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Golden Valley HS • Chemistry
Name _______________________________
Period: ______________
3 • Electrons & Periodicity
Light & Quantum Mechanics – Notes 5
Relevant textbook pages: 372 - 382
Section Objectives
 Students will be able to calculate the wavelength, frequency or energy of light given two of these values.
 Students will be able to label a wave diagram identifying the wavelength, amplitude, trough and crest.
The physics of the very small
_______________________________________ explains how very small particles behave
• Quantum mechanics is an explanation for subatomic particles and atoms as waves
_______________________________________ describes the motions of bodies much larger
than atoms
Light
The study of light led to the development of the _______________________________________
Light is a kind of electromagnetic radiation.
Electromagnetic radiation includes many types: gamma rays, x-rays, radio waves…
Speed of light = 3.00 x 108 m/s, and is abbreviated “c”
All electromagnetic radiation travels at this same rate when measured in a ________________
Parts of a wave
Wavelength and Frequency
Are ________________related
• As one goes up the other goes ________________.
Different frequencies of light are different colors of light.
There is a wide variety of frequencies
The whole range is called a ________________
Wavelength Table
 Long wavelength = ________________________________________________________________
 Short wavelength = ________________________________________________________________
Atomic Spectra
________________light is made up of all the colors of the visible spectrum.
Passing it through a prism separates it.
If the light is not white
By heating a gas with electricity we can get it to give off ________________.
Passing this light through a prism does something different.
Atomic Spectrum
Each element gives off its own characteristic colors.
Can be used to identify the ________________.
S. Cool, 2009
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This is how we know what stars are made of.
Light is a Particle?
Energy is ________________.
Light is a form of ________________.
Therefore, light must be quantized
These smallest pieces of light are called ________________.
Photoelectric effect? Albert Einstein
Energy & frequency: directly related.
The energy (E ) of electromagnetic radiation is directly proportional to the frequency () of the
radiation.
E = h
Explanation of atomic spectra
When we write electron configurations, we are writing the lowest energy.
The energy level, and where the electron starts from, is called it’s ______________________the lowest energy level.
Changing the energy
Let’s look at a hydrogen atom, with only one electron, and in the first energy level.
Heat, electricity, or light can move the electron up to different energy levels. The electron is
now said to be “________________”
As the electron falls back to the ground state, it gives the energy back as ________________
They may fall down in specific steps
Each step has a different energy
What is light?
Light is a ________________- it comes in chunks.
Light is a ________________- we can measure its wavelength and it behaves as a wave
If we combine E=mc2 , c=, E = 1/2 mv2 and E = h,then we can get:
 = h/mv
(from Louis de Broglie)
called de Broglie’s equation
Calculates the wavelength of a particle.
Wave-Particle Duality
 J.J. Thomson won the Nobel prize for describing the electron as a ________________.
 His son, George Thomson won the Nobel prize for describing the ________________-like
nature of the electron.
Confused? You’ve Got Company!
S. Cool, 2009
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