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• Greek philosopher
• 460-370 B.C
• First to propose that matter was not infinitely divisible
Democritus
• English chemist & physicist
• 1766-1844
• Considered to be the father of our modern atomic theory
John Dalton
1. Proposed that matter could be explained in terms of “atoms”
from the Greek word “atomos,” meaning indivisible.
Dalton’s Atomic Theory (1803)
Page 64
In 1898 a scientist named J.J. Thomson conducted
experiments using a Crooke’s tube
(see figure 2.1 on p68)
• all elements give off the same negatively charged particles
• He called these particles “cathode ray particles”
Thomson concluded that...