Name: Period: Date:

 

Observing Bright Line Spectra

 

Overview of the Lab:

In this lab you will be looking at the specific wavelengths emitted by atoms of different elements as their electrons move from the excited state back to the ground state. The energy added (in the form of electricity) to move the electron out to the excited state is equal to the energy of the photon of light emitted as the electron falls back to the ground state. Spectroscopes will be used to separate the different wavelengths of light so that the specific spectral lines can be observed rather than just observing the overall color (as we did in the flame tests).

 

Materials:


Gas Tubes, Light Spectroscopes, Colored, Pencils (or Markers)


 

Procedure:

1.        Look through the spectroscope at the fluorescent lights above. Draw what you see in the appropriate box in the data section of this lab.

2.       Look through the spectroscope at the incandescent light. Draw what you see in the appropriate box in the data section of this lab.

3.       Look through the spectroscope at the different gas tubes. Draw what you see for each in the boxes and label the boxes.

4.       Return the spectroscope to the bag and then return all of your pencils or markers.

 

Data:

Light Source:

 

 

 

 

 

violet

 

 

blue

 

teal

 

 

 

green

 

 

yellow

orange

red

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0.40

0.50

0.60

0.70

ultraviolet

Wavelength in micrometers (10-6m)

infrared

 

 

Light Source:

 

 

 

 

 

violet

 

 

blue

 

teal

 

 

 

green

 

 

yellow

orange

red

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0.40

0.50

0.60

0.70

ultraviolet

Wavelength in micrometers (10-6m)

infrared

 

Light Source:

 

 

 

 

 

violet

 

 

blue

 

teal

 

 

 

green

 

 

yellow

orange

red

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0.40

0.50

0.60

0.70

ultraviolet

Wavelength in micrometers (10-6m)

infrared

 

 

Light Source:

 

 

 

 

 

violet

 

 

blue

 

teal

 

 

 

green

 

 

yellow

orange

red

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0.40

0.50

0.60

0.70

ultraviolet

Wavelength in micrometers (10-6m)

infrared

Conclusion Questions:

 

1. How is spectrometry used to determine the composition of stars?

2. What is the difference between what occurred in the flame test lab and what occurred in this lab? What is the similarity?

3. Explain what causes the spectral lines.

4. Explain why all elements have a characteristic set of spectral lines.