Sorting Materials into Groups

Class 6 Science | CBSE NCERT Curriculum

This chapter explains how objects around us are made of different materials, their properties including appearance, hardness, solubility, float/sink, and transparency, along with grouping of materials based on these properties.

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Quick Revision: Sorting Materials into Groups

  • Objects and Materials: All objects around us are made of one or more materials like wood, metal, plastic, glass, cotton, paper, etc.
  • Properties of Materials: Different materials have different properties that determine their use.
  • Lustre: Shiny appearance of materials. Metals like iron, copper, aluminium, gold have lustre. Non-metals like wood, paper do not.
  • Hardness: Hard materials are difficult to compress or scratch (e.g., iron). Soft materials can be easily compressed or scratched (e.g., cotton, sponge).
  • Soluble/Insoluble: Soluble substances dissolve in water (e.g., salt, sugar). Insoluble substances do not dissolve (e.g., sand, chalk powder).
  • Float/Sink: Materials lighter than water float (e.g., wood, paper, oil). Materials denser than water sink (e.g., iron, stone).
  • Transparency: Transparent materials allow clear visibility (glass, water). Translucent allow partial visibility (oiled paper, frosted glass). Opaque allow no visibility (wood, metal).
  • Grouping Convenience: Grouping materials helps in study, storage, and easy location of objects.

Chapter Summary: Sorting Materials into Groups

This chapter introduces the concept that objects around us are made from different materials. Materials can be classified based on their properties such as appearance (lustre), hardness, solubility in water, whether they float or sink, and transparency. Metals typically have lustre, are hard, and sink in water. Non-metals like wood and paper are generally non-lustrous, may float, and are opaque.

Materials that dissolve in water are called soluble (salt, sugar), while those that do not are insoluble (sand, chalk). Transparent materials allow light to pass through clearly, translucent materials allow partial passage, and opaque materials block light completely. Grouping materials helps us study their properties systematically and makes everyday storage and identification convenient.