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Demonstration Lab: Line Spectra

Purpose:
It is the purpose of this activity to observe the line spectra of some elements and to identify several elements by their line spectra.

Materials:* gas discharge tubes
* natural sunlight
* diffraction grating or spectroscope
* power source

Procedure:
1. Look out the window through the diffraction grating or spectroscope.Draw and label the spectrum you observe using Table 1(reverse).
2. Upon direction from your teacher, look through your diffraction grating or spectroscope and observe the spectra produced by eachof the gas discharge tubes.
3. In each case for step #2, record the name of the gas in the discharge tube, sketch the spectrum, and indicate the color of each observed using Table 1(reverse).4. Use the diffraction grating or spectroscope to look at a ceiling light in your classroom.
5. For step #4, sketch the spectrum and indicate the color of each observed line when viewing theceiling light.
6. Identify the mystery gas contained within the ceiling light using the information you obtain in Step #5.

Background:
1. Define each of the following terms in your own words:a. Spectroscopy: it is the study involving the relationship between matter and its radiated energy.
b. Spectral line: dark or bright lines that separate colors in what would be acontinuous spectrum.
c. Photon: small particles in a stream of light emitted in an atomic spectrum.
d. Quantum and quanta: the package of energy in photons.

2. Explain what happens toan electron in the following scenarios:
e. Energy is absorbed: The electron is moving up energy levels.
f. Energy is emitted: The electron is moving down energy levels.

Observations:Table 1: Line Spectra for Selected Elements and Light Sources |
Substance | Line Spectra/ Spectrum | Real Line Spectrum |
Natural Sunlight | R,O,Y,G,B,I,V | |
Hydrogen | Purple, Light...