Transcript Atomic Theory PowerPoint

Unit 1: Atomic Structure
Honors Physical Science
Evolution of Atomic Theory
Democritus – 400 B.C.
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Greek Philosopher
Imagined particles
that were
indivisible
Constituents of
matter
Atom comes from
“atomos”
Opposed Aristotle
Aristotle – 350 B.C.
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Widely accepted
theory that all
matter can be
continually
divided.
Set science back
for thousands of
years.
Alchemy
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A pseudoscience that superceded
scientific discoveries.
Alchemists attempted to turn
metals into gold and developing the
“elixir” of life (able to cause
immortality and create life).
Pierre Gassendi - 1650
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Reintroduced
Particulate theory
No experimental
evidence
Supported by Sir
Isaac Newton
Antoine Lavoisier - 1778
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Developed Law of
Conservation of
Mass
Explained
combustion
Joseph Proust - 1799
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Developed “Proust’s
Law” using copper
oxide
Later renamed, the
Law of Definite
Proportions
Nearly discovered the
Law of multiple
proportions, but his
data used percentages
instead of weights.
John Dalton - 1802
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First to develop an
atomic theory. It
has 4 postulates.
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Each element is made
up of atoms
Atoms of the same
element are identical
in mass and
properties. Atoms of
different elements
differ in some way.
John Dalton - 1802
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Compounds are made
when atoms combine.
If elements combine
in more than one
whole number ratio,
the resulting
compound has
different properties
Chemical reactions
involve the
reorganization of
atoms.
Eugene Goldstein - 1886
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Discovered the proton using a
cathode ray tube.
J.J. Thomson - 1897
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Determined the
mass/charge ratio
of the electron.
5.69 x 10-9
Used the cathode
ray tube
Proposed a model
of the atom that
was mockingly
called the “plum
pudding” model
Robert Millikan - 1909
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Determined the
charge of the
electron using the
famous oil-drop
experiment
1.60 x 10-19
From this and
Thomson’s value,
the mass was
calculated to be
9.11 x 10-28g
Ernest Rutherford - 1911
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Performed the
famous gold foil
experiment
Determined 3
things
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The atom is mostly
empty space
The nucleus is
positively charged
The nucleus is a
small dense part of
the atom
Gold Foil Experiment
Gold Foil Experiment
Niels Bohr - 1913
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Observed spectral
lines for hydrogen
Proposed an orbit
theory of the
electron around
the atom.
Bohr Model
Hydrogen Spectrum
Louis De broglie - 1924
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Suggested that
matter could
exhibit wave
properties
Observed
diffraction patterns
in electrons
Erwin Schrödinger - 1926
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Developed a wave
equation.
Mathematical
function that
described the
nature of the
electron
James Chadwick - 1932
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Discovered the
neutron