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400
Democritus
Democritus found the atom. all atoms are invisible, atom derives from atomos. Atomos is greek for invisible. -
Anoine Lovoisier
Law of Conservation of Mass, discovered mass and that it is the same in different forms. He also helped develop the metric system. -
Law of Conservation of Mass
Established by french chemist Antoine Lavoisier, states that mass is neither created or destroyed in any ordianary chemical reaction. -
John Dalton
He proposed atomic theory, with spherical solid masses in motion. Atoms can't be made or destroyed. -
Dmitri Mendeleev
Created first periodic table. Later won a noble peace prize for it. -
J.J. Thomson
He descovered the electron, he described atoms as ball or positive charge containing a number of electrons. -
Robert Millikan
Credited with measuring the charge of an electron and the oil drop experiment. -
Cathode Raytube
Karl Ferdinand Brain invents Cathode Raytube, forerner for radar and ratio tubes. -
Plum Pudding Model
Electrons surround positive charge. -
Ernest Rutherford
Conducted gold foil experiment; atoms are mainly open space with small hard nucleas in center. -
Electon Cloud Model
Modern day model of an electron cloud. -
Neils Bohr
Credited with "Bohr Planetary Model" and theory that electrons travel in specific planes. -
Henry Moseley
Sorted elements based off of their atomic number instead of atomic mass. -
Quantum Mechanical Model
Modern day model of an atom. -
Erwin Schroclinger
credited with mathmatically showing where electrons are in an atom. -
James Chadwick
Is credited with the discovery of the neutron.