International Year of the Periodic Table (Bulgaria 2019)

Stamp International Year of the Periodic Table it reflects the thematic directions:

Chemistry is the scientific study of the properties and behavior of matter. It is a physical science within the natural sciences that studies the chemical elements that make up matter and compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during reactions with other substances. Chemistry also addresses the nature of chemical bonds in chemical compounds.

A chemist (from Greek chēm(ía) alchemy; replacing chymist from Medieval Latin alchemist)[1] is a graduated scientist trained in the study of chemistry, or an officially enrolled student in the relevant field. Chemists study the composition of matter and its properties. Chemists carefully describe the properties they study in terms of quantities, with detail on the level of molecules and their component atoms. Chemists carefully measure substance proportions, chemical reaction rates, and other chemical properties. In Commonwealth English, pharmacists are often called chemists.