Emission Spectroscopy and Excited Elements

Mr. Bartelt’s Chemistry Class

I. IntroductionToday, you’ll get the chance to actually see the hydrogen emission lines that led Bohr to put forth his history solar system model of the atom. You will also observe the emission lines of several other gasses in the lab. Our experiment will begin by looking at the emission lines of the florescent lights in our lab and at the spectral line of various objects in the lab. From the data we collect, we will attempt to determine what gasses are being excited in the florescent bulbs that light our school. II. Objective: • TLW observe and record the characteristic emission spectra of various gasses. • TLW identify substances by their color emission.

Caution:We will be working with breakable glass tubes and high-voltage sources in lab today. This equipment is not to be handled by the students. Parts of today’s experiment will be conducted in the dark so be careful.

Materials Needed:

SpectroscopesHigh-voltage power sourceGasses (N2, H2, I2, Mg, He, Ne, Ar)

II. Procedure:1. Observe the emission spectrum an excited gas in your group. Record your observations of the gasses using the data sheet provide. Color code you spectral lines for clarity.

2. When you are finished recording a sample wait until you are instructed to move onto the next sample and record your data (right).

3. Once you have observed these various substances, take another look at the lights in the lab.

Questions to be addressed in the conclusion

1. Why are specific lines observed in when these gasses are observed through spectrophotometers instead of the entire rainbow as when sunlight is split through a prism?

2. How are electrons responsible for the appearance of these lines?