ATOMIC THEORY

DEMOCRITUS

ATOMOS THEORY

• Wondered if matter would eventually not be able to be smaller
• Named the smallest piece atomos meaning not to be cut
• Believed atomos were different sizes and shapes
• Believed atoms were infinite
• Atoms are always moving and could join together

ARISTOTLE

EARTH, WIND, FIRE, & WATER

• Was not right about the 4 elements
• Idea stuck around although it was wrong

DALTON

BILLIARD BALL MODEL

• Atoms can neither be created or destroyed
• Atoms are indivisible and indestructible
• Atoms are identical in mass and property
• Compounds are 2+ different atoms combined
• Chemical reactions are a rearrangement of atoms

JJ THOMSON

CATHODE RAY

• An atom is a positive charged sphere
• Has negatively charged electrons throughout it
• Equal number of positive and negative charges
• Atom is therefor neutral overall

CATHODE RAY

• Atom is therefor neutral overall

MILLIKAN

OIL DROP

• Found the charge of a single electron
• Also the size of an electron

RUTHERFORD

GOLD FOIL

• Figured out an atom has a nucleus
• Most of the mass is found in the nucleus
• The rest is mostly empty space

CHADWICK

PROTON NEUTRON

• Discovered neutron
• Neutron stabilizes the protons