Atomic Theory

Main

Democritus's Atom

400 BC

Aristole's Four Eleements

300 bc

Lavoisier proposes conservation of matter.

1787

Gay-Lussac discovers relation between temp and pressure.

1802

Dalton proposes atomic theory.

1803

Avogrado: equal volumes, pressure, and temp contain same number of molecules.

1811

Becquerel co-discovers radioactivity.

1897

Curie co-discovers radioactivity.

1897

Dalton discovers subatomic "electron."

1897

Planck presents quantum theory.

1900

Einstein presents theory of relativity.

1905

Geiger creates Geiger counter.

1908

Mardsen helps discover Nucleus and Geiger Counter.

1909

Millikan calculates mass of electron.

1909

Rutherford proposes nucleus.

1911

Bohr model applies quantum theory to atomic model.

1913

Mosely demonstrates importance of atomic number.

1913

Chadwick discovers the neutron.

1932