Observe your home garden or school garden and any other calm environment during the day time. You will be able to see many things such as trees and animals etc. Also, you will hear many sounds. Not only that you will feel the heat of the sun and the soft breeze.

Copy the following table into your writing book. Fill in the table with your findings.

Having a mass - ✔️ Have not - ❌

Occupying space - ✔️ Doesn’t occupy - ❌

Does air has a mass? Does it occupy space? Let’s find it.

Let's do the following activity to find out whether air occupies space.

You will observe that the handkerchief is not wet. This is because there was air in the glass. So, water cannot enter the glass . The conclusion is that air occupies space.

Let’s do the following activity to find out whether air has a mass.

When the air in one balloon is out, you will observe that the meter ruler looses its balance. This happens because the air in the balloon goes out. Hence, you can come to the conclusion that air has a mass.

2.1 Matter and Energy

The things around us can be categorised as

• Things with a mass and occupy space

E.g : pen, water, air, table, milk

• Things without a mass and do not occupy space

E.g : light, heat, sound

Things with a mass and occupy space are known as matter.

We normally refer to things in daily life as matter.

Things without a mass and do not occupy space are known as energy.

The things around us can be dived into two main categories as matter and energy.

2.2 States of Matter

In our day to day life, we use matter such as firewood, kerosene, liquid petroleum gas (L.P. gas).

These matters can be categorised as follows.

Firewood is a matter in solid state.
Kerosene is a matter in liquid state.
L.P. gas is a matter in gaseous state.

Think about the things you use in your day to day activities and try to categorise them as solid, liquid and gas.

The states of matter are solid, liquid and gas.

Characteristics of Solids

Observe some solids. What can you say about their shapes and volumes?

The shape of solids does not change easily. They have a definite shape. Also, there is a definite volume for solids.

A solid has,

a definite shape
a definite volume

Characteristics of Liquids

Let's do the following activity to find out the characteristics of liquids.

In this activity, though you put the same volume of water into the containers, water takes the shape of the container. Hence, a liquid has:

a definite volume
no definite shape

Water, petrol, liquid milk, coconut oil are some examples for liquids.

Fig. 2.7 Some examples of liquids

Characteristics of Gases

Do you think that the empty bottle in figure

2.8 contains any matter? Let’s do the following

activity to find the answer.

When the bottle is in the position as in figure 2.9

(a), water doesn’t enter the bottle. But when the bottle is in the position as shown in figure 2.9

(b), bubbles come out and water enters the bottle. First, water didn’t go into the bottle because there was something in the bottle. At the next position, water entered the bottle because the air blocked in the bottle came out. So, it is clear that air occupies space.

You will see that the smoke in the first gas jar goes to the second gas jar as well. The conclusion is that gases do not have a definite volume and they spread throughout the container.

A gas has:-

no definite volume
no definite shape

Air around us, oxygen, carbon dioxide, water vapour are some exam- ples for gases.

The characteristics of solids, liquids and gases can be compared as follows.

2.3 Specific Properties of Solid Matter

There are different properties in different solid materials.

Therefore, the properties of solid matter should be considered when they are used.

Let’s do the following activity to find out the properties of solids.

You would have identified that solids have their own properties.The following table shows some physical properties of solids with examples.

Applications of Solids

Can you imagine the amount and types of solids used to build up the above house in fig 2.12 ?

The properties of materials used differ depending on the shape of each part, strength, and the area that should be covered. Also, building materials differ according to the area, location, climate, necessity of the person, space and income etc.

Think about the materials that are used to build doors, roofs, windows, floor, walls and grills of the above house. Think about their physical properties.

Gold, silver and copper are used to make jewellery because of their property of malleability and ductility. Due to these properties, these materials can be made into different shapes.

Teats and gloves are made of rubber because of their property of elastic nature.