Matter In Our Surrounding

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02 Physical Properties and States of Matter


  • Matter is made up of particles
  • Matter can be broken into millions of tiny pieces.
  • The particles of matter have spaces between them. Example: when a small amount of sugar is added to water, it mixes without increase in volume.
  • The particles of matter are constantly moving. Example: When a crystal of copper sulphate is added to water, blue colour of copper sulphate diffuses throughout the whole volume of water.
  • The particles of matter attract each other: Example: If you put your finger across running water from a tap, it breaks but when finger is removed, the stream of water regains.

States of Matter:

Variation in the characteristics of the particles of matter leads to various states of matter:


  • It is one of the fundamental states of matter.
  • Solids can be defined as the state of matter which has definite shape and volume and has a rigid structure.
  • Solids are most rigid, least compressible and show least thermal expansion among the three states.
  • Solids have high density.
  • The molecules of solids are tightly packed because of strong intermolecular forces.
  • So, they only oscillate about their mean positions.
  • On the other hand, liquids and gases possess the property of fluidity and can easily flow.
  • Examples: Sugar, sand, iron, wood, rocks, minerals and ice.


  • The liquid molecules are loosely packed due to weak intermolecular forces that are weaker than solids but stronger than that of gases.
  • The space in between the molecules of liquids makes their flowing ability easy.
  • Liquids can easily acquire the shape of a vessel and have a fixed volume.
  • Solids get converted into liquids when the temperature of solids is increased to a point where solids begin to melt.
  • Generally, the density of liquid lies between the density of solids and gases.
  • Liquids are slightly more compressible and thermally expandable than solids.
  • Examples: Water, milk, oil , petrol and alcohol.


  • Gases do not have any fixed shape or volume.
  • Gases acquire the shape and volume of the vessel in which they are kept.
  • The distances between the molecules are large.
  • Intermolecular distance is in the range ofin 10-7 – 10-5 the case of gases.
  • The intermolecular forces between them are negligible.
  • So gases undergo translatory, rotatory and vibratory motions.
  • They also possess high compressibility and thermal expansion.
  • Examples: Air, oxygen, hydrogen and steam.


  • Solids have a fixed shape, distinct boundaries and a fixed volume.
  • Solids cannot be compressed much.
  • Solids have high densities. They are heavy.
  • Solids do not fill their container completely.
  • Solids do not flow.
  • Solids have a tendency to maintain their shape when subjected to outside force.
  • Solids are rigid as they might break under force but it is difficult to change their shape.


  • Liquids have a fixed volume but they have no fixed shape.
  • Liquids take the shape of the container in which they are placed.
  • Like solids, liquids cannot be compressed much.
  • Liquids have moderate to high densities.
  • They are usually less dense than solids.
  • Liquids do not fill their container completely.
  • Liquids generally flow easily.
  • Solids, liquids and gases can diffuse into liquids


  • Gases have neither a fixed shape nor a fixed volume. Gases acquire the shape and volume of the vessel in which they are kept.
  • Gases can be compressed easily (into a small volume).
  • Gases have very low densities. They are very, very light. A gas is much lighter than the same volume of a solid or a liquid.
  • Gases fill their container completely.
  • Gases flow easily.

Why do Solids, Liquids and Gases have Different Properties?

The following properties of particles decide whether a given substance will exist as a solid, a liquid or a gas:

  • The spaces (or distances) between the particles. The spaces (or distance) between the particles are the minimum in solids, a little more in liquids, and the maximum in gases.
  • The force of attraction between particles. The forces of attraction between the particles (or interparticle forces) are the strongest in solids, less strong in liquids and negligible in gases.
  • The amount of movement of particles (or kinetic energy of particles). The movement of particles (or kinetic energy of particles) is the minimum in solids, more in liquids and the maximum in gases.

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