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500 BCE
Alchemists
The Alchemists believed that there were only four elements. Fire, water, earth and wind. -
460 BCE
Democritus
Democritus, a Greek philosopher, named the smallest piece of matter "atomos". -
Period: to
Charles de Coulomb
Coulomb is French physicist best known for his formulation of Coulomb's law, which states that the force between two electrical charges is proportional to the product of the charges and inversely proportional to the square of the distance between them. -
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Antoine Lavoisier
Lavoisier proposed the Combustion Theory which was based on sound mass measurements. -
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John Dalton
John Dalton proposed that all matter is composed of very small things which he called atoms. This was not a new concept as the ancient Greeks(Democritus) had already proposed that all matter is made up of small objects that cannot be divided. -
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William Crookes
William Crookes is responsible for reconstructing the Cathode Ray which discovered the element thallium and to show that there is a negative charge in atoms. -
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J.J Thomson
Thomson created the 'Plum Pudding' -
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Max Planck
Max Planck is best known for being the originator of the quantum theory of energy. His contribution contributed significantly to the understanding of atomic and subatomic processes. -
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Marie Curie & Pierre Curie (The Curies)
Pierre and Marie Curie are best known for their discovery in the study of radioactivity, which led to their finding in 1898 of the elements radium and polonium. -
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Robert Millikan
Robert Millikan's drop experiment determined the unit charge of the electron, which contributed to our current understanding of the structure of the atom and atomic theory. -
Period: to
Ernest Rutherford
Rutherford overturned Thomson's model in 1911 with his well-known gold foil experiment in which he demonstrated that the atom has a tiny and heavy nucleus. Rutherford designed an experiment to use the alpha particles emitted by a radioactive element as probes to the unseen world of atomic structure. -
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Albert Einstein
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Niels Bohr
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Erwin Schrodinger