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Chapter 1 : Matter In Our Surroundings
As we look at our surroundings, we see a large variety of things with different shapes, sizes and textures. Everything in this universe is made up of material which scientists have named “matter”. The air we breathe, the food we eat, stones, clouds, stars, plants and animals, even a small drop of water or a particle of sand – every thing is matter. We can also see as we look around that all the things mentioned above occupy space and have mass. In other words, they have both mass* and volume**.
1.1 Physical Nature Of Matter
1.1.1 MATTER IS MADE UP OF PARTICLES
For a long time, two schools of thought prevailed
regarding the nature of matter. One school
believed matter to be continuous like a block
of wood, whereas, the other thought that matter
was made up of particles like sand. Let us
perform an activity to decide about the nature
of matter – is it continuous or particulate?
1.2 Characteristics Of Particles Of Matter
1.2.1 PARTICLES OF MATTER HAVE SPACE BETWEEN THEM
In activities 1.1 and 1.2 we saw that particles
of sugar, salt, Dettol, or potassium
permanganate got evenly distributed in water.
Similarly, when we make tea, coffee or
lemonade (nimbu paani ), particles of one type
of matter get into the spaces between particles
of the other. This shows that there is enough
space between particles of matter.
1.3 States Of Matter
Observe different types of matter around you. What are its different states? We can see that matter around us exists in three different states – solid, liquid and gas. These states of matter arise due to the variation in the characteristics of the particles of matter.
1.4 Can Matter Change Its State?
We all know from our observation that water
can exist in three states of matter–
• solid, as ice,
• liquid, as the familiar water, and
• gas, as water vapour.
1.5 Evaporation
Do we always need to heat or change pressure for changing the state of matter? Can you quote some examples from everyday life where change of state from liquid to vapour takes place without the liquid reaching the boiling point? Water, when left uncovered, slowly changes into vapour. Wet clothes dry up. What happens to water in the above two examples?
