Matter concept for class 9 What is Matter for class 9?

Matter is any thing which has mass and occupies space. All solids, liquids and gases around us are made of matter. Scientist believe that matter is made of tiny particles that clump together. You cannot see these particles but you can see the matter, for example, a book, a car, a letter, a hand set, a piece of wood, tree, a bag etc. Think and add a few more exmaples from your day to day life.

CHARACTERISTICS OF MATTER

There are various forms of matter in the nature. The various forms of matter have some common characteristics. The generalcharacteristics have been discussed below:

(1) The Matter has Mass:

If we take two pieces of bricks of different size, we will find that one is lighter while the other is heavy. The small sized brick is lighter because it contains less matter, while big sized brick is heavier because it contains more matter. Hence, the amount of matter present in anything is called its mass The things may be invisible even then they will have some mass eg, the air. Although air is invisible even then it has someāœ”CHECK POINT Take one football bladder filled with air and hang it on one side of the beam of a physical balance and put weight on the pan hanging on other side untill balance becomes horizontal. Now remove the air from the bladder.What will you find and what does it indicates?

You will find that the end of beam (on which the bladder has been hanged) moves upward. This indicates that air has a mass. Therefore, all the matter forms of m er have mass Check Your Answer

ii) The Matter Occupies Space:You must have experienced this phenomenon during your everyday life. If one stool is placed in the comer of your drawing room, you know another stool cannot be placed in the same corner. If the space on your bookshelf is completely filled with the books, you cannot keep more books on it. The two trucks coming from the opposite directions in a narrow lane cannot cross each other as there is space only for one, If they will try to cross each other they will collide. Therefore, it is clear thatmatter occupies space.

(iii) The Matter has Inertia :If any thing is lying on any place, it will remain there until and unless some external force disturbs its position. Similarly if anything is in motion, it will remain in motion till some external force stops it. This is known as property of inertia. The matter itself cannot change its position. Suppose if a foot ball is placed in the centre of a playground, it will remain there till it is pushed by anybody. Similarly if the football is pushed by a player it will move on till it is stopped by other players or bythe friction of the play-ground.

(iv) The Matter is Effected by the Gravity:If anything is thrown upward with a certain force it will automatically come to the ground because of force of attraction exerted by the earth. This attraction is called gravity.When you throw a ball upward with a certain force, it will automatically come down on the earth because of earth’s gravity. The fruits always fall downwards from the trees because of this gravity. Similarly water always flows from higher level to lower level.

(v) The Matter cannot be Destroyed:In all physical and chemical changes, total mass of the matter before and after the change remains the same. This can beproved by a simple experiment performed by Lavoisier Lavoisier’s experiment – Lavoisier took tin metal in an airtight flask. The flask (with tin) was weighed. It was then heated Tis metal reacted with the oxygen present in the air of the flask and was converted into tin oxide. The flask was cooled and again weighted. It was found that the weight practically remains unchanged.

Characteristics of Particles of Matter:

(i) The particles of matter are very, very small: The matter is composed of small particles: To understand particle nature of the matter, let us perform one experiment. Take a beaker full of water. Now place a small crystal of blue vitriol (copper sulphate) in the water. You will observe that the water begins to become blue coloured and slowly the size of the crystal becomes smaller and smaller. The crystal has divided itself into number of smaller particles and ultimately it dissolves in water. This experiment suggests that matter is composed of small particlesii) The particles of matter have spaces between them:Is there vacant space between the particles of matter?

Let us perform the following experiments Experiment (1) Take a piece of chalk (used for writing on black board) and dip it into water. Some water is absorbed by thechalk. There are vacant spaces or pores in the chalk which are occupied by the water. Experiment (2)-Take a wide mouthed test tube, almost half filled with water.

Now put a sugar cube in the test tube and mark the water level with a glass marking pencil. The sugar cube will dissolve in water and the level of water will go down to a small extent. Why it so happened?

There are vacant spaces between the particles of water. This vacant space is occupied by the particles of the sugar and water level goes down up

ii) The particles of matter are constantly moving:This property can be explained by Brownian motion and diffusion Diffusion: It is the phenomenon in which the movement of molecules or particles occur from their higher concentrationtowards the lower concentration. “Intermixing of particles of two different types of matter on their own is called diffusion For eg: When a perfume bottle is open in one corner of a room, its fragrance spreads in the whole room quickly. The particles of perfume move rapidly in all directions and mix with the moving particles of air in the room

iv) Particles of matter attract each other: There are some forces of attraction between the particles of matter which bind them together.Cohesive force: The force of attraction between the particles of same substances is called Cohesive Force Adhesive force: The force of attraction between the particles of different substances is called Adhesive Force For eg: If we take a piece of chalk, a cube of ice and an iron nail and beat them with a hammer

Observation: Chalk will easily break into smaller pieces. More force is required to break a cube of ice. ‘Iron nail does not break

Conclusion: Force of attraction is quite weak in between the chalk particles. Force of attraction in between the particles of ice cube is a bit stronger.Force of attraction in between the particles of iron is very, very strong

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