Chemistry can be defined as the study of nature, properties, and composition of matter and its changes. It plays an important part in all the other natural sciences, basic and applied. Plant growth and metabolism, formation of rocks, the role played by ozone in the atmosphere, degradation of environmental pollutants, medical action of drugs, establishment of forensic evidence; none of these can be understood without the knowledge provided by chemistry. It is a field of interest for many people who study chemistry not to apply it to another field, but simply to learn more about the physical world and also the behavior of matter from a chemical point of view.

Chemistry is a way of studying matter which if we define in simple terms, could be anything that has mass and occupies space. Although we can very well define these two terms, but the process yields very little insight into what mater is we can simply say that matter is anything which has real physical existence, or in a word matter is just stuff. It can be either a pure substance or a mixture which has a fixed, characteristic composition and a fixed, definite set of properties. And so a collection of pure substances simply mixed together can be a mixture where its composition is variable, as are its properties.

One of the goals of chemistry is to be able to describe the properties of matter in terms of its internal structure and arrangement and interrelationship of its parts. Here the word structure refers to the physical arrangement of particles such as atoms and molecules. Such a structure of matter determines its properties. Properties can be classed as either physical or chemical. A physical property can be characterized without specific reference to any other substance usually describing the response of the substance to some external influences and chemical describes a chemical change: the interaction of one substance with other, or the change of one substance into another.

Properties may also be characterized as either macroscopic or microscopic. A macroscopic property describes the characteristics or behaviour of a sample which is large enough to see, handle and manipulate. A microscopic property describes the behaviour of a much smaller sample of matter. Chemistry also deals with composition, structure and properties of substances and the transformations that they undergo. In the study of matter, chemistry also investigates its interactions with energy and itself. Because of the diversity of matter, which is mostly in the form of compounds, chemists often study how atoms of different chemical elements interact to form molecules, and how molecules interact with each other. Thus it is clear that science has advanced in a series of fairly logical steps but the counterpart of these steps are difficult to identify in day-to-day professional activities.