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A Light in the Darkness
Introduction:
Background: Describe the concerns Bohr had about the Rutherford planetary model of the
atom. What did Bohr suggest might be the more accurate way of describing the motion or
behavior of the electron? Why did Bohr use the Ryberg equation to make his case? What
kinds of information does the Rydberg equation provide? What are the differences between a
continuous and emission spectrum? Mathematically, how would one describe a quantum leap?
[Place images of both spectra, here]
What is the Rydberg equation?
[Place the formula for the Rydberg equation, here]
Why did Bohr use the Ryberg equation to make his case? What kinds of information does the
Rydberg equation provide (this is an invitation to describe the equation in detail)?
Testable question: What assumptions and/or hypotheses are you going to use as a basis for
conducting this investigation? What is your rationale for making the assumptions and/or
hypotheses you did?
Design: How are you going to set up your investigation? What is your rationale for setting up
your protocol the way you did? Is this a controlled experiment? If so, what are the controlled
variables? If not…why not? How does a spectroscope work?
[Show schematic of spectroscope, here]
Analysis: How do you plan on using the equation to make sense of the results? More specifically,
what are your plans for re-arranging the equation for the purposes of data collection? What is
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your rationale for re-arranging the equation? What assumptions are you going to make in
analyzing the data (be specific)?
[Show the re-arranged equation and associated expressions, here]
The recommendation at this point is to use the ultraviolet data and graphical results provided with
the pre-lab reading to make your case.
[Show any relevant emission spectra, graphs and sample data, here]
Results:
Suggested table for recording results:
Hydrogen
Observed
color
of emission
line
Observed
Wavelength
(λ)
Reported color
of emission line
Observed
Wavelength
(λ)
% error
|𝑒𝑥𝑝 − 𝑟𝑒𝑝|
𝑥 100
𝑟𝑒𝑝
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Helium
Observed
color
of emission
line
Observed
Wavelength
(λ)
Reported color
of emission line
Observed
Wavelength
(λ)
% error
|𝑒𝑥𝑝 − 𝑟𝑒𝑝|
𝑥 100
𝑟𝑒𝑝
Narrative: Provide a short summary of the observed results.
Discussion:
Restatement and Data Analysis: Restate the assumptions and/or hypotheses used in this
investigation. Briefly review how the data was analyzed.
[ Place tables, here]
Hydrogen
ni values
1
𝑛𝑖 2
For the value n = 1 (1st quantum energy level)
λ (nm)
1
λ
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Helium
1
𝑛𝑖 2
ni values
λ (nm)
1
λ
For the value n = 2 (2st quantum energy level)
[ Place graphs, here]
Hydrogen:
1 graph showing the raw data (ni values, λ (nm))
1 graph (
1 1
𝑛𝑖 2 , λ
1 1
) based upon nf =1, 1 graph (𝑛𝑖2 , λ) based upon nf =2
`
Helium:
1 graph showing the raw data
1 graph based upon nf =1, 1 graph based upon nf =2
Interpretation: What were the differences between the hydrogen and helium spectra? What kinds
of regressions for the hydrogen and helium were supported by the data? Based upon these
regressions, what did you determine to be the Rydberg constant (R)? How does this value
correlate to the reported value for R (1.09737 x 107 m-1)? Using the wavelengths you observed
for hydrogen, what were the calculated ni values for each of the emission lines? How do these
values compare to the ni values that were a part of your hypotheses? Which of your hypotheses
concerning hydrogen will you be rejecting?
How do the regression lines for hydrogen and helium differ? If they are not the same, what would
account for their differences? Based upon your results with the Rydberg equation, what might
one say concerning the Bohr model of the atom?