Erwin Schrodinger
• Quantum mechanics
– electrons can only exist in
specified energy states
• Electron cloud model
– orbital: region around the
nucleus where electrons
are likely to be found
Erwin Schrodinger
Electron Cloud Model (orbital)
• dots represent probability of finding an enot actual electrons
Schrodinger’s Cat
http://www.yout
ube.com/watch
?v=pNTMYNj2
Ulk
James Chadwick
• 1931
• Finds mass of Proton
•Irene Joliot Curie
•
•
1931
Finds Neutron
Glen Seaborg
• 1951
• Transuranic Elements
Electron Cloud Model
• Bohr was right about electrons moving
around the nucleus
• Wrong about them moving like a planet
in the solar system.
Electron Cloud
 An electron cloud is the model that shows most
likely where electrons are and their motions.
 Heisenberg Uncertainty Principle
◦ It is impossible to tell where an electron is at any
given moment.
 It is similar to a plane propeller moving. You can’t
really tell where the blade is exactly.
Electron Cloud Model
• Since we can’t know where an electron is, the
probable location of an electron is based on
how much energy the electron has.
• According to the modern atomic model, an
atom has a small positively charged nucleus
surrounded by a large region in which there
are enough electrons to make an atom
neutral.
Electron Cloud
• Electrons whirl about the
nucleus billions of times in one
second
• They are not moving around in
random patterns.
• Instead of energy levels as
Bohr predicted, the electrons
are found in an orbital region.
The electron can be anywhere
within that orbital, but it is
impossible to know where it is.