Part 1: Continuous, Emission Line, and Absorption line Spectra

Go to the website http://jersey.uoregon.edu/vlab/elements/Elements.html (be patient, it may take a few moments to open or see the end of this paragraph).  This is an almost complete periodic table of the elements.  You can choose to view the spectrum of each element either as an emission spectrum or an absorption spectrum.  Study the spectra of several of the elements, choosing both simpler and more complex atoms, looking at both absorption and emission spectra.  Note: at times the uoregon.edu site has trouble with high traffic.  If the site doesn't work for you after multiple attempts to access it please use this site which has  the atomic emission spectrum for elements in the periodic table

http://chemistry.bd.psu.edu/jircitano/periodic4.html along with this site:

http://amateurspectroscopy.com/color-spectra-of-chemical-elements.htm. To learn more about absorption line spectra please visit this site

http://bcs.whfreeman.com/universe7e/content/ch05/0503001.html. (Video of whfreeman animation http://screencast.com/t/r1CXkGfR)

Next, look at the emission line spectra for the following elements:

Hydrogen (H), Helium (He), Oxygen (O), Neon (Ne), Argon (Ar)

(atomic numbers 1, 2, 8, 10, and 18)

1. Judging from the number of visible energy-level transitions (lines) in the spectra, which of the above elements would you conclude has the most complex atomic structure?

2. Which element has the least complexity?

3. For a given atom, will the spectral lines be at different wavelengths depending on whether you are viewing an emission spectrum or an absorption spectrum?  Explain why or why not. (Hint:  click between absorption and emission, do the emission lines and the absorption lines appear in the same place.  You can also take a look at this website: http://csep10.phys.utk.edu/astr162/lect/light/absorption.html) alternate site: http://astronomy.nmsu.edu/geas/lectures/lecture19/slide02.html

The wavelengths will be the same whether it is an emission or an absorption spectrum. What will change is whether you see bright lines of color or black bands at those wavelengths.

4. Now that you have seen the emission spectrum for neon, what color do you suppose a tube of excited neon gas would give off if you were to look at it without a prism or diffraction grating? At what color are the majority of the spectral lines located at?

Part 2:  Identifying an Unknown Gas

In the figure below is a set of made-up spectra from some made-up elements (Denverium, Boulderium, Brightonium,  etc.).  Use these element names when determining what elements are present in the observed spectrum (bottom spectrum) of the Colorado Nebula.

 5. What elements are present in the object that produced the "Spectra of the Colorado Nebula" (the lowest spectra set below the other elements)?

6. Which elements are NOT present in the "Spectra of the Colorado Nebula"?

7. Explain the method you used to answer the last question and relate this activity to the way astronomers use spectra to identify the composition of a star.

Part 3:  Summarizing What We Learned

Finally, watch this video, https://www.youtube.com/watch?v=n_KyYFYNvpI.  Write a short summary of what you learned in this lab and how we can take advantage of spectroscopy to find out the make-up of objects in our universe. (Summary needs to be a minimum of 100 words long.)