Atomic Structure Timeline

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Democritus

460 BC

Thought that the world was made up of smaller things. "by convention bitter, by convention sweet, but in reality atoms and void"

Aristotle

384 BC

Thought the World was made up of five Elements, These Include: Earth, Air, Fire, Water, Aether

John Dalton

1803

Proposed the Atomic Theory by combining both Democritus and Aristotle's Theories.

Joseph John Thomson

1897

Studied "canal rays" and found they were associated with the proton H +

Ernest Rutherford

1898

Studied radiations emitted from uranium and thorium and named them alpha and beta.

Max Planck

1900

used the idea of quanta (discrete units of energy) to explain hot glowing matter.

Robert Millikan

1908

Found out that the charge of the Electron is Neutral

Niels Bohr

1922

Developed an explanation of atomic structure that underlies regularities of the periodic table of elements. His atomic model had atoms built up of sucessive orbital shells of electrons.

Louis de Broglie

1924

He proposed that electrons could behave as waves under some conditions

Erwin Schrödinger

1927

dwin Schrodinger stated that rather than electrons being distributed within an electron configuration of shells and energy levels, they were arranged in orbitals which were systematically distributed within Electron Clouds.

Werner Heisenberg

1927

Described atoms by means of formula connected to the frequencies of spectral lines. Proposed Principle of Indeterminancy - you can not know both the position and velocity of a particle.

James Chadwick

1932

Discovered the Neutron