Introduction to Chemistry Classification of Matter Hot-air balloonists must understand the relationships between pressure, temperature, and volume of gases. Experimental studies to derive these relationships were the beginning of chemistry. Definitions and examples are given below. In fact, after we list the results, we will trace how some of the ideas developed - paying attention to the comments expressed above.
Classification is usually part of the early stages of understanding science.
First, we need to give a working definition of chemical change and of physical change. A change in the form of a substance, for instance, from solid to liquid or liquid to gas or solid to gas, without changing the chemical composition of the substance. As we will see later, chemical bonds are not broken in a physical change. Boiling of water and the melting of ice. The change of a substance into another substance, by reorganization of the atoms, i.e. by the making and breaking of chemical bonds.