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REVISIT THE PHENOMENON
How do we know what
stars are made of?
CER
Claim, Evidence, Reasoning
Explain Your Reasoning
Revisit the claim you made when you encountered the
phenomenon. Summarize the evidence you gathered from your investigations and
research and finalize your Summary Table. Does your evidence support your claim?
If not, revise your claim. Explain why your evidence supports your claim.
STEM UNIT PROJECT
Now that you’ve completed the module, revisit your STEM unit project. You will
summarize your evidence and apply it to the project.
Module Wrap-Up
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THREE-DIMENSIONAL THINKING
GO FURTHER
Data Analysis Lab
What electron transitions account for the Balmer series?
Hydrogen’s emission spectrum comprises three series of
lines. Some wavelengths are ultraviolet (Lyman series) and
infrared (Paschen series). Visible wavelengths comprise the
Balmer series. The Bohr atomic model attributes these
spectral lines to transitions from higher-energy states with
electron orbits in which
n
=
n
i
to lower-energy states with
smaller electron orbits in which
n
=
n
f
.
CER
Analyze and Interpret Data
Some hydrogen balmer lines are designated H
α
(6562 Å),
H
β
(4861 Å), H
γ
(4340 Å), and H
δ
(4101 Å). Each wavelength (
λ
)
is related to an electron transition within a hydrogen atom by
the following equation, in which 1.09678
×
10
7
m
–
1
is known
as the Rydberg constant.
1 __
λ
=
1.09678
×
10
7
(
1 __
n
f
2
-
1 __
n
i
2
)
m
-
1
For hydrogen’s Balmer series, electron orbit transitions occur
from larger orbits to the
n
=
2 orbit; that is,
n
f
=
2.
CER
Analyze and Interpret Data
1.
Calculate
the wavelengths for the
following electron orbit transitions.
a.
n
i
=
3;
n
f
=
2
c.
n
i
=
5;
n
f
=
2
b.
n
i
=
4;
n
f
=
2
d.
n
i
=
6;
n
f
=
2
2.
Claim, Evidence, Reasoning
Relate
the Balmer-series wavelengths you
calculated in Question 1 to those
determined experimentally. Allowing
for experimental error and
calculation uncertainty, do the
wavelengths match? Explain your
answer. One angstrom (Å) equals
10
–
10
m.
3.
Apply
the formula
E
=
hc
/
λ
to
determine the energy per quantum
for each of the orbit transitions in
Question 1.
Module 4 • Electrons in Atoms
135