Definition of Solids

Objects with definite size and shape are known as solids.

More About Solids:

  • The size and shape of the solid do not change by itself.
  • The molecules are held close together in a solid body.
  • The molecules inside the solid exert large attractive forces on each other.
  • The force of attraction is so great that each molecule is allotted a definite place, in the body.
  • The molecules inside the solids cannot move by themselves.
  • The molecules cannot leave the position allotted for them. They can only vibrate about their mean position.
  • The average distance between the molecules is very small (in the order of 10-10m).
  • The solids cannot be compressed because there is no space between the molecules to get compressed.

Example: Consider following piece of stone.

It cannot be compressed, because there is hardly any piece of space between molecules.
It has a definite shape and size because the force of attraction between the molecules is very high.

Worked Example:

State which of the following describes a solid.

    A. Particles move about freely at high speed.
    B. No Fixed shape and volume.
    C. Particles vibrate and cannot change positions.
    D. Fixed volume but no fixed shape.
    Correct answer is C


    Step 1:In gases particles move about freely at high speed, but the same is not possible in solids
    Step 2: Gases will not have any fixed shape or volume.
    Step 3: In solids the molecules can vibrate about their mean position but cannot change their respective position
    Step 4: Liquids have fixed volume but they will not have particular shape

    Related terms: Molecules | Liquids | Gases.
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