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500 BCE
"Plum Pudding" Model
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500 BCE
Electron Cloud Model
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500 BCE
Solid Sphere Model
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500 BCE
Solar System Model
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460 BCE
Plato
Democritus was an influential Ancient-Greek philosopher primarily famous for the contribution to the history of the atom -
360 BCE
Democritus
The theory of Democritus held that everything is composed of atoms which are physically, but not geometrically, indivisible; that between atoms, there lies empty space that atoms are indestructible, and have always been and always will be in motion; that there is an infinite number of atoms and of kinds of atoms -
332 BCE
Aristotle
Aristotle’s idea, causing Democritus’ idea- which was that all substances on Earth where made of small particles called atoms -
Robert Boyle
It is Boyle's Law for which he remains most famous. This states that if the volume of a gas is decreased, the pressure increases proportionally. Understanding that his results could be explained if all gases were made of tiny particles, Boyle tried to construct a universal 'corpuscular theory' of chemistry -
Antoine Lavoisier
A later breakthrough in the discovery of the atomic model came through the work of French chemist Antoine Lavoisier who through a series of experiments found that the total mass of products and reactants in a chemical reactions is always the same. This led to the theory of the law of conservation of mass. -
John Dalton
Dalton’s atomic theory proposed that all matter was composed of atoms, indivisible and indestructible building blocks. While all atoms of an element were identical, different elements had atoms of differing size and mass -
The Alchemists
Dalton's most important contribution to science was his theory that matter is composed of atoms of differing weights and combine in simple ratios by weight -
Dmitri Mendeleev
Mendeleev found that, when all the known chemical elements were arranged in order of increasing atomic weight, the resulting table displayed a recurring pattern, or periodicity, of properties within groups of elements -
J.J Thomson
Thomson is credited with the discovery of the electron, the negatively charged particle in the atom. He is known for the Thomson atomic theory. -
The Curies
German physicist Wilhelm Conrad Rontgen had discovered X-rays in 1895, and Becquerel thought they might be related to fluorescence and phosphorescence, processes in which substances absorb and emit energy as light -
Albert Einstein
Albert proved the existence of the Atom in 1905. -
Ernest Rutherford
Ernest Rutherford postulated the nuclear structure of the atom, discovered alpha and beta rays, and proposed the laws of radioactive decay. He received the Nobel Prize in Chemistry -
Henry G J Mosley
Moseley never lost his enthusiasm for discovery and went on to study physics at Oxford University, earning his bachelor's degree in 1910 -
Robert Millikan
Learn about the life and achievements of American physicist Robert Millikan. His oil drop experiment helped to quantify the charge of an electron, which contributed greatly to our understanding of the structure of the atom and atomic theory -
Neils Bohr
In 1913, Niels Bohr proposed a theory for the hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities. Electrons should move around the nucleus but only in prescribed orbits. When jumping from one orbit to another with lower energy, a light quantum is emitted -
Werner Heisenberg
German physicist and philosopher who discovered a way to formulate quantum mechanics in terms of matrices
