Consider the world around us. All things in it that are physically real—from the air we breathe to the ground we walk on to the sun’s rays that warm us—are forms of either matter or energy. Scientists define matter as everything in the universe that has mass and occupies space.

Chemistry is an experimental science that involves measuring and calculating. Measurement is the determination of the size or magnitude of something. These scientific measurements are mostly quantitative. A quantitative measurement provides numerical information whilst qualitative description, on the other hand, does not provide numerical values but rather certain observations made on a compound. For example, the colour of a compound can be used to tell the kind of elements in it.

A laboratory is a place where experiments are carried out. It is equipped with certain standard apparatus which the student ought to be familiar with and how to use them. Students should know how to handle equipment and clean them properly after use. Using clean apparatus is very essential. The accuracy of the experimental result can be affected if unclean apparatus are used.

When charcoal (carbon) is exposed to the atmosphere for several hours or even days, it does not burn. For it to burn it must be lighted first. The element phosphorus is kept under water because if it is exposed to the air it will immediately and automatically burst into flames and burn. Phosphorus is said to burn spontaneously in the air without an input of energy from the outside. The burning of carbon in the air is non-spontaneous because an initial input of energy from the outside is required to start the process.

In nature, all things are either living or non-living. Biology as a field of natural science deals with all life forms ranging from unicellular micro-organisms like bacteria to multicellular complex organisms like plants and humans. There are two main branches of biology namely; botany which is the study of plants and zoology which is the study of animals. There are other related fields of study that depend on biology like biochemistry, genetics, and evolution.

Biology is all about studying life and living organisms. We are living organisms and we eat living organisms, so you could probably guess that it has something to tell us about what is going on all around – and inside – us. But how important is biology to our everyday routines?

Every organism has a way in which its body parts are shaped and distributed in the body known as the body plan. Some organisms possess some repetitive parts in an orderly manner. Some organisms such as sponges and amoeboid protozoans are irregularly shaped and the shape also keeps changing and therefore, it becomes difficult to give a particular body plan to them

Have you ever fallen sick or seen somebody sick? What are the things that you saw or felt that informed you of sickness? I believe you wondered what caused the sickness.

If you build a model car, you usually begin with the body framework. Then you add coving or paint. Finally, you add the engine, wheels, and other parts. However, the strength of the entire structure depends on the basic framework. Like the model car, vertebrates have a strong supporting structure. This is their internal skeleton or endoskeleton. Today, we shall be looking at the skeletal system.

There are about 2 million organic compounds and about 100,000 inorganic compounds. Why are there so many organic compounds? How important are organic compounds? How different are they from inorganic compounds? The answers to all these questions will be obvious by the end of the lesson.

In our previous lesson, we classified substances into organic and inorganic compounds. We also classified inorganic compounds as acids, bases, salts, and oxides. In this lesson, we shall discover the various classes of organic compounds.