What is chemistry?
• Chemistry is the science trying to understand how substances transform in other compounds with different properties.
The first researchers studying these transformations (I refer to scientists, not to the pre-scientific alchemists) did not know the real composition of substances. In fact, knowledge of matter composition comes in part from these initial studies of chemical transformations. However, it is much easier to understand chemistry having a basic knowledge of matter structure. That is, we recommend that first you visit pages related with the atomic structure of matter. Since substances consist of molecules and molecules are made of atoms, it is easy to infer that chemistry analyzes why atoms are able to reorganize to become another molecule or substance.
Some substances change (transformation in another compound) spontaneously (unstable molecules) or when you modify external conditions (temperature for example). However, most substances only change when they interact with another compound. That is, chemical transformations (chemical reactions) generally implies two o more different molecules. Chemistry tries to understand the laws controlling these interactions.
To sum up, chemists only analyze atom reorganization. Remember, because it is the base of all chemistry, that there is no change in the internal structure of atoms composing substances or molecules. If it takes place, then it is another story. We enter in atomic reactions and that is not chemistry. In fact, as you will see in next pages, atoms suffer some changes during chemical reactions, but these changes are limited to the more external cover of these atoms, then you can consider that there is no substantial alteration in the atomic structure. It is much simpler to make this assumption and it is not far away from reality.