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430 BCE
Democritus
-Discovered the atom -
Dalton
-All matter is composed of atoms
-Atoms are indivisible and indestructible -
Thomson
-Discovered the electron using a cathode ray tube
-Proposed that atoms have negatively charged electrons embedded in a positively charged substance -
Rutherford
-Performed the gold foil experiment
-Discovered the nucleus
-Discovered that the nucleus contains the protons and neutrons of an atom -
Bohr
-Made the Bohr model
-Also called the planetary model because it depicts electrons orbiting around the nucleus of the atom -
Modern Atomic Theory
-Electron cloud model is the modern model of an atom
-says we cannot know exactly where an electron is at any given time