Matter is anything that takes up space. Matter comes in three ordinary states; solid, liquid and gas. Matter is made up of particles.
The smallest unit of a particle is called the atom. Atoms combine is different ways to create molecules. The structure of molecules determines the characteristics of matter.
Solids are matter that you can handle with your hand. Solids have a defined shape and will often create friction when you rub against it. The molecular structure of solids is compact, giving it stability and shape.
Liquids are a form of matter that is able to flow. Liquids have no defined or stable shape. They take on the shape and volume of the container it is poured into. The molecules of liquids are packed loosely enough to make it flow but tight enough to give it volume.
Gases have molecules that are energized and move around constantly. Gases expand outward until they come into contact with a solid surface.
STATES OF MATTER
Matter can change from one state to another. For example, water can be found in three states, solid, liquid or gas. The state it is in depends on the amount of energy acting upon it.
Water becomes a solid when heat energy is removed from it so it freezes and becomes ice. Ice can be changed into liquid by heating it to room temperature. If it is heated further to boiling point water changes into steam (its gas form).