Bohr’s Model
Nucleus
Electron
Orbit
Energy Levels
Bohr Model of Atom
Increasing energy
of orbits
n=3
e-
n=2
e-
n=1
ee-
e-
e-
ee-
e-
e-
eA photon is emitted
with energy E = hf
The Bohr model of the atom, like many ideas in
the history of science, was at first prompted by
and later partially disproved by experimentation.
http://en.wikipedia.org/wiki/Category:Chemistry
An unsatisfactory model
for the hydrogen atom
According to classical physics, light
should be emitted as the electron
circles the nucleus. A loss of energy
would cause the electron to be drawn
closer to the nucleus and eventually
spiral into it.
Hill, Petrucci, General Chemistry An Integrated Approach 2nd Edition, page 294
Quantum Mechanical Model
Niels Bohr &
Albert Einstein
Modern atomic theory describes the
electronic structure of the atom as the
probability of finding electrons within certain
regions of space (orbitals).
Modern View
• The atom is mostly empty space
• Two regions
– Nucleus
• protons and neutrons
– Electron cloud
• region where you might find an electron