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400
Leucippus
Leucippus is the Greek philosopher that founded the idea of atomism in the fifth century BCE*. Although Democritus is credited with the naming of the atom, it was his teacher Leucippus who came up with the idea of there being the smallest object, the building block that cannot be divided and is part of everything.
*Note: The timeline does not state that the date is before the Common Era -
400
Democritus
The student of Leucippus, Democritus, is the most famous of the philosophers who theorized about the atom and the philosopher accredited for naming the atom in the fifth century BCE. He theorized that the atom was the smallest substance that cannot be split and that the atom was the only thing that existed other that the void, which is nothing. -
Antoine Lavoisier
A French chemist, born in 1743, Antoine Lavoisier discovered that air is made up of two parts and named one Oxygen which is Greek for "Acid-former" and the other part Azote which is Greek for "no life". He also named Hydrogen, "water former". Apart from these main discoveries, Laoiviser discovered many other elements through his discoveries. -
John Dalton
John Dalton was born in England in 1766, he was most interested in meteorology but envisioned a view of atomism. Dalton decided on a way to measure compounds by finding a percentage of compounds they were in. He also expanded on many things in the atomic theory such as the forces of repulsion between two atoms and the bond that can occur between two elements. -
Dmitri Mendeleev
Dmitri Mendeleev may be named by some the father of the Periodic Table. He placed the 63 known elements that were known at that time into a table based on their atomic mass and grouped into similar characteristics. He also predicted that many more elements existed and understood that some of the known atomic masses may have been incorrect, hence he left room for improvement in his work. -
J. J. Thomson
J. J. Thomson was interested in the atom and reflected on it in many of his works before conducting closer experiments to learn more about it. His most famous experiment is that in which he separated different kinds of atoms and molecules by using positively charged rays and advanced the study of isotopes. -
Robert Milikan
Robert Milikan made many discoveries concerning the electric aspect of the atom. He proved that the charge of all Electrons were negative, demonstrating the atomic structure of an atom. -
Ernest Rutherford
Rutherford discovered that the atom consisted of the Nucleus and found that it was positively charged while the negetively charged Electrons floated around the Neutron in a cloud. -
Niels Bohr
Niels Bohr, born in Denmark in 1885, worked under JJ Thomson after he gained his doctorate in 1911. He began to work on finding out what the atoms sturcture looked like. Since Rutherford had said that the atom consisted of a positively charged nucleus and a negative cloud of electrons, Bohr found it to make no sense that the nucleus did not attract the electrons. He proposed that the atom has electron rings and that the elecrtons would move on to a higher ring once one was fulfilled. -
Otto Hahn
Otto Hanh, a German chemist, discovered Uranium Z the first step to the discovery of the atomic nuclear process. Hahn also discovered the reaction of certain elements would result in atomic explosions. -
James Chadwick
James Chadwick, born in 1981, made an important discovery to the science of atoms. He discovered that the Nucleus consists of two different things, Protons and Neutrons not just Protons. For this discovery he was awarded the Nobel Prize for Physics. -
Erwin Schrodinger
Most famous for his theory that a cat is both dead and alive at the same time if it is put in a box, Schrodinger has also advanced the theory of the atom. As he was not convinced of Bohr's model of the atom, he advanced the theory of how the electrons are not attracted to the Nucleus. -
Albert Einstein
Albert Einstein study on atoms led him to create a new tool to study the movement of atoms. He also reasoned that heat is an effect of an atoms contant motion, he conducted tests to prove and explain his theories in detail. Einstein also had a role in the creation of the atomic bomb, to his dismay, because of his research on how atoms move.
