Do Now
 Indicate
The Uncertainty Principle
whether each of the
following electronic transitions:
 emits
energy, or
the absorption of energy
 requires
n
=3→n=1
n = 2 → n = 4
Do Now
n
=3→n=1
Emits
n
energy
=2→n=4
Absorbs
energy
The Uncertainty Principle
 In fact, all matter seems to have
both particle and wave properties!
 This is now known as:
 the
wave-particle duality of matter
The Wave Behavior of Matter
 The Bohr model does not work
for atoms with > 1 electron
 Since Thomson, electrons were
always thought to be particles
 It was later shown that electrons
also seem to have the properties
of a wave
The Uncertainty Principle
 He realized that the wave/particle
duality of matter places a limit on
how precisely we can know the
behavior of any microscopic
object
 The
German physicist Werner
Heisenberg discovered something
even stranger…
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The Uncertainty Principle
 Albert Einstein could never
accept Heisenberg’s discovery,
although, over time, Heisenberg
has been proven correct
 Here we see a rare instance of
where Albert Einstein was wrong!
The Uncertainty Principle
 This
idea, has become the basis
for the modern atomic model
 It is known as the Heisenberg
uncertainty principle
 The uncertainty principle is the
basis for quantum theory
The Uncertainty Principle
 The more precisely we know it’s
speed, the less precisely we know
its position
 The more precisely we know it’s
position, the less precisely we
know its speed
The Uncertainty Principle
 The uncertainty principle states
that it is impossible to know,
simultaneously:
exact speed, and
 the exact position
 the
any microscopic object, like an
electron
 of
The Modern Atomic Model
 In
modern atomic theory, we
don’t try to explain where the
electrons are – because you can’t!
 Being that the electron is
microscopic, we now think of it
as a wave, not as a particle
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The Uncertainty Principle
 The
result is a model that
describes the electron in terms of:
energy that it’s allowed to
have (quantized)
 It’s likely location in terms of
probability
 The
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