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460 BCE
Democritus
He discovered that atoms were tiny and solid and that they were always moving around. He also discovered that atoms were indestructible and indivisible. -
Period: to
John Dalton
He discovered that all matter has atoms in it. He discovered the atomic theory - atoms are combined, separated, or rearranged but never changed. -
Period: to
Dmitri Mendeleev
He discovered that the atoms were related to the periodic table for what was in them. -
Period: to
Eugene Goldstein
He discovered that protons would reflect off electron atoms and attract positively charged atoms. -
Period: to
J.J. Thomson
He discovered the electron and that it had a negative charge. -
Period: to
Max Planck
He discovered that only certain amounts of energy could be given. He then was able to find the wavelengths of the atoms. -
Period: to
Robert Millikan
He discovered the oil drip experiment and could find the value of the electron charge. -
Period: to
Ernest Rutherford
He discovered that the atom had a nucleus inside. He realized this with the gold foil experiment. The nucleus is small, dense, and is positively charged. -
Period: to
Niels Bohr
He discovered that electrons move around the nucleus but can move to different energy levels. -
Period: to
Erwin Schrodinger
He discovered that you could use mathematical equations to find the electrons in the atom. -
Period: to
James Chadwick
He discovered the neutrons and protons give the atom some weight. The neutron is found in the nucleus and has the same mass as a proton. The neutron has no charge. -
Period: to
Werner Heisenburg
He discovered the theory of quantum mechanics.
