HONORS PHYSICAL SCIENCE
History of the Atom Timeline Research Guide
Initial Ideas – Greek Philosophers Democritus & Aristotle
 Who lived first? When?
 What were the two main concepts of Democritus’s theory about the nature of matter?
 What did Aristotle believe all matter was composed of?
The First Atomic Theory – John Dalton
 When did Dalton first propose his Atomic Theory?
 Dalton’s Atomic Theory was developed from three laws that were established regarding the
reaction of materials with one another. List those three laws and provide a short explanation.
 There are four key points to Dalton’s Atomic Theory (or five, depending on which source you use).
List them.
 Which parts of Dalton’s Atomic Theory do we know today are not true?
 Why is Dalton’s Atomic Theory called Dalton’s Atomic “Theory”, not Dalton’s Atomic “Law”?
A Major Breakthrough – Sir JJ Thomson
 What subatomic particle is Thomson credited with discovering?
 What piece of equipment did he use to make this discovery? Include a picture.
 When did he make his discovery?
 What facts did his experiments gather about this particle?
 How did Thomson’s discovery lead to major discoveries and developments in the structure of the
atom?
 What “model” of the atom did Thomson develop after his discovery?
The Next Major Breakthrough – Ernest Rutherford
 Which part of the atom is Rutherford credited with discovering?
 When did he make his discovery?
 Briefly describe the “Gold Foil Experiment” (the experiment Rutherford used to discover the
nucleus). Include a picture of the setup of the experiment and the equipment used.
 List three characteristics of the atom and/or the nucleus that Rutherford discovered during his
experiment.