From the invisible to the visible world and back

Well.. the topic is very complicated to summarize but I'll tried.
"Demócrito" a greek philosopher,  expressed the idea that all matter was made up of many small, indivisible particles that he called atoms (which means indestructible and indivisible). Although the idea of ​​Democritus was not accepted by many of his contemporaries as "Aristóteles" and "Platón".. The experimental evidences of some scientific investigations supported the concept of "atomism".
In 1808, Jhon Dalton defined more precisely the invisible units that form matter, calling them atoms. His theory can be summarized as, The elements are made up of extremely small particles called atoms. All atoms of the same element are identical, have the same size, mass and chemical properties. The atoms of an element are different from the atoms of all the other elements; in general the compounds are formed by atoms of more than one element.
All modern chemistry is based on the fact that matter is composed of atoms, thanks to that we have been able understand the composition of our planet.
Each element has it's unique characteristics which are used to created materials with varied chemical and physical properties, which day by day helps us to facilitate our life, but like everything in life, it has to have it's bad side,which is that chemistry is used to create all kinds of weapons that end up destroying us.
This topic is very interesting and is the basis of my career.