Ch – 4 Sorting Materials Into Groups

  • All objects around us are made of one or more materials.
  • Grouping is done on the basis of similarities or dissimilarities of materials.
  • The properties of materials are Appearance, Hardness, Solubility, Transparency, etc.
  • Some materials can be lustrous or non-lustrous in appearance.
  • Lustrous materials are diamond, freshly cut metals, gold foil, etc.
  • Some metals often lose their shine and appear dull, because of the action of air and moisture on them. We therefore, notice the lustre, only on their freshly cut surface.
  • Non-lustrous materials are wood, rusted iron, blackboard, etc.
  • Materials which can be compressed or scratched easily are called soft. For eg: cotton, sponge.
  • Materials which are difficult to compress are called hard. For eg: Wood, Stone.
  • In appearance, materials can have different properties, like lustre, hardness, be rough or smooth.
  • Some substances completely disappear or dissolve in water. They are known as soluble substances. Eg: Sugar, Salt.
  • Some substances do not mix with water and do not disappear even after we stir for a long time are known as insoluble substances. Eg: Chalk powder, Sand.
  • Some liquids mix with each other completely, are known as miscible liquids. Eg: Chocolate syrup with milk.
  • Some liquids do not mix with each other and form a separate layer, are known as immiscible liquids. Eg: Oil and water.
  • Water plays an important role in the functioning of our body because it can dissolve a large number of substances.
  • Those substances or materials, through which things can be seen clearly, are called transparent. Eg: Clean water, Plain glass.
  • Some materials through which you are not able to see. These materials are called opaque. Eg: Book, Wooden door.
  • The materials through which objects can be seen, but not clearly, are known as translucent. Eg: Coloured glass, Butter paper.
  • We often group materials for our convenience.
  • Dividing materials in groups makes it convenient to study their properties and also observe any patterns in these properties

Published by Priya Prakash

In the midst of winter, i found there was within me an invincible summer ~ Albert Camus

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