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460 BCE
Democritus
He believed that all matter, time and space was made up of atoms -
Dalton
Agreed all matter was made up of atoms but believed that atoms were indestructible and that compound are the combination of two atoms. -
Mendeleev
Created the periodic table and justified that physical and chemical elements had to do with atomic number. -
Eugene Goldstein
He discovered that atoms had positive charges equal to electrons. -
Henri Bequerel
Discovered radioactivity -
Thompson
He discovered the electron and did experiments on it through a high vacuum cathode-ray tube. -
Max Planck
Used the idea of quanta to explain hot glowing matter. -
Rutherford
Used gold foil experiment to modern model of an atom. All positive charges were centralized and all electrons were orbiting. -
Millikan
Used the oil drop experiment to determine the charge of a single electron -
Neils Bohr
Discovered that the outer orbit can hold more electrons than the inner orbit. -
Fredrick Soddy
Came up with isotopes -
Heisenberg
The uncertainty principle means that you can't know the charge and the location of the electrons simultaneously. -
Chadwick
Discovered neutrons help balance out the protons.