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University of Nebraska–Lincoln

Electromagnetic Spectral Activities

Spectral Analysis

Purpose

The purpose of this activity is to introduce students to the fact that chemical elements can be identified by their spectral signatures. This understanding will help them later when the concept of surface feature signatures is introduced.

Materials

  • lab hand-out on Spectral Analysis
  • spectroscopes
  • gas tubes (neon, oxygen, sodium, helium, hydrogen and argon)
  • colored pencils
  • spectral chart of the given elements

About this Activity

This activity involves a laboratory investigation for students to perform. In this investigation, students will observe various elements through a spectroscope. Using a spectral chart or text-book of the spectra of known elements, students will match their results to the given spectra to determine the unknown elements.

Procedure

  1. Pass out a spectroscope, lab hand-out, and spectral chart to each student.
  2. Review how to use a spectroscope.
  3. Show each of the gas tubes representing one of the six elements. Have students observe each element using a spectroscope. They should draw the pattern of what they saw onto their lab hand-out.
  4. The lab questions can be done individually or in their laboratory groups.

Name______________________________________ Date___________

Spectral Analysis

Directions:

Look at the patterns seen through the spectroscope. Using colored pencils, draw the patterns of the colors that you see in the space provided.

Conclusion:

  1. How did the spectra of the samples differ?
  2. If all the bands you observed were drawn on one band, describe what it would look like?
  3. How can scientists tell what elements are present in a given sample?
  4. Spectral lines are often called the "fingerprints" of the elements.Why do you think this is so?
  5. What other device besides a spectroscope breaks light into its component colors?