ATOMIC THEORY PROGRESSION

DEMOCRITUS

ATOMOS

• Idea that everything is made up of atoms
• Infinite sizes, shapes, etc.
• Indivisible

ARISTOTLE

FOUR eLEMENTS

• All substances made up of 4 elements
• Earth, Wind, Fire, Water
• Theory survived for over 2000 years

JOHN DALTON

BILLIARD BALL MODEL

• Atom = smallest part of element
• Cannot be divided
• Atoms make up all matter
• Similar to a billiard ball

J.J. THOMSON

PLUM PUDDING MODEL

• Cathode Ray experiment
• Atom is made of electrons
• Positively charged "pudding"
• Negatively charged "plums"
• Plums = electrons

ERNEST RUTHERFORD

GOLD FOIL EXPERIMENT

• Disproved Thomson's theory
• Discovered nucleus
• Nucleus is positively charged
• Atom isn't made up of one particle

ROBERT A. MILLIKAN

OIL DROP EXPERIMENT

• Dropped oil between two electrodes
• Found the charge of an electron
• Able to find the mass as well

JAMES CHADWICK

PROTON-NEUTRON MODEL

• Discovery of neutrons
• Nucleus is made of protons and neutrons
• Neutrons have neutral charge