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The first breakthrough in the atmoic theory
The Greek philosopher Democritus hypothesized that all matter is composed of tiny indestructible units, called atoms. The atoms themselves remain unchanged, but move about in space to combine in various ways to form all microscopic objects. -
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Atistotle's theory
The Greek philisopher beleived Aristotle believed in the four elements of air, earth, water and fire. Aristotle felt that regardless of the number of times you cut a form of matter in half, you would always have a smaller piece of that matter. -
Isssac Newton on the atomic theory
Sir Issac Newton theorized a mechanical universe with small, solid masses in motion.. He was one of the earliest thinkers in modern science to suggest an "atomic" nature of matter, even though early Greeks did also suggest that. -
Robert Boyles Breakthrough about the elements
In 1661, at the age of 34, Boyle published The Skeptical Chymist. In this book he overturned Aristotle’s conception of the four elements (the belief that everything was composed of earth, air, fire and water) and replaced it with the modern idea of an element—namely that an element is a substance that cannot be separated into simpler components by chemical methods. -
Josheph Preistley's breakthrough on oxygen
Joseph Preiestley discovered oxygen (which he called "dephlogisticated air") in 1774. -
Antoine Lavoisier on the atomic theory
Antoine Lavoisier was the first person to make good use of the balance. He was an excellent experimenter. After a visit with Priestly in 1774, he began careful study of the burning process. He proposed the Combustion Theory which was based on sound mass measurements. He named oxygen. He also proposed the Law of Conversation of Mass which represents the beginning of modern chemistry. -
John Daltons major breakthrough on the atomic theory
John Dalton proposed the Law of Multiple Proportions. This law led directly to the proposal of the Atomic Theory in 1803. He proposed a system of symbols to represent atoms of different elements. -
Dimitri Mendeleev breakthrough on the preiodic table
Dimitri Mendeleev proposed the periodic law and developed the first periodic table in 1869. Medeleev's table was arranged according to increasing atomic weight and left holes for elements that were yet to be discovered. -
Ernst Rutherford
Ernst Rutherford proposed the nuclear atom as the result of the gold-foil experiment in 1911. Rutherford proposed that all of the positive charge and all of the mass of the atom occupied a small volume at the center of the atom and that most of the volume of the atom was empty space occupied by the electrons. -
James Chadwick
Chadwick discovered the neutron in 1932. Chadwick was a collaborator of Rutherford's. Interestingly, the discovery of the neutron led directly to the discovery of fission and ultimately to the atomic bomb.
