Matter

In previous section 'Introduction', we have defined chemistry as a branch of science which deals with the matter, its properties, reactions etc. Today, we are talking about matter. What is this matter which makes up the chemistry? Well, this matter is everything around you, the chair, the computer, the keyboard, the books, the trees, and all such objects are called matter in science. After looking at such objects, what do you observe? You can find two characteristics same about these objects which are; (i) they have mass and (ii) they occupy space. Mass means the stuff stored in matter. Mass and weight are two different topics which will not be discussed in this tutorial. Therefore everything which have mass and occupy space (have volume) is called matter. Is water matter? Yes it is matter because it has both characteristics i.e. it has mass as well as volume (occupies space). Gases are also matter because they have mass and volume. Thus, it can be concluded that everything around us is consist of matter.

Matter exists in three states; (i) solid (ii) liquid and (iii) gas.  These three states are also known as phases of matter. These states have both characteristics of matter but differ in physical form. From example solid is hard and rigid (e.g. book etc.), liquid is fluid i.e. they can flow (e.g. water and oil etc.) and gases are shape less (e.g. air.)

   
  The states of matter can be changed by various facts such as by heating or pressurizing. For example ice is a form of water in solid state. When its temperature rises above the freezing point then it changes its form to water in liquid state. When the temperature of water (liquid) is heated to melting point then it changes to steam which is also a form of water in gaseous state. In doing so the chemical properties are not changed. One molecule* of water is composed of two atoms** of hydrogen and one atom of oxygen. This chemical composition does not change whether the water is in solid or liquid or gaseous phase (state).

We will discuss in detail about these states in the sub-sequent tutorial in the section ‘Matter’.

Two other states have been discovered. They can exist in extreme condition. These two phases will not b discussed here.

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molecule* and atom** will be described in the sub-sequent tutorials.