**Energy levels of Hydrogen Atom:
The Balmer Series**

**Obj: **Determine photon energy and quantum number of
electrons returning to n = 2 in the hydrogen atom.

**Materials: **H_{2 }gas tube, spectrometer

**Methods & Analysis**

(*Note: run the spectrum tube for no more than 30 seconds with
a 30 seconds cooling period*.)

1. Looking through the diffraction grating at the
ionized hydrogen gas, estimate the λ of the red, blue, and
violet bright lines to the nearest 10 nm using the spectrum
chart. [1 nm = 1 x 10^{-9} m] There should be a minimum
of three lines visible.

2. Calculate for each color the energy E (hc/λ)
of that photon in Joules and eV.

3. Compare your energy calculations with the
energy *differences* shown on your reference table.
Account for any discrepancies.
What do these energy differences indicate?

4. For each visible photon, determine the quantum
number n from which it returned to n = 2 of hydrogen.
Use your reference table for assistance.

5. Which color has the highest frequency?;
energy?; the
shortest λ ?; most and least momentum?

6. Repeat steps 1-5 for mercury gas, choosing two
colors.

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