Democritus & Aristotle/
John Dalton
Democritus
• Democritus was alive 460 B.C. - 370
B.C.
• Was a Greek philosopher
• He had no formal education and
learned from his travels through out
Greece
Democritus's Theory
• hypothesized that all matter (plus
space and time) is composed of tiny
indestructible units, called atoms.
• His beliefs were amazingly ahead of
his time, but he could not answer
what holds atoms together and
therefore lost credibility
• *No Experiment*
Democritus
• Matter in empty
space that has a
different
appearance
• Atoms determine
properties
Aristotle
• Lived in 384 B.C. - 322 B.C.
• Was one of the most influential Greek
philosophers
• Was educated at the Plato academy in
Athens for nearly 20 years
Aristotle's Theory
• Belief: rejected Democritus' atomic theory,
and he especially didn't agree with the
theory that atoms more through empty
space, because he didn't believe empty
space exists.
• He was supported or considered more
credible than Democritus because he
already had a good reputation
• He did not believe that atoms exist but that
matter is made of earth, fire, air and water
• *No experiment*
Aristotle
• Diagram of
Aristotle's theory
John Dalton (1766-1844)
• School • English
Pardshow Hall
school
(a
Quaker
teacher
school)
• From the UK
Dalton's Theories
•
•
•
•
• Atoms of a specific element
are different from those of a
“Dalton's Atomic
different element.
Theory”
• Different atoms combine in
Matter is composed of
simple whole-number ratios
extremely small
to form compounds.
particles called atoms.
Atoms are indestructible • In a chemical reaction,
atoms are separated,
and indivisible.
combined or rearranged
Atoms of a given
element have the same
size, mass, and chemical
properties.
Dalton's experimental
design
• Law of definite
proportions
• And that all matter
is the same