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400 BCE
Democritus
He is known for his atomic theory that states, that everything is composed of atoms and that atoms are indestructible units. -
384 BCE
Aristoteles
He was against Democritus' believe of the atom being indivisible. -
Antoine Lavoisier
Stated that matter conserves its mass even after chemical reactions. Creating the law of Conservation of Matter. -
John Dalton
Dalton produced the first useful atomic theory of matter. He expressed that atoms where the indivisible particles of matter. And he concluded that atoms of the same element are the same while atoms of different elements are different. -
Eugein Goldstein
Goldstein discovered that atoms had positive charges. -
J.J. Thomson
Thomson discovered the electrons. He declined Dalton's model of the atom being indivisible. And he stated that the electrons must be surrounded by a positive charge around the outside. His model was called the "Plum pudding model". -
Robert Millikan
He determined the mass of an electron and its electric charge. -
Ernest Rutherford
He suggested a new model, he said the positive charge should be focused in the center, or the nucleus. -
Henry Moseley
He discovered the atomic number. Discovered that the protons on the nucleus were different for each element, and that each element had a unique positive charge. -
Niels Bohr
Bohr suggested that electrons moved in orbits surrounding the nucleus. -
Erwin Schrodinger & Werner Heisenberg
Erwin and Werner developed a mathematical description for the way the electrons would orbit around the nucleus. They developed the Wave Mechanical formula which became the basic model for modern atomic theory. -
James Chadwick
Discovered that the nucleus contained a non charged particle, called the neutron.
