Famous Dead Guy - Lee

Thales of Miletus- 620 BC

101

Thales of Miletus was the first person to investigate the basic principles publically.

Democritus- 440 BC

200

Used thought experiment to develope a basic idea of the first atom.

Aristotle- 340 BC

300

Did not believe in the atom theory. Aristotle thought of the Earth, wind, air, and fire theory.

Isaac Newton

Jan 1, 1704

Said that the atom was held together by a force.

Dalton

Jan 1, 1803

Came up with the first atomic theory and discovered that water is in the air.

Henri Becquerel

Oct 4, 1896

Discovered Radioactivity

J.J. Thompson

Jan 1, 1897

Was the first to discover atoms had a negative and positive charge

Millikan

Jan 1, 1908

Used the oil drop experiment and found the charge of an indiviual electron.

Gold Foil Experiment

Oct 4, 1910

Particles were fired through a thin gold sheet to see if they would pass straight through.

Rutherford

Jan 1, 1911

Used the gold foil experiment and discovered that all mass in found in the nucleus.

Bohr

Jan 1, 1913

Discovered that the electrons in an atom had certain orbits. This is what keeps electrons from spiralling inward and outward.

Francis Aston

Oct 4, 1919

Identified 212 natural isotopes

Schrodinger

Oct 4, 1926

Used mathematical equations to prove that electrons are in certain places.