Matter Nature and Behaviour

Matter –

  • Anything that occupy space and have mass is known as matter.
  • Early Indian philosophers classified matter in the form of five basic elements-the 'PanchaTatva' - air, earth, fire, sky and water. According to them, everything, living or non-living was made up of these five basic elements.

 PHYSICAL NATURE OF MATTER:

Particle Nature of Matter – Matter is made up of particles

  • To show the particle nature of matter, we perform the following experiment:
  • Experiment: Take about 50ml water in a graduated cylinder and dissolve small amount of common salt (NaCl) or sugar in it with the help of a glass rod.
  • Observation and explanation: The salt or sugar dissolves in water and there is no noticeable change in the level of water. This is because, there are some spaces in between the particles of water, which are occupied by salt or sugar particles (when salt or sugar dissolves in water) and thus the level of water does not rise.

  • When salt dissolves in water, the particles of salt get into the spaces between the particles of water and the level of solution does not rise
  • Conclusion : From above experiment, we led to conclude that, there are some spaces between the particles of matter, or in other words matter is made up of particles.

 The particles of matter are very small – they are small beyond our imagination. 

Consider an activity:

  • Take 2-3 crystals of potassium permanganate and dissolve them in 100 ml of water in a beaker.
  • Take out approximately 10 ml of this solution and put it into 90 ml of clear water in second beaker. Due to this dilution, the color of potassium permanganate solution in the second beaker becomes a bit lighter.
  • Take out 10 ml of this solution and put it into another 90 ml of clear water in third beaker. The color of solution will become still lighter.
  • In this way, we get a very dilute solution of potassium permanganate in water but the water is still colored.

  • This experiment shows that just a few crystals of potassium permanganate can colour a large volume of water.
  • So we conclude that there must be millions of tiny particles in just one crystal of potassium permanganate, which keep on dividing themselves into smaller and smaller particles.

 Characteristics of matter

Particles of matter have space between them.

The spaces between the particles of matter can be shown by performing the following experiment by using water and sugar.

  • Take a 100 ml beaker.
  • Fill half the beaker with water and mark the level of water.
  • Dissolve some sugar (50gm) with the help of a glass rod.

 

  • When sugar is dissolved in water, its crystals separate into very fine particles. These particles of sugar go into the spaces between the various particles of water due to which there is no change in the volume of water on dissolving sugar in it.

 Particles of matter are continuously moving that is they possess kinetic energy.

It can be shown by performing the following experiment by using potassium permanganate and water.

  • Procedure :

1. Take a beaker filled with 100ml of water.

2. Slowly add 5gm of KMnO4 crystals to water.

3. Observe the changes

  • As in above.

If we carry out this experiment by using hot water in the beaker (or gas jar), we will find that the water turns purple at a faster rate. This is because, on heating, the particles of water and that off potassium permanganate gain kinetic energy and move faster. And they mix into each other more quickly.

 Particles of matter attract each other.

Consider an activity-

  • If we take a piece of chalk, a cube of ice and an iron nail, and beat them with a hammer, we will find that it is very easy to break the piece of chalk into smaller particles, it requires more force to break a cube of ice, whereas the iron nail does not break at all even with a large force.

  • This shows that the force of attraction between the particles of chalk is quite weak; the force of attraction between the particles of ice is a bit stronger whereas the force of attraction between the particles of iron nail is very, very strong.

Existence of particles-

  • The existence of particles in matter and their motion comes from the conclusion of diffusion and Brownian motion.

Diffusion-

  • The intermixing of particles of two different types of matter on their own is called diffusion.
  • Order of rate of diffusion – gases> liquids>solids

Applications of diffusion-

  • When perfume (scents, incense sticks, room sprays, fragrance sprays) are sprayed at one part of the room, it spreads throughout the whole room due to diffusion.
  • Helium balloons deflate slowly and lose their lift. This happens because helium diffuses from the helium-rich area (balloon) to low helium area (outside environment).
  • When we put tea bags into a cup of water, it automatically mixes in the whole cup of tea, and it happens due to diffusion.
  • After a few seconds of opening a soda bottle, soda goes flat. This is because the CO2 (Carbon dioxide) concentration is higher in the bottle than the outside environment and hence, CO2 diffuses from its higher concentration to its lower concentration.
  • When we breathe the air, the inhale of oxygen and exhale of carbon dioxide is possible only because of the process of diffusion. Therefore, diffusion is a vital process in breathing.
  • When harmful gases, fumes, and toxic particles are released from various human-made sources including factories (like cement factory, chemical factories, brick kilns, etc), vehicles, and waste burning then they pollute the normal air with the process of diffusion.

 Factors affecting the diffusion:

The concentration gradient

The greater the difference in concentration, the quicker the rate of diffusion.

The temperature

The higher the temperature, the more kinetic energy the particles will have, so they will move and mix more quickly.

The surface area 

The greater the surface area, the faster the rate of diffusion.

 Brownian movement

  • The zig zag movement of small particles suspended in a liquid or gas is called Brownian movement.
  • It increases on increasing the temperature.
  • This movement resembles the exact motion of pollen grains in water as explained by Robert Brown.
  • Albert Einstein's later explained the Brownian movement more clearly in his paper stating that the pollen was moved by water molecules.