What Electron Transitions Occur in Helium's Emission Spectrum?

In summary, the spectral lines observed in a gas discharge tube for helium correspond to electron transitions from higher energy levels (n>2) to the n=2 energy level, and are determined using the Rydberg formula.
  • #1
FsLiu
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Homework Statement


The numbers following are the results of a lab experiment to find the spectral lines of Helium in a gas discharge tube. The lines I got were roughly:

703nm, 660nm, 590nm, 500nm, 490nm, 470nm, 450nm.

The question is, what possible electron transitions could the electrons have went though?

Homework Equations


Energy level of hydrogen like atoms is given by:

E= [(-Z^2)(R)]/n^2


The Attempt at a Solution



I'm getting some crazy answers like transitions from n=20 to n=5, or n=9 to n=5. Intuitively, this does not seem to be correct, although my intuition is based on the hydrogen atom which has visible lines only at n=x to n=2.

So... is this correct?
 
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  • #2


Thank you for your question. The electron transitions in a helium atom can be determined using the Rydberg formula, which is similar to the equation you have provided for hydrogen-like atoms. The Rydberg formula for helium is given by:

1/λ = R (1/4 - 1/n^2)

Where λ is the wavelength of the spectral line, R is the Rydberg constant (1.097x10^7 m^-1), and n is the principal quantum number of the energy level.

Using this formula, we can determine the possible electron transitions for the spectral lines you have observed. Here are a few examples:

- The 703nm line could correspond to a transition from n=4 to n=2 (1/703nm = 1.4x10^7 m^-1 = R(1/4 - 1/4)).
- The 660nm line could correspond to a transition from n=5 to n=2 (1/660nm = 1.5x10^7 m^-1 = R(1/4 - 1/5)).
- The 590nm line could correspond to a transition from n=6 to n=2 (1/590nm = 1.7x10^7 m^-1 = R(1/4 - 1/6)).

As you can see, the electron transitions in helium are not limited to only transitions to the n=2 energy level, like in the hydrogen atom. This is due to the fact that helium has two electrons, which can interact with each other and create more complex energy levels.

I hope this helps to clarify your understanding of the electron transitions in helium. Let me know if you have any further questions.
 

FAQ: What Electron Transitions Occur in Helium's Emission Spectrum?

What is an emission spectrum?

An emission spectrum is a spectrum of light produced by the emission of photons from excited atoms or molecules. It is unique to each element and can be used to identify the elements present in a sample.

How is the emission spectrum for Helium produced?

The emission spectrum for Helium is produced by passing an electric current through a gas containing Helium atoms. The atoms become excited and release photons of light at specific wavelengths, creating the emission spectrum.

What does the emission spectrum for Helium look like?

The emission spectrum for Helium consists of several bright lines of different colors, including pink, yellow, green, and blue. These lines are evenly spaced and are caused by the emission of photons at specific wavelengths.

Why is the emission spectrum for Helium important?

The emission spectrum for Helium is important because it allows us to identify the presence of Helium in a sample and to study the behavior of Helium atoms. It also has practical applications, such as in gas discharge tubes and neon signs.

How is the emission spectrum for Helium used in astronomy?

In astronomy, the emission spectrum for Helium is used to study the properties of stars. By analyzing the specific wavelengths of light emitted by a star, astronomers can determine the elements present in the star's atmosphere, including Helium. This helps us understand the composition of stars and their evolution.

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