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States of matter





States of matter:

On the basis of physical state, all the matter can be classified into three groups: Solids, Liquids and Gases.

Properties of Solids, Liquids and Gases:

S.No. Solids Liquids Gases
1. Solids have a fixed shape and fixed volume Liquids have fixed volume but they have no fixed shape Gases have neither a fixed shape nor a fixed volume
2. Solids cannot be compressed much Liquids cannot be compressed much Gases can be compressed easily
3. Solids have high densities Liquids have moderate to high densities Gases have very low densities
4. Solids do not fill their container completely Liquids do not fill their container completely Gases fill their container completely
5. Solids do not flow Liquids generally flow easily Gases flow easily
6. For example: Ice, coal, wood, stone, iron, etc. Water, milk, fruit juice, ink, petrol, etc. Air, oxygen, hydrogen, nitrogen, steam, etc.


Why Solids, Liquids and Gases have different properties:

  • According to the kinetic theory of matter, the particles of matter are in continuous motion and possess kinetic energy.
  • Some forces of attraction also exist between the particles of matter. These are called inter particle forces. The forces of attraction tend to hold the particles together and control their movements.

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

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

Test Your Knowledge

Fill in the blanks 1) On the basis of physical properties, matter is classified as _____, _______ and _____
2) On the basis of chemical properties, matter is classified as _____, _______ and _____.
3) The particles which make up matter are ____ and ____.
4) The zigzag movement of the small particles suspended in a liquid (or gas) is called _______
5) The particles of matter have __________________ between them.
6) The particles of matter are constantly _____
7) The best demonstration that particles of matter are constantly moving comes from the experiments on __________________ and ______.
8) The __________________ of attraction between the particles of the same substance  is known as cohesion.
9) The force of __________________ between the particles of chalk is quite weak, the force of __________________ between the particles of ice is a bit stronger whereas the force of __________________ between the particles of iron nail is very, very strong.
10)The force of attraction is maximum in the particles of  __________________ and minimum in the particles of a _____
11) Solids have a fixed shape and fixed __________________  Liquids have fixed __________________ but they have no fixed shape .Gases have neither a fixed shape nor a fixed __________________
12) According to the kinetic theory of matter, the particles of matter are in continuous motion and possess _______.
13)The forces of __________________ tend to hold the particles together and control their movements.
14) The spaces between the particles are the __________________ in solids, a little more in liquids, and the maximum in gases.
15) The forces of __________________ between the particles are the strongest in solids, less strong in liquids and negligible in gases.







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