Democritus, Aristotle, & John
Dalton
By: Allison Pucci, Carina D’Amato,
Mike Condon, Dan Skowronek,
Jessica Sampson
Who was Democritus?
• Greek philosopher (460-370 B.C)
• 1st person to propose the idea that matter
wasn’t infinitely divisible.
• acquired fame with his knowledge of
natural Phenomena, and predicted
weather change
• main interests: metaphysics, mathematics,
and astronomy
Democritus’ Theory
• expanded the atomic theory of Leucippus
• matter made up of tiny particle were called
atoms
• atoms couldn’t be created, destroyed, or further
divided
• had an idea, but couldn’t support his theory
• said the small pieces of matter that you couldn’t
divide any smaller were called atomos, which
means indivisible
Evidence on his Theory
• There was no evidence on Democritus’
theory because he couldn’t support his
theory.
Who was Aristotle?
• Greek philosopher (384-322 B.C.)
• Main interests: politics, metaphysics,
science, logic, and ethics
• Influences: Parmenides, Socrates, and
Plato
Aristotle’s Theory
Disagreed with Democritus’ idea of
matter
 Believed empty space didn’t exist
 Believed matter is made of earth, fire,
air, and water

Evidence of his Theory

Got everyone to believe it, but he had
no evidence
Who was John Dalton?
• School teacher in England; taught
Chemistry
• Lived from 1766-1844
• Thought about taking up law or medicine
• Recorded weather in his hometown
regularly
John Dalton’s Theory
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Ideas similar to Democritus
Took Democritus’ theory and tried proving it true
Dalton’s Atomic Theory (see handout)
Theory supports conservation of mass
However, not all of it was true
Thought that atoms couldn’t be broken down
into smaller parts (protons, neutrons, and
electrons)
• Didn’t know that atoms of an element could have
different properties (mass)
Evidence of his Theory
 Studied
numerous chemical reactions
 Made observations and measurements
along the way
 Able to determine the mass ratios of the
elements involved in those reactions
 Results are known as Dalton’s atomic
theory.
Citation Page

Buthelezi, Thandi, Laurel Dingrando, Nicholas Hainen, Cheryl
Wistrom, and Dinah Zike. Chemistry Matter and Change. New
York: Glencoe, 2008. 102-104.
 "Democritus." 20 Oct. 2007. Wikepedia. 21 Oct. 2007
<http://en.wikipedia.org/wiki/Democratus>.
 "John Dalton." Wikepedia. 19 Oct. 2007. Wikepedia. 21 Oct.
2007 <http://en.wikipedia.org/wiki/John_Dalton>.
 Anthony Carpi, Ph.D. "Matter: Atoms from Democritus to
Dalton," Visionlearning Vol. CHE-1 (1), 2003.
http://www.visionlearning.com/library/module_viewer.php?mid
=49