The History of the Atom - Notes
The History of the Atom Chapter 5 Major Discoveries 1806: John Dalton Atomic theory 1896 Henri Becquerel Radioactivity 1897: JJ Thomson Discovered the Electron 1909: Robert Millikan Confirmed existence of Electrons, their mass and their negative charge 1910: Ernst Rutherford Nucleus has the protons and neutrons, rest is mostly empty space 1913: Neils Bohr Planetary model of the atom Dalton?s Atomic Theory Elements are made up of discrete units called atoms Atoms of each element are identical. Atoms of different elements are different. Compounds are formed when atoms combine. Each compound has a specific number and kinds of atom. Chemical reactions are rearrangement of atoms. Atoms are not created or destroyed. Becquerel and Radioactivity Discovered by accident