ATOMS TIMELINE

DEMOCRITUS 460BC

ATOMOS THEORY

• Atomos=indivisible
• First person to define an atom

ARISTOTLE 347 BC

EARTH,WIND,FIRE

• All matter is made up of all four elements.
• All elements are pure.
• Thought all 4 elements needed to be balanced.

DALTON 1803

BILLARD BALL

• Cannot be subdivided,created,or destroyed.
• Make up all matter.
• Combine with or separate from other Atoms.

JJ THOMSON 1897

PLUM PUDDING

• Believed hydrogen atom must be made up of more then 2 thousand electrons
• Thought it was a negative charge
• Must have some sort of positive charge.

RUTHERFORD 1919

+ NUCLEUS

• Radio activity
• numbers = # of protons
• Neutrons with no charge

MILIKAN 1908

MASS/CHARGE OF ELECTRON

• Electrons have a smaller mass then protons.
• Electron is not charged.
• Mass change of electron.

CHADWICK 1891

PROTON/NEUTRON

• Small positive charge.
• Came up with the word mass.
• Small negitive.