Evalution of the Atom!!!

Democritus

101

Greece - stated that all matter is made up of atoms. He also stated that atoms are eternal and invisible and so small that they can’t be divided, and they entirely fill up the space they’re in.

Aristotle

350

Greece - provided the method of gathering scientific facts, which proved as the basis for all scientific work.

John Dalton

Oct 9, 1803

England - formed the atomic theory, which states that all matter is composed of tiny, indestructible particles called atoms that are all alike and have the same atomic weight.

crookes

Oct 9, 1870

England - created the Crookes’ tube and demonstrated that cathode rays travel in straight lines and produce phosphorescence and heat when they strike certain materials.

J.J Thomson

Oct 9, 1898

England - discovered the electron and developed the plum-pudding model of the atom

Robert Millikan

Oct 9, 1908

USA - found out the electric charge of the electron

Ernest Rutherford

Oct 9, 1909

England - used the results of his gold-foil experiment to state that all the mass of an atom were in a small positively-charged ball at the center of the atom.

Neils Bohr

Oct 9, 1913

Denmark - stated that the electrons moved around the nucleus in successively large orbits. He also presented the Bohr atomic model which stated that atoms absorb or emit radiation only when the electrons abruptly jump between allowed, or stationary, states.

Chadwick

Oct 9, 1931

England - discovered the neutrally-charged neutron.

Werner Heisenberg

Oct 10, 1932

For this theory and the applications of it which resulted especially in the discovery of allotropic forms of hydrogen, Heisenberg was awarded the Nobel Prize for Physics for 1932.

Otto Hahn

Oct 9, 1938

Germany - discovered nuclear fission, in which the nucleus of an atom breaks up into two separate nuclei, while experimenting with uranium.