Question

I was having trouble with some lab question on atomic emission spectra.

Also answer the following questions about your observations: Are the lines present in the hydrogen spectrum the same lines predicted by the Bohr model the atom? Which lines, if any, are missing? Why might there be lines missing? Compare the spectral lines from your unknown substance to the other spectra you observed. Based on these comparisons, what is the identity of the unknown substance? Are there any general trends in the emission spectra you observed? That is, do there appear t(be any periodic trends in the number or color of observed lines? Optional challenge question: Should the Bohr model predict the correct emission lines for the He ast ion ? Why or why not? Use the Bohr model to predict some of the visible emission lines of the He ast ion. Then calculate the wavelengths in nm corresponding to the transitions n=4 rightarrow 3, and n=6 rightarrow 4. Can either of these be observed in your He emission spectrum?

Answer 1

1)  It turns out that the energies of all the other transitions don't lie within range of energies included in the visible spectrum. As a result, even though these transitions occur, your eyes can't see the light that's given off as a result. Clearly, then, the predictions from Bohr's model give a perfect fit when compared to the hydrogen atomic spectrum. So, wesome lines are not misssing. But we can't see them.

3)

No general trend observed. Wavelegth correspondong to energy lost when electron jumps from higher energy orbit to lower energy orbit is calculated. Colour of visible light corresponding that wavelength appears in atomic spectra of a particular atom.

4) Bohr's model is applicable only for single electron atom. Here, He+ is a single electron atom. So, Bohr's model should predict the correct emission line for He+ ions