CLASSIFICATION OF MATTER AS SOLIDS, LIQUIDS AND GASES

CLASSIFICATION OF MATTER AS SOLIDS, LIQUIDS AND GASES:Notes for SSC UPSC Exams

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

(i)                Sugar, sand, iron, wood, rocks, minerals and ice are solids,

(ii)               Water, milk, oil, kerosene, petrol and alcohol are liquids, and

(iii)             Air, oxygen, hydrogen, carbon dioxide and steam are gases.

Solids, liquids and gases are called the three states of matter. In other words, matter exists in three

Physical states : solid, liquid and gas. The solids, liquids and gaseous forms of matter have different Properties. The characteristic properties of solids, liquids and gases are given below. These properties can be used to distinguish between the three states of matter : solid, liquid and gas. Let us start with the Properties of solids.

Classification of Matter 
Notes for SSC UPSC Exams

Properties of Solids

Ice, wood, coal, stone, iron, brick, etc., are some of the common solids around us. The solids have the following characteristic properties :

1.      Solids have a fixed shape and a fixed volume.
2.      Solids cannot be compressed much.
3.      Solids have high densities. They are heavy.
4.      Solids do not fill their container completely.
5.      Solids do not flow.

Properties of Liquids

Water, milk, fruit juice, ink, groundnut oil, kerosene and petrol, etc., are some of the common liquids.

The liquids have the following characteristic properties :

• 1.      Liquids have a fixed volume but they have no fixed shape. Liquids take the shape of the vessel in Which they are placed.
• 2.      Like solids, liquids cannot be compressed much.
• 3.      Liquids have moderate to high densities. They are usually less dense than solids.
• 4.      Liquids do not fill their container completely.
• 5.      Liquids generally flow easily.

Properties of Gases

Air, oxygen, hydrogen, carbon dioxide, nitrogen and steam, etc., are some of the common gases. The Gases have the following characteristic properties :

• 1.     Gases have neither a fixed shape nor a fixed volume. Gases acquire the shape and volume of the Vessel in which they are kept.
• 2.      Gases can be compressed easily (into a small volume).
• 3.      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.
• 4.      Gases fill their container completely.
• 5.      Gases flow easily.

Why Solids, Liquids and Gases Have Different Properties?

We will now try to explain why solids, liquids and gases have different properties by using the kinetic Theory of matter. This is discussed below.Matter in all the three states, solid, liquid and gas, is made up of very small particles (atoms and Molecules). 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 interparticle forces. The forces of attraction tend to hold the particles together and control their Movements. The interparticle forces of attraction are the maximum when the particles are close together.As the distances (or spaces) between the particles of matter increase, the forces of attraction between them decrease. The movement of particles (or kinetic energy of particles) can be changed by heating the matter (or cooling it). Higher the temperature, greater is the movement of particles. We can now say that the Following properties of particles determine the physical state of matter. That is, the following properties Of particles decide whether a given substance will exist as a solid, a liquid or a gas :

1.      The spaces (or distances) between the particles. The spaces (or distances) 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 (or interparticle Forces) 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(or kinetic energy of particles) is the minimum in solids, more in liquids and the maximum in gases.

Keeping these points in mind, we will now describe the structure of solids, liquids and gases, and explain the difference in their properties on the basis of these structures.

Notes for SSC UPSC Exams/Chemistry Notes for SSC UPSC Exams

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