Sorting Materials Into Groups

 

We consider the following basic facts for understanding, to arrive at grouping materials:

  1. All things are made of one or more materials.
  2. Same things can be made from different types of materials.
  3. It may be man-made or naturally occurring.
  4. Materials occupy space.
  5. Materials have mass.
  6. Materials can be classified on the basis of physical state; as solid, liquid and gas.

Solid Liquid Gas

Solid:

Solid materials have definite shape and volume. Examples: metals, wood, stones, ice, plastics, glass, etc.

Liquid:

Liquid has indefinite shape but definite volume. Liquids take up the shape of the solid container they are placed in. Examples: water, oil, milk etc.

Gas:

Gas has indefinite shape and indefinite volume. Examples: Oxygen, nitrogen, carbon dioxide, etc.

Criteria for Sorting Materials:

  • Appearance: Different materials look different from each other. The appearance depends on colour, hardness, texture and lustre.
  • Hardness: Hardness is another property of materials. Some materials are very hard while some are very soft.
  • Hard: Materials which are difficult to compress are called hard, e.g. diamond, stone, wood, steel, etc. Diamond is the hardest natural substance.
  • Soft: Materials which can be compressed easily are called soft, e.g. chalk, cotton, rubber, etc.

Solubility or insolubility:

Soluble: Materials which easily dissolve in water are called soluble, e.g. salt, sugar, alum, etc.

Insoluble: Materials which do not dissolve in water are called insoluble, e.g. sand, chalk, iron, etc.

Water is considered as a universal solvent, so solubility in water is taken as the standard in most of the definitions; related to solubility.

Transparent:

The material which allows light to pass through it is called transparent material, e.g. acrylic sheet, glass, water, air, etc.

Opaque:

The material which does not allow light to pass through it is called opaque, e.g. wood, iron, asbestos, etc.

Translucent:

The material through which light can pass partially is called translucent, e.g. butter paper, thin curtain, etc.

Metals: Materials which are hard, have such luster and are good conductors of heat and electricity are called metals, e.g. iron, copper, gold, etc.

Non-metal: Materials which are brittle, which don’t have luster and are bad conductors of heat and electricity are called non-metals, e.g. coal, chalk, rubber, soil, etc.