficult to compress are called hard. E.g. iron and most of the other metals.
Property - Soluble or Insoluble:
A substance (solid or a liquid) is said to be soluble in water if a single layer is observed. E.g. Lemon juice, vinegar, sugar, salt are completely soluble in water and form a single layer with water. Materials (solids or liquids) that form distinct layers with water are said to be insoluble in water.
Property - Float or Sink:
Materials that are insoluble in water either float on the surface or sink in water. Light materials float in water. E.g. paper, Plastic boll etc.
Heavy materials sink in water. E.g. metals, stones etc.
Property - Transparency:
Materials can be classified as transparent, opaque and translucent on the basis of transmittance of light by them.
Transparent materials allow light to pass through them completely. One can see through such materials
E.g. Glass,Wwater, Air and Some plastics
Opaque materials do not allow light to pass through them. You cannot see through them. E.g. Wood, Cardboard and Metals.
Translucent materials allow light to pass through them only partially. They are partially transparent and partially opaque. E.g. Butter paper, Frosted glass.