States of matter

                 From previous tutorial we have learnt that matter is anything which occupies space and has mass. In this tutorial we are going to classify matter. Classification of matter is evolved on the basis of physical and chemical properties. In this tutorial we will learn about matter on the basis of its physical nature (physical property)

                 Look around. You can see things as books, trees, table water, ice and air ( cannot be seen but can be felt) etc. We know all these are matter because they occupy space and have mass but they have many different characteristics besides these two similar characteristics. Based on these different (physical) characteristics matter is classified in three groups. These groups are known as states of matter. Now scientists have discovered five states of matter but here we will discuss first three.

States of Matter.

                 To understand states of matter, first we have to get familiar with particles. Matter is composed of particles. What are these particles? Particles are too small that are beyond our imagination. They can be atoms or molecules. We will discuss more on them in subsequent tutorials. To understand their nature we assume them as small spherical balls. State of a matter depends upon the behaviour of these particles within the substances. Let's discuss the states of matter.

Solid states of matter

Matters is said to be solid when it has fixed shape and volume at a particulate temperature. Books, bricks, tables etc. are examples of solid. Do you observe some other characters of solid phase (state)? Probably you will have observed. Solids not only have fixed shape and volume but also they are rigid, incompressible, have higher densities compared to other states. What makes them to posses such characteristics? To understand, we will have to see the behaviour of particles in solids. You can see the particles in solids are tightly packed. The inter-particle force of attraction holds them in a fixed shape. As a result solids have tendency to maintain their shape i.e. they are rigid. The space between the particles is very less. Therefore they have the highest density if compared to liquid and solid. The kinetic energy of particles in solids is very less. Due to these characteristics of particles, solids have fixed shape and volume and highest density. They are rigid and incompressible.

Liquid state.

Liquid is a state of matter which has fixed volume but not fixed shape at a particular temperature. Water, oil, petrol and alcohol etc. are some examples of liquid. Liquids change their shape and take the shape of container in which they are kept. Therefore they are not rigid like solids. This property of liquid is known as fluidity. Particles in liquid are very apart from each other i.e. the distance between them is greater than in solids. This is the reason why they have lesser density than solids. It is also clear from this characteristic that why liquids do not have fixed shape. Therefore they assume the shape of the container in which they are kept. They are less tightly packed as compared to solids.

The Gaseous state

In gaseous state, matter has neither definite shape nor definite volume. Air, helium filled in balloon and steam etc. are examples of gaseous state. You can observe that gases are highly compressible. The gases are filled in cylinders under high pressure. Gases are also fluid. The space between their particles is the largest so particles moves freely. They have the highest kinetic energy as compared to liquids and solids. Gases have least density. Diffusion rate in them is the 
highest.