Atoms and
The Periodic Table
KD McMahon
Reseda Science Magnet
Aristotle
and Democritus
Aristotle:
• Essence/Form
• Potential --> Actual
• Four Elements
Aristotle
and Democritus
Democritus
• a’ tome = not cut
• makes up everything
• many different kinds
• exist forever
• only matter
John Dalton
• Atoms of same element
are identical
• atoms combine --> whole #
ratios --> compounds
• chem Rx’s: atoms
separate & recombine
• no transmutation
Review Questions:
1. Why did Democritus call his fundamental particle of
matter the “atom?”
2. Why was Democritus’ theory rejected for so
many centuries?
3. Based on Dalton’s atomic theory what would be wrong
with the following formula for water: HO1/2
4. According to Dalton would it have been possible for
alchemists to have turned lead into gold?
JJ Thomson
Used cathode ray tubes
JJ Thomson
Used cathode with paddle wheel:
What did he conclude?
JJ Thomson
Used cathode with oppositely charged plates:
JJ Thomson
Used cathode with oppositely charged plates:
JJ Thomson
Used cathode with oppositely charged plates:
What did he conclude?
JJ Thomson
From these results he came up with:
The Plum Pudding Model
of the Atom