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2.05
Electron
Arrangement and
EMR – Virtual Lab
Line Spectra
Part I: Flame Tests
• How do atoms produce light?
– When energy is added to an atom, the
electrons will absorb the energy and move to
higher energy levels.
– The electrons are now in the “excited state”
• Unstable, temporary situation
– Consequently electrons will ‘fall’ back down to
a lower energy level, dispersing the added
energy in the form of Electromagnetic
Radiation (light)
– The difference of energy will determine which
color of light is emitted
• We can use the color of light to determine
the locations of the electron orbitals.
• The differences in orbital location and
potential energy are unique to every
element.
• We can use the color produced to identify
the element.
Flame Test Results
Identification of the Unknown Solutions
Element
Flame Color
Barium
Calcium
Potassium
Rubidium
Sodium
Lithium
Unknown #1
Unknown #2
Lab Report: Fill in data table with the flame colors (5 points)
Identify each unknown from part 1 of the lab, and briefly explain
why you identified each unknown as you did. (2 points)
Part II - Spectroscopy
• Spectroscopy is the analysis of line spectra
and of the way light interacts with matter
• Light passes through a narrow slit to
produce a beam of light. It is then
separated using a prism. Different colors of
visible light appear as different lines
according to their wavelengths.
• Different elements produce different line
spectra. There is unique spacing between
the energy levels
How spectroscopy works
Hydrogen Line Spectra
Lab report: Record the color and wavelength
(nm) for each line in your data table. (5 points
for entire data table)
Helium Line Spectra
Lab report: Record the color and wavelength
(nm) for each line in your data table.
Sodium Line Spectra
Lab report: Record the color and wavelength
(nm) for each line in your data table.
Neon Line Spectra
Lab report: Record the color and wavelength
(nm) for each line in your data table.
Mercury Line Spectra
Lab report: Record the color and wavelength
(nm) for each line in your data table.
Compare Spectrums
Lab Report: Describe the line spectrum of the
star. Give the color and wavelength value of the
five brightest lines in the spectrum. (3 points)
Conclusion
1. Explain, in your own words, why different elements produce different
colors of light when heated. (5 points)
2. Why do you think that the elements had to be heated before they
emit the colored light? (2 points)
3. What element do you think is the most abundant in the star that you
observed in part 2? Explain your answer. (3 points)