review of atomic and quantum theory pre einstein…. light exhibits wave characteristics -...
TRANSCRIPT
Review of Atomic and Quantum Theory
Pre Einstein….
Light exhibits Wave Characteristics - Electromagnetic Spectrum, Theory of “Ether”
Line Emission Spectrum, Photoelectric Effect - Light/Electrons show Particle Characteristics
WAVES PARTICLES
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http://www.hetemeel.com/einsteinform.php
Bohr’s Model of the Atom
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kosmoi.com/Science/ Physics/Quantum/
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library.thinkquest.org
Bohr Model of Atom Electrons can only occupy specific “orbits”
Explains Line Emission Spectrums & Quantum Levels
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Electrons show PARTICLE characteristics
The Swinging Pendulum…
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www.blazelabs.com/ f-p-prop.asp
DeBroglie - Explained “particle” nature of Line Emissions with mathematical equations for WAVES.
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http://dbhs.wvusd.k12.ca.us/webdocs/Gallery/Gallery5.html
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Light/Electrons show WAVE properties
Light/Electrons show PARTICLE properties
Remember the Interference Patterns of Waves at Station 4?
www.sr.bham.ac.uk/ xmm/diffpage1.html
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This is a photograph of an a beam of electrons passed through a substance.
This is a picture of light being “confined” in a telescope.
DeBroglie: A “confined wave”, acts similarly to particles.
http://dbhs.wvusd.k12.ca.us/webdocs/Gallery/Gallery15.html
So Where Are They? The Heisenberg Uncertainty Principle
•Electrons are particles that can be described in terms of BOTH waves and PARTICLES.•If you know where the electron is, then you can’t determine its speed or direction.
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OBSERVATION changes the behavior of the electron
If you know the electrons speed and direction, you don’t know where the electron is.
Schrodinger
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www.malaspina.org
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digg.com/general_sciences/ e=mc%C2%B2_explained
Schrodinger developed complex mathematical equations using “quantum numbers “ to describe what Bohr observed but his equations described WAVES not particles.
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boomeria.org/chemlectures/orbitals/orbitals.html
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Wait a minute… I don’t buy this! “God does not throw dice!
http://www.biografiasyvidas.com/monografia/einstein/fotos/einstein_1947.jpg
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http://boomeria.org/chemlectures/orbitals/orbitals.html
When Schrodinger put his “quantum numbers” in his equations, mathematically he could calculate the energy levels that Bohr explained with his “planetary” model of the atom.
Quantum Energy Levels
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Energy Levels
Quantum Number “n”Quantum “shapes” (sublevel) (Quantum Number “l”)
Orbitals
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http://boomeria.org/chemlectures/orbitals/shapeclouds.jpg
Electron Orbitals Example
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http://fig.cox.miami.edu/~cmallery/150/chemistry/c2x11orbitals.jpg
D Orbitals
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http://www4.nau.edu/microanalysis/Microprobe/img/orbital.jpg
1 Dimensional View of Orbitals
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www.answers.com/ topic/quantum-mechan
Actual Electron Cloud
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Image of the electron cloud around a nickle impurity in a high-temperature superconductor, obtained with a scanning tunneling microscope. The central spot is the nickle atom, surrounded by a cloverleaf pattern whose fourfold symmetry is indicative of the underlying d-wave nature of the high-temperature superconducting state.PHOTO CREDIT: Seamus Davis/UC Berkeley
http://www.berkeley.edu/news/media/releases/2001/06/20_physc.html
Electron Configurations
Definition - The arrangement of the electrons in an atom.
• unique to each atom
• tend to assume arrangements that have the lowest possible energy levels
“Ground State Configuration” Defenition -
Lowest Energy State arrangement
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http://hi.fi.tripod.com/timeline/images/electron_cloud.jpg
Rules for Defining Electon Configurations
• Aufbau Principle - an electron occupies the lowest-energy orbital
•Pauli Exclusion Principle - No two electrons in the same atom can have the same set of 4 quantum numbers.
•Hunds Rule - orbitals of equal energy have one electron before a second electron is added, and spin direction is the same for single electrons in that energy level.
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How are Electron Configurations Written
•Energy Level Comes First…
•Shape Comes Second…
•Number of Electrons in the shape comes Third as a superscript…
•Spin is “implied by # of electrons
“1”, “2”, etc.
“1s”, “2s”, “2p”, etc.
“1s1”, “1s2”, “2s1” , etc.
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http://www.beyondbooks.com/psc92/images/00080041.jpg
Practical Application
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Start with Hydrogen…
• Hydrogen has one electron.
•Lowest Energy Level is “1”
•Lowest Energy Shape is “spherical”
Lowest Energry Level
So… electron configuration will be “1s”
Practical Application - Helium
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Helium has 2 electrons
•Lowest Energy Level is “1”
•Lowest Energy Shape is “spherical”
•Two electrons will occupy orbital with different “spins”
Lowest Energry Level
So… electron configuration will be “1s2”
Electron Configuration Handout
Write the Electron Configuration for
Hydrogen:
Helium:
1s
2s 2p3s
3p
3d4s
1s
1s2
Practical Application - Lithium
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Lithium has 3 electrons
•Lowest Energy Level is “1”
•Lowest Energy Shape is “spherical”
•Two electrons will occupy orbital with different “spins”
•Next lowest Energy State is level “2”
•The Lowest Energy Shape at level “2” is spherical
So… electron configuration will be “1s22s”
Lowest Energy State
Second Lowest Energy
State
Noble Gas Nomenclature
•When you get to a “Noble Gas”, the electrons fill up all the orbitals on that energy level.
•You can now describe those electrons with the designation of the Noble Gas in “[brackets]”
•Example…Lithium can be described as 1s22s or [He]2s since it has all the electrons for Helium plus one more.
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Practical Application - Beryllium
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Beryllium has 4 electrons…
•Beryllium fills up all of the orbitals for “Lithium” then…
•Adds an additional electron to the same spherical shape as the one Lithium used last
So… electron configuration will be “1s22s2”
Lowest Energy State
Second Lowest Energy
State
Practical Application - Boron
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Boron has 5 electrons…
•Boron fills up all of the orbitals for “Beryllium” then…
•Uses a new shape, but same energy level. The “p” “shape” can hold up to 6 electrons because of the 3 dimensional orientation.
•Remember, to NEXT put electrons in each 3 dimensional section of the orbital before putting two together. What rule would this relate to?So… electron configuration will be “1s22s22p”
Lowest Energy State
Second Lowest Energy
State
Same Energy
Level, different
shape
Electron Configuration Handout
1s
2s 2p3s
3p
3d4s
Practical Application - Carbon, Nitrogen, Oxygen, Flourine, Neon
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Carbon has 6 electrons
So… electron configuration will be “1s22s22p2”
•Nitrogen has 7 electronsSo… electron configuration will be “1s22s22p3”
What are the electron configurations for Oxygen, Flourine and Neon?
Lowest Energy State
Second Lowest Energy
State
Same Energy
Level, different
shape
Electron Configuration Handout
1s
2s 2p3s
3p
3d4s
Now we are at Argon… What next?
Notice that the next lowest energy level is not “3d” but “4s”!
Sometimes different shapes have different energy levels than are “lower” than the Quantum number level.
So the electron configuration added for Potassium starts at “4s”