Download The Atomic Model - Mr. Brown`s Science Town

The Atomic Model
The 5 Stages of the
Atomic Model
Dalton’s Model
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The atom is a solid
indivisible mass
No protons, neutrons or
electrons
Like a marble
The Plum Pudding Model
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Developed by Lord
Kelvin based on the
work of J.J. Thomson
Negatively charged
electrons are
embedded in a positive
mass.
No protons or neutrons
The Nuclear Model
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Developed by
Rutherford
Based on his famous
“Gold Foil Experiment”
Results of experiment:
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Discovered nucleus =
positive dense core of
the atom containing
protons and neutrons
Atom is mostly empty
space where electrons
randomly orbit nucleus.
Rutherford’s Gold Foil Experiment
Planetary Model
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Developed by Neils
Bohr
Electrons travel in
circular, defined orbits
around nucleus called
energy levels
Energy level: region
around nucleus where
electrons are likely to
be moving
Like a target.
Quantum Mechanical Model
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Developed by Erwin Schrodinger
aka “Electron Cloud” model
Doesn’t define an exact path of electron;
estimates probability of finding electron in a
certain location
Uses atomic orbitals = a 3-D region around
nucleus that describes the electron’s
probable location.
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Each orbital can hold a maximum of 2 electrons