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Real Bohring Spectra
APPLYING YOUR ENERGY MODEL TO BOHR’S MODEL OF THE ATOM
Application I
Problem
What do we have to do to our energy model of the atom to make it fit with Bohr’s model of the
atom? You will use the Spectroscopy Lab Suite with some new rules to create an energy model
of an atom that explains the spectra of an unknown gas.
Materials
VQM web program, Computer.
Procedures
1. Open Safari and open the pull down safari menu bar and drag down to VQM. the Gas Lamp
Emission Spectroscopy computer program by clicking on “Emission” under Spectroscopy
Lab Suite, Gas Lamp. Place the unknown gas tube in the gas lamp socket. If you are doing
this at home go to http://web.phys.ksu.edu/vqm/software/online/vqm/index.html.
2. When the unknown is in the socket, you can create your own spectrum. Click on the Edit
button. Select eV for your units. Type in the following energy values: 1.59 eV, 2.05 eV,
2.71 eV, 3.11 eV and 0 for the computer-generated spectral pattern that will appear on the top
black screen. This pattern will illustrate the spectrum emitted by some unknown gas.
3. Create an energy level diagram for this unknown gas by using the following rules:
I. In an actual lab experiment with your element, ultraviolet light was detected. The
lowest UV energy you can have was identified as being 3.11 eV. Additional UV light
may exist.
II. The lab also identified the most energetic infrared light as being 1.59 eV. The most IR
energy you can have was identified as being 1.59 eV. Additional IR light may exist.
III. Only two spectral lines were visible at 2.05 and 2.71 eV, so you cannot have any
additional visible lines than these two.
IV. Transitions may skip energy levels.
V. Energy levels get closer to each other as they move up the energy level diagram.
VI. The energy levels must fit on the screen. No energy level can be placed at 0 eV. Recall
that an electron with 0 total energy represents the situation in which an electron is not
interacting with the atom and has no kinetic or potential energy. In addition, one
energy level must be placed at –10 eV which represents the lowest energy level (ground
state) for an electron bound to an atom of our unknown gas.
4. Construct an energy level model for the unknown gas that does not violate any of the rules
listed above.
5. Sketch or print out the resulting energy level diagram. Your diagram should include the
energy levels, their respective energies, and resulting transitions. Identify the transition(s)
that are associated with the specific spectral lines given.
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Summing Up
1. On your energy level diagram, identify and label all
Table 1: Range of Energies for
Various Colors of Light (eV)
transition(s) that are possible. Use Table 1 (which shows
the ranges of energy values for the various colors of light) to
Infrared
< 1.6 eV
determine the resulting type of light predicted.
red
1.6 – 2.0
2. Bohr’s model of the atom considers the simplest atom – the orange
2.0 – 2.1
hydrogen atom in which a single electron travels in a closed yellow
2.1 – 2.3
2.3 – 2.6
orbit around a positively-charged nucleus. The lowest green
blue
2.6 – 2.8
energy level (called the ground state) corresponds to –13.6
violet
2.8 – 3.1
eV. In order for an electron from the ground state to gain Ultraviolet
> 3.1 eV
enough energy to no longer be attached to the hydrogen
atom, it would have to absorb a photon of 13.6 eV or more.
What energy would be required to free an electron from each of the energy levels you
identified in your model?
3.
The five lowest allowed energy levels for Bohr’s hydrogen atom is illustrated below. Identify
all transition(s) that are possible. Use Table 1 to determine the resulting type of light
predicted for Bohr’s model.
n=5
n=4
E5 = -.544 eV
E4 = -.85 eV
n=3
E3 = -1.51 eV
n=2
E2 = -3.25 eV
n=1
E1 = -13.6 eV
Activity Extension:
1. Use the Gas Lamp Emission Spectroscopy computer program to create your own energy level
model for an unknown. This unknown can be unique.
2. Decide on the amount of energy necessary for an electron at the ground state to no longer be
attached to the atom.
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3. Next, determine what type of light will be detected. Type in appropriate energy values for
your unknown to fit on the computer screen. Have your partner see if he/she can determine
what you had in mind.
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