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400 BCE
Democritus
believed in the idea that matter is composed of tiny particles.
thought that both stones would have the same properties as the whole, even when cutting a stone into two pieces. Therefore if the stone were continually cut into smaller pieces, eventually, at some point, the stone would be physically impossible to see. -
400 BCE
Democritus
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John Dalton
developed a method to calculate atomic weights, structures, and formulated the law of partial pressures
calculates the atomic weights from the percentage compositions of compounds, using an arbitrary system to determine the likelihood of the atomic structure of each compound -
John Dalton
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John Dalton
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JJ Thomson
performed a series of experiments in 1897 designed to study the nature of electric discharge in a high-vacuum cathode-ray tube
Discovered the electron in 1897 which led to others studying it further. -
JJ Thomson
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JJ Thomson
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Robert Millikan
Proved that radiation in the form of electrons from the sun came from “extraterrestrial origins”. He also gave them the name “Cosmic Rays”
Got a Nobel prize in 1923 for his work on the study of elementary electronic charge and the photoelectric effect. -
Robert Millikan
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Robert Millikan
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Ernest Rutherford
Ernest Rutherford postulated the nuclear structure of the atom, discovered alpha and beta rays, and proposed the laws of radioactive decay. The gold-foil experiment was his experiment he conducted
Concluded that an atom was composed of mainly empty space and a nucleus -
Ernest Rutherford
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Arnold Sommerfeld
Developed the most accurate description of the atom at the time.
Furthered the research conducted on the atom at the time -
Arnold Sommerfeld
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Ernest Rutherford
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Niels Bohr
Claimed energy can only be transferred in well defined quantities
Claimed electrons only moved around the nucleus in a prescribed orbit -
Niels Bohr
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Henry Moseley
Did a self-built experiment to prove every element's identity is uniquely determined by the number of protons it has. His discovery lead to the reveal of the true basis of the periodic table
Demonstrated that the major properties of elements is determined by their atomic number -
Henry Moseley
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Henry Moseley
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Niels Bohr
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Erwin Schrodinger
Introduced Schrodinger's equation which proposed that atomic things happened in waves.
Most famous idea/experiment was Schrodinger's cat. Which was that there was an equal probability of an atom decaying or not decaying and the cat either being alive or dead. He also later said that he thought that his experiment/idea was not good. -
Erwin Schrodinger
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Erwin Schrodinger
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James Chadwick
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James Chadwick
Discovered the neutron which allowed others to study it further
Findings led to the invention of the nuclear bomb for better or for worse for mankind -
James Chadwick
