History of the Atom Timeline

Aristotle

350

• Born in 384 BC• Lived in Greece• Theorized that everthing was made out of four elements: fire, earth, air, water• Also believed that the four elements had certain qualities such as coldness, wetness, hotness and moistness• E.g. fire – hotness & dryness

History of the Atom

Period: 350 to Apr 21, 1932

Democritus

440

• Born in 460BC• Lived in Greece• Came up with the theory that everything can be broken down until you come up with single particles or atoms

Antione Lavoisier

Apr 21, 1777

• Born on the 26th of August, 1743• Lived in France• Discovered the difference between an element and a compound and defined the elements

John Dalton

Apr 21, 1803

• Born on September 6th, 1766• Lived in England• Created an early form of the atomic theory

JJ Thomson

Apr 21, 1897

• Born on 18th of December, 1856• Lived in England• Discovered the electron and that there were smaller particles inside the atom

Ernest Rutherford

Apr 21, 1909

• Born on 30th of August, 1871• Lived in England• Discovered the nucleus of the atom through his gold foil experiment.

Niels Bohr

Apr 21, 1912

• Born on 7th of October, 1885• Lived in the Netherlands• Theorised that the orbits of electrons in atoms have specific energy levels and along with that, also have specific values

Louis de Broglie

Apr 21, 1924

• Born on 5th of August, 1892• Lived in France• Theorised that electrons could behave as waves under some conditions, that they didn’t follow regular orbits like the solar system

Wolfgang Pauli

Apr 21, 1924

• Born of 25th of April, 1900• Lived in Switzerland• Created the Pauli Exclusion Principle that states that no two electrons in an atom can have the same four quantum numbers

Erwin Schrodinger

Apr 21, 1926

• Born on 12th of august, 1887• Lived in Switzerland • Discovered that electrons move in shells around the nucleus

Max Born

Apr 21, 1926

• Born 11th of December, 1882• Lived in Germany• Created a theory which states that the electron may exhibit the qualities of both a wave and a particle

Werner Heisenberg

Apr 21, 1927

• Born on 5th of December, 1901• Lived in Germany• Created the Uncertainty principle which the exact location and energy of an electron cannot be determine at the same time. Finding one or the other will mean uncertainty when trying to evaluate the other

Paul Dirac

Apr 21, 1928

• Born on 8th of August, 1902• Lived in America• Theorised about a positively charge electron

James Chadwick

Apr 21, 1932

• Born on 20th of October 1891• Lived in England• Discovered the neutron

Carl Anderson

Apr 21, 1932

• Born on 3rd of September, 1905• Lived in America• Discovered the postiron