THE EVOLUTION OF ATOMIC THEORY

DEMOCRITUS

492 B.C

HIS ATOMIC THEORY

• Discovered that everything is made of atoms
• Believed that the atom was the smallest particle of matter
• His theory is sometimes just called "big thoughts"

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ARISTOTLE

EARTH, WIND, AND FIRE THEORY

• Provided an explanation to:
• Falling rocks
• Rising flame
• Circulation of air
• Showed to a extent how the natural world worked

DALTON

DALTON

BILLIARD BALL MODEL:

• Atoms make up all matter
• Atoms can't be divided,destroyed, or created
• Atoms of the same element are identical
• His theory stated that in chemical reach toons in atoms are neither created or destroyed

J.J THOMSON

PLUMB PUDDING MODEL

PLUMB PUDDING MODEL

• His mathematical model shows that electrons were organized in rotating rings
• He discovered the electron
• Describes electrons as plums surrounded in a cloud of pudding

MILLIKIN

OIL DROP THEORY

• Measures the charge of a single electron
• Is able to find the size along with charge of an atom
• Millikin received a Nobel prize for this discovery

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RUTHERFORD

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GOLD FOIL EXPERIMENT

• Positively charged electron model
• fire the beam of alpha particles on foil and watch the location the particles landed on the screen.
• Concluded that an atom was much more than just empty space and scattered electron
• Also found an atom must have a positively charged center that contains most of its mass

CHADWICK

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CHADWICK

• Discovered he neutron
• Won a Nobel prize
• James predicted the atom would have a neutron
• He established that atomic number is determined by the numbers of protons minus neutrons
• He also discovered the fourth subatomic particle,the neutron.

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