atomic history timeline

Democritus

400 BCE

Said that matter was made up of smaller particles called "Atoms"

John Dalton

1808

Dalton said that the atom was a solid, indivisible mass. he also came up with the atomic theory

Michael Faraday

1865

He was a chemist that worked with electricity. He wrote a manual of practical chemistry and discovered a number of new organic compounds

JJ. Thomas

1897

Thomas used the Cathode ray tube and magnets to discover that atoms have negative charges called electrons. he thought the electrons were scattered throughout the atom. he model was called the plum pudding model

Millikan

1909

determined the exact electric charge of electrons by doing a series of of oil drop experiments.

Rutherford

1910

He discovered the nucleus of the atom using the gold foil experiment and said that most of the atom was space where the electrons are scattered

Bohr

1913

Bohr said that electrons orbited the nucleus at different energy levels.

Erwin Schrodinger

1926

He said that electrons were not orbiting the nucleus in set paths, rather they are located in a "cloud" around the nucleus. he came up with the Quantum Mechanical Model.

James Chadwick

1932

Chadwick proved the existence of neutrons and said that they have no charge.

Deep dive on James Chadwick

1935

James Chadwick was born in 1891, Manchester England. He received his doctorate in 1921 and started studying the transmutation of elements and the nature of the atomic nucleus. He later worked on the Manhattan Project for the development of the atomic bomb. After they created the atomic bomb he expressed guilt but said that it was inevitable.