Matter is defined as something that has weight, occupies some space, can be sensed and resists forces applied to it. Chairs, tables, beds, almirahs, blankets, soil, water, air, stone, milk, oil etc. are examples of matter. All matters are made of atoms and these atoms are indivisible. Different materials have different properties. The reason is different materials are made of different types of atoms.
All matter is made up of very tiny particles called atoms. A group of two or more atoms is called a molecule. A matter is composed of molecules. The states of matter depend upon the arrangement and bonding between the molecules. In solid state the molecules of a matter are bound to one another in place.The molecules are not free to move. So, solid state has a definite shape and volume.
In liquid state the molecules are bound to one another but the bond is weak and molecules have a bit space to more around. So, the liquid state has a definite volume but not shape. In gas the molecules are spread very far apart from one another. They are randomly arranged and are constantly moving at high speed. That’s why the gaseous state does not have any definite shape or volume.