We know that matter can change its shapes as matter consists of tiny particles. But what are the characteristics of these particles of matter? What is the science behind it? Let’s us find out more them below.
Characteristics of Particles of Matter
These are the four main characteristics of particles of matter :
- Particles of matter are very tiny in size.
- They have spaces between them.
- Particles of matter move constantly.
- They are attracted towards each other.
I. Particles of matter are very tiny
- Take a beaker and fill it with 10 mL of water and add two to three crystals of potassium permanganate.
- Now take few measuring cylinders and label them as 1,2,3, 4 … and so on.
- Next, fill these cylinders with 50 mL of water. Transfer 5 mL of the solution to the measuring cylinder 1 which has 50 mL of water from the beaker. Mix the water and the solution.
- Now, take out 5 mL of the solution from cylinder 1 using a pipette and transfer it into measuring cylinder 2. Shake this mixture.
- Take out 5 mL of the solution from cylinder 2 using a pipette and transfer it into measuring cylinder 3. Shake this mixture.
- Carry on this process of dilution of the solution in a similar manner.
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The solution held in the various measuring cylinders are all colored, even though the color gets fainter and fainter with successive dilution.
It can be concluded that a small crystal of potassium permanganate contains a very large number of tiny particulate matter showing the properties of the parent substance.
Note: The size of particulate matter in any form is of the order 10-9 m.
II. Particulate matter has interparticle spaces between them
Take a beaker and fill it with 100 mL of water. Now mix 20 gram of sodium chloride – NaCl (Table salt) with it. Stir it with a glass rod until the salt has been dissolved in water. When the salt is dissolved we get a solution.
It is observed that even if you dissolve 20 gram of salt in 100 mL water, the volume of the water doesn’t increase. This shows that the particles of water are loose and have interparticle space. This space is the inter-molecular space or interparticle space. This interparticle space has accommodated the dissolved salt particles.
III. Particles of matter are at constant random motion
Diffusion and Brownian motion give the evidence that particles are in motion.
The mixing and spreading out of a substance with another substance due to the motion of its particles is diffusion. This process goes on until a uniform mixture is formed. For example a gas jar full of bromine vapors and invert another gas jar that consists of air over it. It is noticed after some time, the red-brown bromine vapors spread out into the upper gas jar that has air. This mixing occurs due to diffusion. Diffusion occurs in liquids, solids, and gases but is the fastest in gases and slowest in solids. The rate of diffusion increases with an increase in the temperature of the diffusing substance.
Robert Brown gave the best evidence for existence and movement of particles in the year 1827. He suspended some pollen grains in water and then looked through a microscope. He observed that the pollen grains were moving in a zigzag manner. The movement further increases when the water is warmed.
Water is made up of atoms that move randomly. Thus, the moving atoms constantly hit the pollen grains making them move on the surface. This motion of the pollen grains is an example of the Brownian Motion. This was first noticed by Robert Brown and is called Brownian Motion.
IV. Particles of matter attract each other
There’s a force that acts on the particulate matter that keeps it together. Some substances change into powder, some others change into small crystals and others don’t break easily. The magnitude of the force of attraction varies from matter to matter, i.e. depends on the nature of the matter.
For example, breaking a chalk is easier than breaking a nail. This proves that attraction varies from particles of one substance to another. Cohesion means the force of attraction between the particulate matter of the same substance.
Question For You
Q. Which of the following statements is true?
- Particles of matter are big.
- They have spaces between them.
- They do not move.
- Particles of matter do not attract each other.
Sol: Statement b is the only true statement. Particles of matter do have spaces between them. The rest of the statements are false.