Atomic Theory
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Agenda
What do you know about the atom?
(whiteboard review)
Song – Atomic Theory Polka
Reading 4.2 & 4.3
Notes
What do you know about the atom?
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Who was Democritus?
What did he contribute to the model of the
atom?
Who came up with the atomic theory?
What were his four points?
Mn
manganese
scandium
Sc
Fe
iron
titanium
Ti
Co
cobalt
vanadium
V
Ni
nickel
chromium
Cr
Cu
copper
zinc
Zn
Song Time
Atomic Theory Polka
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Dalton, Thomson, Rutherford and Bohr.
Schrödinger and Heisenberg, and many, many
more. Used their brains to venture in the
realm of inner space and found the world of
the atom was a weird and wondrous place.
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Dalton did experiments and said, “I think it’s
clear, atoms are tiny indestructible spheres.”
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Thomson worked with cathode rays and said,
“I disagree. A plum-pudding model makes
much more sense to me.”
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A new chapter in atomic theory started to
unfold when Rutherford played around with
atoms made of gold. When a few of his alpha
particles came bounding back, he
hypothesized a nucleus had knocked them off
the track.
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Dalton, Thomson, Rutherford and Bohr.
Schrödinger and Heisenberg, and many, many
more. Used their brains to venture in the
realm of inner space and found the world of
the atom was a weird and wondrous place.
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Bohr saw spectral lines for hydrogen and said,
“It seems to me.. Electrons move in orbits
with specific energies.”
electron
neutron
proton
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Heisenberg said, “Forget it, there’s no way to
know the orbit or a path, where the electron’s
gonna go.”
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Schrödinger used lots and lots of fancy
mathematics, and made a model of the atom
based on quantum mechanics. It has orbitals
and those are based on probability. The atom
is a fuzzy blob of pure uncertainty.
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Dalton, Thomson, Rutherford and Bohr.
Schroedinger and Heisenburg, and many,
many more. Used their brains to venture in
the realm of inner space and found the world
of the atom was a weird and wondrous place.
Read 4.2 – 4.3 in a 6 inch voice
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Fill out the study guide as you read in
complete sentences.
Use your own words! It will help you to
remember more.
Atomic Theory Part II
Date:
JJ Thomson
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Found electron
Used cathode ray tube
“Plum Pudding” or “Chocolate Chip Cookies”
model
Robert Millikan
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Determined the electrical charge of electron
“Oil Drop Experiment”
Still plum pudding model
Eugen Goldstein
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Found the proton
Reverse cathode ray tube
Still plum pudding model
Ernest Rutherford
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Found nucleus
Gold foil experiment
Atom is mostly empty space – first nuclear model
James Chadwick
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Found neutron
Shot alpha particles at Be nucleus
Nucleus is made of two particles
Positive protons
 Neutral neutrons
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Niels Bohr
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Planetary model
Proposed electrons have a set amount of energy putting them
in different energy levels, or orbits around the nucleus.
Electrons can change energy levels; higher energy levels are
further from the nucleus.
electron
neutron
proton
Heisenberg’s uncertainty principle
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Heisenberg’s uncertainty principle: cannot
know exactly both the velocity and position of
electron at the same time.
Like trying to catch a helium balloon in the
dark.
Schrödinger
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Electron cloud gives a 90% probability of
finding the electron within the darkly shaded
area.
Electrons move like moths around a light –
unpredictable.
Homework
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Last element quiz FRIDAY! 