Page 2 - 3. LESSON NOTES-(CHARACTERISTIC PROPERTIES OF MATTER)

Particles Attract Each Other

Take an iron rod, a stick of chalk, and a pen. Try to break each one of these. Which
one of these is easy to break? The iron rod is stronger than the other two items. What
makes an item stronger? Yes, it’s the particles in them which are held by the inter-
particle force of attraction.

In every substance, there is an inter-particle force of attraction acting between its
particles. To break something, we need to overcome this force. The strength of the
force differs from one substance to another.

The inter-particle force of attraction and the kinetic energy of the particles primarily
determine the physical state of any matter.

Particles Have Space Between Them

There are small voids between every particle in a matter. This characteristic is the
concept behind the solubility of a substance in other substances. Let’s try to
understand this with an illustration.

Take a glass of water. Put a teaspoon of salt/sugar and mix them properly. You will
observe that the water is still clear. This is because the particles of salt/sugar get into
the interparticle spaces between the water particles. This proves that there are voids
between particles of a substance. If you add more salt/sugar, it will dissolve until all
the space between water particles get filled.

Particles Are Constantly in Motion (or) Particles are Continuously Moving

Particles of the matter show continuous random movements. The kinetic energy they
possess helps them in this movement. The spreading of ink in a beaker of glass, the
smell that comes from agarbattis, etc. are few illustrations that show the movement of
particles of a substance. When the particles of two different types of matters intermix
on their own, the phenomenon is called diffusion.

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