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460
Democritus
In 460 B.C. First to propose an atomic universe -
Period: 460 to
atomic
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Antoine lavioser
Discovered the role oxygen plays in combustion, and made the law of conservation in 1785 -
John Dalton
Made the atomic theory in 1803 -
Dimitri Mendeleev
Arranged elements into 7 groups with similar properties, discovered that the properties of the elements were periodic functions of their atomic weights, also known as the periodic law. -
Eugen Goldstein
cathode-ray tubes with a perforated cathode emit a glow from the end of the tube near the cathode. used a CRT to study canal rays which had electrical and magnetic properties opposite of an electron -
JJ Thomson
Discovered electrons in 1897, also had the plum pudding atom model -
Max Planck
Used the idea of quanta to explain hot glowing matter -
Robert Millikan
He determined the size of the charge on an electron by doing an oil drop experiment. -
Ernest Rutherford
The atom consisted of subatomic particles called protons and electrons. thought the protons in the nucleus and the electrons orbited around the nucleus like planets around the sun. also with radiations emitted from uranium and thorium and named them alpha and beta -
Niels Bohr
Discoverd the nucleus and developement of an atomic model, won nobel prize in 1908 -
Henry Moseley
Used x-ray tubes, determined the charges on the nuclei of most atoms, and also wrote the atomic number of an elemtent is equal to the number of protons in the nucleus -
Werner heisenber
Described atoms in means of formula connected to the frequencies of spectral liners. The principle of indeterminancy, you can not know both the postition and velocity of a particle -
Erwin Schrodinger
Viewed electrons as continous clouds and introduced wave mechanics as a mathematical model of the atom -
James Chadwick
Discovered the Neutron in 1932
