Transcript Section 4.1

Section 4.1
Early Theories of
Matter
Four Components of Matter
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Early Greek philosophers associated properties
of matter with Water, Earth, Air, and Fire.
They thought matter was infinitely divisible
This incorrect belief lasted until the 1800s.
Democritus
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Greek philosopher (460-370 B.C.)
First to propose matter was NOT
infinitely divisible
Atomos- indestructible particles
Democritus’s Ideas
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Matter is composed of empty space
Atoms are solid, homogeneous, invisible particles
Different kinds of atoms have different shapes and
sizes
Differing properties of matter come from the
different shapes and sizes of atoms.
Changes in matter come from changes in grouping
of atoms
Aristotle
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Criticized Democritus’s ideas
about atoms.
Invisible particles do not
exist- No Atoms!
Accepted view for 2,000
years
John Dalton
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1766-1844
School teacher from England
Revived Democritus’s ideas about atoms
Developed the modern atomic theory based on
scientific research of the time.
Dalton’s Atomic Theory
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All matter is composed of extremely small particles
called atoms
All atoms of an element are identical and specific to
that element only.
Atoms cannot be created, divided, or destroyed
Different atoms combine in simple whole-number ratios
to form compounds.
In a chemical reaction, atoms are separated,
combined, or rearranged.
Atom
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Smallest particle of an element that retains the
properties of that element
World Population =
6,000,000,000
Atoms in a Penny= 29,000,000,000,000,000,000,000
Homework
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1-5 on page 91
Must write in COMPLETE sentences in order
to get credit!!!
Will be collected tomorrow