Explore different types of emission spectra and compare known spectra of elements to identify an object of unknown composition. Analyze light from distant objects using spectral analysis (spectroscopy) to determine many of their physical parameters.

Explore different types of emission spectra and compare known spectra of elements to identify an object of unknown composition. Analyze light from distant objects using spectral analysis (spectroscopy) to determine many of their physical parameters.

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? Which element has the least complexity? Note, however, that number of visible emission lines does not necessarily indicate atomic complexity. 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.

Turn to page 591 of the 7^th edition (page 595 for the 6^th edition) of your Cosmic Perspective Note the bright reddish color of the emission nebula above the famous dark Horsehead Nebula.  This is a hot thin gas primarily made of hydrogen.  What is the predominant wavelength of the photons emitted by the gas in this nebula?  (Hint:  Look at Figure 5.15 on page 152 in the 7^th edition, or page 158 in the 6^th edition of the book.)
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? (Some of you may be old enough to remember the original neon signs!)