Science of substance is Chemistry
Chemistry is the science that studies substance. Structure, properties, composition and conversion of the substance. It deals with chemical elements and compounds. Elements and compounds are composed of atoms and molecules, as well as their relations. The basis is atomic theory. It says that all matter consists of very small particles (atoms).
The first law that led to the foundation was the law of conservation of mass. During the reaction there is no noticeable change in the volume of the substance. If at the beginning you have 100.000 atoms and make a lot of reaction, in the end you will have another 100.000 atoms. Weight remains the same if we count the energy that is gain or lost. Chemistry studies the relationships between the atoms. It used to be among the individual atoms. More frequently is when the atoms are linked to other atoms. Ions and molecules are then formed. It was found that the atoms almost always gained in certain proportions. There are exceptions called integrated circuits. Materials behave according to certain laws.
Second discovery is whenever is performed a certain reaction, the amount gained or lost energy is always the same. This is explained cases such as balance, thermodynamics and kinetics. Physical chemistry is based on modern physics, so it is possible to describe all chemical systems using the theory of quantum mechanics. The theory is mathematically complex and not used for normal work in chemistry. In practice, only the simplest chemical systems can investigate only through quantum mechanics and for practical purposes must work approximations. Therefore, in most of the chemistry does not require detailed knowledge of quantum mechanics. Although the quantum mechanics can often ignored, it's quantization of energy must be taken into account.