ATOMIC THEORY TIMELINE

DEMOCRITUS

• Year of work 460 BC- 370 BC

DEMOCRITUS

• He formed the Atomos model
• His theory was that everything is composed of atoms.
• Also said that atoms were physically indivisble
• And the atoms themselves are indestructible

ARISTOTLE

ARISTOTLE

• Thought everything was made up of earth, wind, fire, and water.
• Felt that matter could always be divided into smaller matter.
• This view held for 2,000 years.

DALTON

DALTONS BILLIARD BALL MODEL

• His atomic model was that an atom was like a billiard ball.
• That an atom was a solid indivisble sphere.
• Also thought that everything is made of atoms.
• And that atoms were indivisble and indestructible.

THOMSON

THOMSONS ATOMIC THEORY

• He made the plum pudding model
• Thought that an atom was electrons( negative charge) were surrounded by positive charged matter
• Didn't think there was a nucleus.
• Did the cathode ray experiment

RUTHERFORD

RUTHERFORD

• Did the famous gold foil experiment
• He did the positively charged nucleus model
• Thought that the nucleus was made of one positive charge
• And surrounded by negative charged electrons

MILLIKAN

MILLIKAN

• Did the oil drop experiment
• Found the equation of mass to charge of electron.
• Proved thomsons hypothesis that the mass of an electron is 1,000 times smaller than the lightest atom.
• Determined that electron charge was a single value, and same value for all forms of electricity.

CHADWICK

CHADWICK

• Rutherford had the idea that there was a particle with no charge called a neutron but he had no evidence.
• Chadwick proved that there really was a neutron.
• Received the nobel prize for his discovery in 1935
• Found this out with his proton-neutron model.