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Class 6 Science - Lesson: Matter

All the materials on the Earth are known to be made of matter which exists in 3 different forms or states. In scientific terms, anything which occupies space (place) and has mass (weight) is termed as matter.

Matter is made up of small particles called molecules which can be further broken down into smaller particles called the atoms and each atom in turn consists of negatively charged particles called electrons, positively charged particles called protons and neutral particles called the neutrons. The atoms have the capability of either losing or gaining electrons.

The molecules, thus are bound together with the help of various bonds to form elements and compounds in the nature.

Characteristics of molecules

  • Molecules have space between them known as the inter-molecular space.
  • Molecules are in continuous motion and these always tend to move on gaining energy.
  • There exists an inter-molecular force of attraction between the molecules.

States of Matter

Based on the arrangement of molecules in matter, there are 3 different forms / states of matter. These are solids, liquids and gases.


The molecules are closely packed in solids thus giving them a definite shape with distinct boundaries and with a definite volume. There is no inter-molecular space (space between the molecules) and hence the force of attraction or the force of attraction between the molecules is too strong in solids. Hence, solids are not at all compressible and they tend to maintain their shape when subjected to external force. Solids are so rigid that it is difficult to change their shape though they are broken.


The molecules are loosely placed and there is gap between the molecules. Thus liquids have no definite shape but they take the shape of the container in which they are placed. Molecules move freely in liquids and thus the rate of diffusion in liquids is higher compared to solids. Hence solids, liquids and gases as well diffuse easily in liquids. The inter-molecular space is greater and the inter-molecular force of attraction is lesser but the force of attraction keep them binding and makes them to occupy definite volume.


The molecules are too far apart in gases which create a great distance between them. Thus the inter-molecular space is too large in gases because of which the gases do not have a definite shape. The molecules are in continuous motion in gases which makes them overcome the inter-molecular force of attraction and thus gases do not have a definite volume but they spread in the entire available space.