ATOMIC THEORY TIMELINE

DEMOCRITUS 400 BC

ATOMOS THEORY

• States that all matter is made of atoms.
• Atomos is greek for Uncuttable.
• Democritus was the first to come up with the theory.

ARISTOTLE 383-322 BCE

EARTH WIND FIRE WATER, AND AETHER?

• Thought everything was made of these elements
• Proposed fith element: aether
• Aether supposedly makes up stars and planets

JOHN DALTON 1808

BILLIARD BALL MODEL

• Created a basic model of the atom.
• It proposed that atoms are the smallest particle of an element.
• Also they combine with or break away from other atoms to form compounds

J.J THOMSON 1904

PLUM PUDDING MODEL

• Said atoms are made of electrons.
• Positive charge to balance electorns.
• Negative chars plums surrounded by positive pudding.

CATHODE RAYS

• Vacuum tube with electron gun and fluroscent screen used to view images.
• Disvovered electron.
• Also found isotopes.

ERNEST RUTHERFORD

GOLD FOIL EXPERIMENT

• Studied the absorption of radioactivity by thin sheets of metal foil
• Three types of radiation. Alpha beta gamma.
• New structure of atom.

ROBERT MILLIKAN

OIL DROP

• Charged oil droplets.
• Gravitational pull and upward drag.
• Single electron.

JAMES CHADWICK

JAMES CHADWICK

• Bombarded alpha particles.
• Discovered neutron