Chemistry Timeline

Events

Democritus

465 B.C

His hypothesis was that atoms can not Be destroyed, differ in size, shape, and temperature, are always moving and are invisible. He believed infinate number of atoms.

John Dalton

1766

Elements are made of really small particles called atoms. Atoms of a given element are identical in size, mass and other properties.

Dmitri Mendeleev

1869

Periodic law- he noticed patterns between elements and then graphed them and arranged by atomic weight.

Eugene Goldstein

1870

Discovered electrical discharge tubes and discovered anode rays.

J. J. Thomson

1897

Showed that cathode rays were composed of negatively charged particles.

Marie Curie

1898

Published evidence supporting the existence of Radium

Marie Curie

1902

Isolated a sample of Radium

Ernest Rutherford

1907

Proved that alpha radiation is helium nuclei.

Robert Millikan

1913

Conducted the oil drop experiment that studied the charge of an atom.

Niels Bohr

1913

Developed and published his model of atomic structure

Marie Curie

1914

Sent out the first X-ray machines for World War I

Erwin Schrödinger

1926

Generated a mathematical model for the distribution of electrons in an atom, known as wavelengths.