CH202 Study Guide - Final Guide: Niels Bohr, Bohr Model
The Bohr Model
The most important properties of atomic and molecular
structure may be exemplified using a simplified picture
of an atom that is called the Bohr Model. This model was
proposed by Niels Bohr in 1915; it is not completely
correct, but it has many features that are approximately
correct and it is sufficient for much of our discussion.
The correct theory of the atom is called quantum
mechanics; the Bohr Model is an approximation to
quantum mechanics that has the virtue of being much
simpler.
The Bohr Model is probably familar as the "planetary
model" of the atom illustrated in the adjacent figure
that, for example, is used as a symbol for atomic energy
(a bit of a misnomer, since the energy in "atomic energy"
is actually the energy of the nucleus, rather than the
entire atom). In the Bohr Model the neutrons and
protons (symbolized by red and blue balls in the
adjacent image) occupy a dense central region called the
nucleus, and the electrons orbit the nucleus much like
planets orbiting the Sun (but the orbits are not confined
to a plane as is approximately true in the Solar System).
The adjacent image is not to scale since in the realistic
case the radius of the nucleus is about 100,000 times
smaller than the radius of the entire atom, and as far as
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