Transcript Quantum Theory

As an object gets hot, it gives
Off energy in the form of
Electromagnetic radiation.
Blackbody radiation is the
Electromagnetic radiation
Emitted by a blackbody, which
Absorbs all incoming radiation and
Then emits radiation based
Only on its temperature.
Classical physics cannot account
For blackbody radiation.
The ultraviolet catastrophe is
The contradiction between the
Predictions of classical physics
And the experimental data for
The electromagnetic radiation
Of a blackbody in the
Ultraviolet end of the spectrum.
Experimental data for blackbody
Radiation support the quantization
Of energy.
Quantization was discovered by
Max Planck at the beginning
Of the 20th century.
A quanta is a packet of energy.
Atoms can only give off, or absorb
Energy by units of quanta.
After many experiments and
Calculations, he discovered
E=hf
energy
Planck’s
Constant
6.626 X 10-34 J*s
frequency
The pendulum of a clock swings
Back and forth with a frequency
Of 2 Hz. How much energy would
Be carried away in one quantum?
E = 1.3 X 10-33
Classical physics cannot explain
The photoelectric effect.
The photoelectric effect is the
Emission of electrons from a
Surface that occurs when light
Of certain frequencies
Shines on the surface.
In photoelectric effect, electrons
Are ejected from the surface of a
Metal when light shines
On that metal.
Discovered by Einstein
The stopping potential of a certain
Photocell is 4 V. What is the kinetic
Energy given to the electrons by
Incident light? Give your answer
In Joules and Electron Volts.
6.4 x 10-19 J
4.0 eV
Einstein used Planck’s idea
To say that light also behaved
With quanta.
These “quanta” are called photons.
This is called the wave-particle
Duality of light.
The Compton shift supports the
Photon theory of light.
The Compton shift is the change
In wavelength between incoming
And scattered electromagnetic
Waves.
The photoelectric effect is the
Reason why there is sound
During a movie.
If energy has a dual nature,
How about matter?
Louis de Broglie thought so.
He referred to the wavelike
Behavior of particles matter waves.
De Broglie was awarded the
Nobel Prize for his work.
The wavelength of matter
Waves depends on the momentum.
h
λ=
mv
The frequency of matter waves
Depends on energy.
E
f=
h
What is the de Broglie wavelength
Of a 50 g rock with a speed
Of 40 m/s?
λ = 3.32 X 10-34
In 1927 Werner Heisenberg
Proposed his uncertainty
Principle.
His principle states that the
Position and the momentum of
A moving object cannot
Simultaneously known.
Attempting to locate an
Electron will change the way
It is moving.
The density of an electron cloud
Is called electron density.
Electron clouds are dense where
The probability of finding an
Electron is great.
An atomic orbital is a region
Around the nucleus of an atom
Where an electron is likely to
Be found.
There are several different kinds of
Orbitals, each having a different
Fundamental shape.
Einstein was one of the founders
Of quantum theory, but he did
Not want to believe that
Probability was the final
Description of nature.
He said “ In any case, I am
Convinced that God does not
Play dice.”