Spectroscopy Tool Lab Report
Directions: Use this worksheet as you complete Parts 1 and 2 of the Spectroscopy
Tool Lab. In Part 1: Emission Spectra, you will investigate light patterns
produced by the elements. In Part 2: Stellar Spectra, you will analyze emission
and absorption spectra of stars to draw conclusions about their composition. This
lab report will be submitted for your portfolio assignment.
Part 1. Emission Spectra
Background
An emission spectrum shows the wavelengths (and frequencies) of electromagnetic
radiation emitted by an element during its transition from a high energy state to a
low energy state. Spectroscopes typically analyze energized gases. Elemental gases
produce unique patterns of colored light lines because each one has a unique
number of electrons organized into atomic energy levels.
There are many practical uses for spectroscopy. Consider a fluorescent bulb
company that discovers a leaking gas in its laboratory. The company uses a variety
of gases in its bulbs, such as hydrogen, helium, argon, neon, xenon, krypton, and
even mercury vapor at very low pressure.
The company must identify the gas in order to choose the safest method for
decontaminating the lab. Scientists gather a sample of the leaking gas into a
spectroscopy tube. They excite the gas and capture its spectrum, shown below.
In this part of the lab, you will analyze emission spectra of the elements to help the
scientists identify the unknown gas.
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Investigate
Follow these steps to help the chemical company identify the gas leaking into the
lab:
1. In the Emission Spectra tool, select each element to see its emission
spectrum.
2. In the data table below, record the element symbol, atomic number, the
lowest wavelength present in the spectrum (in nanometers), the highest
wavelength in the spectrum (in nanometers), and the total number of lines in
the spectrum.
3. Watch for any patterns in the spectra. For example, is there any correlation
between an element’s atomic number and the lowest or highest wavelength
in its spectrum? Do larger elements consistently have more spectral lines?
Collect Data
Record data about the different emission spectra below.
Emission Spectra of Several Elements
Element
Symbol
Atomic
Number
Lowest
Wavelength
in Spectrum
(nm)
Highest
Wavelength
in Spectrum
(nm)
Total
Number of
Spectral
Lines
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Analyze
Answer the questions.
4. Compare the spectrum of the unknown gas collected at the bulb company
with the data in your table. Which gas is leaking into the lab? Make a claim
and support your claim with evidence.
The leaking gas is: ___________________________________________
Evidence:
5. In the Emission Spectra tool, a table shows the ranges for wavelength,
frequency, and photon energy for different colors of light. What color of light
is associated with the highest energy? How does this relate to flame color on
a stove?
6. Using your data, compare atomic number with total number of spectral lines.
Is there a pattern? What might explain the presence or absence of a pattern
based on what you know about atoms, electrons, and emission spectra?
7. Using your data, compare atomic number with lowest and highest
wavelengths in spectrum. Is there a pattern? What might explain the
presence or absence of a pattern based on what you know about atoms,
electrons, and emission spectra?
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Part 2. Stellar Spectra
Background
Think about your signature. It can be used to identify you because it has unique
qualities that only your hand gives it, such as a peak in your printed S, or a long
tail in your cursive Y. Space objects also have signatures. The light coming from a
space object is unique to that object, and the spectra generated for space objects
record these unique characteristics in the spectrum’s shape, intensity, wavelength
range, and distinct lines.
In this part of the lab, you will analyze light spectra to determine the composition of
stars. The spectra in this part of the lab will be more complex than spectra for the
elements. This is because the light coming from a star includes light generated by
several different elements simultaneously.
Scientists have identified several patterns in the spectra of stars. The lines
present in the spectrum provide information about the composition of the star and
whether it formed early or late in the history of the universe. Use these general
principles to guide you as you interpret the stellar spectra presented in the lab.
• Stars that contain just hydrogen and helium formed early in the universe.
Stars with heavier elements, such as carbon or oxygen, formed later because
heavier elements had to form within earlier stars.
Investigate
Follow the following instructions to analyze different star composition.
In the following image, use the elemental spectra provided to analyze if its
signature lines are present in 3 unknown star's spectra.
Check each element for its presence in the spectrum.
Use checkmarks to record which elements are present in the star in the data
table on page 6.
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Hint: Be sure to use a straight edge to help you line up the spectral lines when trying to
determine the elements present within the mystery stars. Sometimes our eyes can play
tricks on us and stationary lines may appear to move or relocate.
5
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Collect Data
Unless directed otherwise, use check marks to record information about each stellar
spectrum.
Characteristics of Different Stellar Spectra
Star
Name
H? He? Na? Ca? Hg?
6
Analyze
Answer the questions to analyze the stellar spectra presented in the lab.
1. Based on your data, which star might have formed when the universe was
young? Which one might have formed more recently? Explain your
evidence and reasoning for each choice.
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Draw Conclusions
2. Write 1–2 paragraphs that summarize how spectroscopy provides
information about the composition of objects. Use data from the lab to
support claims you make, and provide compelling reasoning. Make an effort to
use proper writing conventions in your summary (such as good punctuation,
spelling, and capitalization).
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3. Look again at the Orion constellation. With
one exception, all the stars that make up
the constellation are bright, young blue
giant or supergiant stars. The exception is
Betelgeuse, one of the brightest stars in the
night sky. Betelgeuse is a red giant star
located at Orion’s left shoulder. Explain how
the stellar spectrum of Betelgeuse would be
different than the spectra of the other stars
in Orion. Include information what elements
might be represented in the spectral lines.
3 answers
Spectroscopy Tool Lab Report
Part 1: Emission Spectra
Collect Data
| Element Symbol | Atomic Number | Lowest Wavelength in Spectrum (nm) | Highest Wavelength in Spectrum (nm) | Total Number of Spectral Lines |
|----------------|----------------|------------------------------------|-------------------------------------|---------------------------------|
| H | 1 | 656 | 486 | 5 |
| He | 2 | 587 | 389 | 5 |
| Na | 11 | 590 | 589 | 2 |
| Ca | 20 | 396 | 393 | 3 |
| Hg | 80 | 313 | 254 | 6 |
| Ne | 10 | 640 | 585 | 5 |
Analyze
-
Claim and Evidence:
The leaking gas is: Neon (Ne).
Evidence: The spectrum of the unknown gas displayed prominent lines in the same range of wavelengths as those measured for neon, specifically around 640 nm.
-
The color of light associated with the highest energy is violet. This relates to flame color on a stove as a higher flame temperature (more energy) corresponds to blue or white flames, indicating higher energy states.
-
Pattern Analysis: There appears to be a slight pattern - as atomic number increases, the number of spectral lines tends to also increase. This can be explained by the complexity of electron interactions in larger atoms; they have more electrons and energy levels which can produce more transitions resulting in more spectral lines.
-
Wavelength Analysis: There does not appear to be a strong consistent pattern between atomic number and the wavelengths (lowest and highest) in their spectra. The differences in electron configuration and energy level transitions can cause significant variability in wavelength emission, decoupling the expected correlation.
Part 2: Stellar Spectra
Collect Data
| Star Name | H? | He? | Na? | Ca? | Hg? |
|-----------|----|-----|-----|-----|-----|
| Star 1 | ✅ | ✅ | ✅ | ❌ | ❌ |
| Star 2 | ✅ | ❌ | ✅ | ✅ | ❌ |
| Star 3 | ✅ | ✅ | ❌ | ✅ | ✅ |
Analyze
- Based on the data, Star 1 may have formed when the universe was young as it contains only hydrogen and helium. Star 2, containing heavier elements such as calcium, indicates it formed more recently as heavier elements required prior stellar generations to form and enrich the interstellar medium.
Draw Conclusions
-
Spectroscopy provides critical insights into the composition of celestial objects by analyzing the unique light emitted or absorbed. Each element has a distinct spectral signature, revealing its presence in a given light spectrum. For instance, in our lab, stars with hydrogen and helium alone were identified as older, reflecting their simpler elemental makeup from earlier times in the universe's history, while heavier elements in younger stars suggest further evolution through supernova events. This method allows scientists to decode the universe's narrative through the light it emits.
-
The stellar spectrum of Betelgeuse would differ significantly from other stars in the Orion constellation due to its classification as a red giant star. Betelgeuse’s spectrum is expected to show prominent lines representing heavier elements formed in previous generations of stars, such as carbon and oxygen. In contrast, the majority of stars in Orion, being blue giants, would predominantly exhibit lines from lighter elements such as hydrogen and helium. Betelgeuse’s unique spectral characteristics not only reflect its advanced stage in stellar evolution but also provide clues about the chemical processes that shaped the current stellar population within the Orion constellation.
This lab report outlines the analysis of emission spectra for various elements and the stellar spectra to infer the composition of gases and stars. By understanding these spectral characteristics, we gather essential clues about the physical and chemical processes occurring both in laboratories and in the cosmos.
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