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Democritus
In 400 B.C. Democritus was the first person to come up with the idea of an atom -
Period: to
Atomic Theory
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Antoine Laviosier
Laviosier created the Law of Conservation of Mass, which states that mass cannot be created or destroyed, by carefully measuring chemicals and their reactants before and after a chemical reaction. -
Joseph Proust
Proust studied copper carbonate and created gold from zinc, the two twin oxides, and the two iron sulfides to prove his law of definite porporations. This states that chemical compounds always have the same porportions by mass of their elements. -
John Dalton
John Dalton made the first model of the atom as well as creating the first official atomic thoeory. The atomic theory states that,all atoms are indestructible, all atoms of a given element have identicle mass properties, and that compounds are formed by a combination of two or more atoms. -
Dalton's Model
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Joseph Gay-Lussac
Measured gasses in a hot air ballon to find different temperatures/pressure/density. Then Gay-Lussac realeased his Law of Combining Volumes, gasses at stable temperature and pressure combine in whole number ratios. -
Amedo Avogadeo
Hypothesized that the relationship between gasses of the same volume corresponded to their molecular weights. Also came up with the mol, 6.02x20^23 -
Henri Becquearal
Discovered radiation by observing effects of X-rays on photographic film. -
J.J. Thomson
Used cathode rays to discover the electron and the proton. He used his findings to create a new atomic model. -
Marie and Pierre Curie
Compared radioactivity of pure uranium to uranium ore and found that the ore was much more radioactive, concluding that there must be additional radioactive elements in the ore (polonium and radium). -
Max Planck
Planck came up with quantum theory, which states the electrons are not emitted constantly but in small packets called quanta.He also came up with the constant h=6.26x10^34 -
Albert Einstein
Einstein suggested that light has a particle nature, proving the photoelectric effect. -
Ernest Rutherford
Used the gold foil experiment (bombarded gold foil with alpha particles and observed where they went) to determine that the atom is made of mostly empty space. -
Rutherford's Atomic Model
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Robert Millikan
Performed the oil drop experiment to determine the charge of an electron. -
Henry Moseley
He developed the application to use X-ray spectra to observe an atom's sructure. Also Moseley organized the periodic table by atomic number. -
Niels Bohr
Based his model off of Quantum theory form Planck, the plum pudding model from Thomson, and the Rutherford model from Ernest Rutherford. Improved upon them by explaining why the electons are not pulled into the nucleus. -
Bohr's atomic model
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Louis de Broglie
Postulated that waves could act like particles, as particles could act like waves. -
Erwin Schrodinger
Develped and equation to determine the probabilty of finding the electron in an atom. -
Schrodinger's Atomic Model
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Werner Heisenburg
Heisenburg's Principle say that it is impossible to know both the postion and the velocity of an electron at all times. -
James Chadwick
Discovered the neutron by calculating the mass of a neutral particle -
Linus Pauling
Published the close packed spheron model, which states that the nucleus can be viewed as a cluster of nucleons. -
Gunther Roland
Using an atom smasher in the Large Hadron Collider, Roland and his team found a link between the elusive ""God particle" and other elements.
