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Topics for the day
•
Administrative stuff
•
Quantum mechanics
•
One dimensional particle in a box
•
The hydrogen atom
•
Quantum numbers
•
Electronic orbitals
Administrative stuff
Wednesday is Twelfth class day. By then you must have:
Add/dropped the class
Filled in the exam makeup form if you need any makeups
Finished the initial ALEKS assessment
Provided letters for accommodations, religious holidays.
..
So far, 29 of you have started HW One on Quest (due Fri)
and 19 have started the Coursework ALEKS (due Fri week)
Sample Exam One will be posted on Quest later today.
What’s on the exam?
Revision of prerequisite knowledge
Textbook chapters 1–4
ALEKS preparatory chemistry assessment
Quest homework
Quantum mechanics and the atom
Textbook chapter 12
ALEKS course homework, objective 1
Quest homework
Lecture clicker questions and worked problems
1
2
3
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E
∞
=0
Emission
•
E
∞
= 0, and as n becomes smaller, E is lower,
thus all the energy levels must be negative.
Δ
E
= E
1
– E
2
= h
ν
Δ
E = h
ν
= E
2
– E
1
•
When an electron makes a
transition
from a lower n to a higher n level, the
difference in energy comes from a photon:
Absorption
In the case of absorption, we also say that
the photon has
excited
the electron.
•
When an electron makes a
transition
from a higher n to a lower n level, the
difference in energy is lost as a photon:
Emission
Absorption
Where were we?
A.
n=4
→
n=2
B.
n=4
→
n=1
C.
n=3
→
n=1
D.
n=4
→
n=3
E.
n=2
→
n=1
iClicker Time
An electron in a H atom could undergo any
of these transitions by emitting light. Which
transition would give light of the shortest
wavelength?
Does this energy level diagram help?
Δ
E = h
ν
=
λ
hc
Shortest
λ
㱺
Largest E
•
The Heisenberg uncertainty principles shows us that there is a
fundamental limit to how well we can “know” certain properties.
•
We saw from a calculation that the size of the uncertainty in
electron position is similar to the size of an atom.
So we don’t know for sure exactly where those electrons are!
•
If we can’t say where exactly an electron is, it seems unlikely that
it will be in a welldeFned circular orbit around the nucleus.
•
We will start talking about
probability distributions
to
describe the location of an election, meaning identifying areas
where the probability is high that the electron may be there.
4
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This note was uploaded on 03/06/2010 for the course CHEM 52375 taught by Professor Shear during the Spring '10 term at University of TexasTyler.
 Spring '10
 shear
 Electron

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