Matter is all around you. It is every where you look. The TV on your desk, your favorite soda, the air you breathe, and your pet hamster are made up of matter. Scientists use the word matter to mean anything that takes up space.
One way to describe matter is by its state, or form. In this section we will learn more about different states of matter.
There are three main states of matter on earth. They are:
Solid StateBack to Top
Solid under ordinary conditions ordinary conditions have definite volume and shape and tend to maintain these even under deforming forces. One can see and feel the shape of the solid. One can also describe how solids looks and how it feels.
In a solid atoms, ions and molecules are most tightly packed and the inter molecular force of attraction between the constituent particle are strong. As a result the particles do not have any freedom of motion that is the particle are fixed in their position.
The characteristic properties of solid are:
- A definite shape and volume
- No fluidity
Liquid StateBack to Top
The arrangement of constituents of liquid have neither the orderly arrangement as the constituents of solid nor the complete disorder as in gases. It is observed that some of the properties of liquids approach those of solids while some of the properties closely resemble those of gases.
The position of the molecules in liquids are not rigidly fixed. But the molecules in a liquid state have much shorter mean free path as compared to gas molecules.
Gaseous StateBack to Top
The gases will not maintain the volume and shape, and gases will completely fill the container in which they are introduced.
The characteristic properties of gases are:
- Gases are highly compressible:
- All gases, except few are colourless.
- It expand considerably on heating.
Changes in States of MatterBack to Top
A substance can change from one state to another state by gaining or losing kinetic energy. The gaining of kinetic energy by atoms results in a change from a solid state to a liquid state, from a solid to a gas or from a liquid to a gas. When atoms lose kinetic energy they change from a gas into a liquid, a gas into a solid or a liquid into a solid.
A change of state is usually reversible so that no chemical alteration occurs with a substance when it changes from one state to another state, that is the amount of kinetic energy is the only variable.
Example: Heating ice causes water to be formed whereas cooling water results in the formation of ice.
Sometimes the change of state is irreversible since the chemical structure of a substance is altered. For example, heating wood can result in burning, with formation of ash ash and gas or smoke. Cooling smoke and ash will not reform wood.
As temperature and pressure change, a pure substance can undergo a transition from one state to another. A solid can melt to become a liquid in a process fusion, or a liquid can freeze into a solid. A liquid can evaporate into a gas, a process is referred to as vaporization. Or gas can get condensed into a liquid. A solid can sublime directly into the gaseous state (sublimation), and a gas can get condensed directly into a solid.