ATOM

460 BC Democritus develops the idea of atoms

460

460 BC-he pounded up materials in his pestle and mortar until he had reduced them to smaller and smaller particles which he called

1808 John Dalton

Jan 14, 1808

suggested that all matter was made up of tiny spheres that were able to bounce around with perfect elasticity and called them

1898 Joseph John Thompson

Oct 14, 1898

found that atoms could sometimes eject a far smaller negative particle which he called an

1904 Thompson

Oct 14, 1904

Thompson develops the idea that an atom was made up of electrons scattered unevenly within an elastic sphere surrounded by a soup of positive charge to balance the electron's charge

1910 Ernest Rutherford

Oct 15, 1910

oversaw Geiger and Marsden carrying out his famous experiment. They fired Helium nuclei at a piece of gold foil which was only a few atoms thick. They found that although most of them passed through. About 1 in 10,000 hit