1A.11

[Annie Ye]

In the spectrum of atomic hydrogen, several lines are gen- erally classified together as belonging to a series (for example, Balmer series or Lyman series, as shown in Fig. 1A.10). What is common to the lines within a series that makes grouping them together logical?

[Nuoya Jiang]

For this question, try to think of the the lower energy level of these groups of lines. For example, for the Lyman series, these lines show the lower energy level of the transition of an electron from different energy levels is n=1, while for Balmer, it is n=2.

[VLi_2B]

Can someone also explain why for the Lyman series the lowest energy level is n=1; for the Balmer series the lowest n=2; for the Paschen series it's n=3; and for the Brackett series n=4?

[Camellia Liu 1J]

I'm pretty sure that its a result of experimental discovery. Electrons change energy levels in quantized values, and when it transitions between different levels, it emits or absorbs energy equal to the energy difference between the original state and the now-different state. The different series that have been discovered and named are certain sequences of lines that correspond to these certain atomic transitions that all begin or end with the same atomic state in hydrogen.

The Lyman series, for example, involves the electron transitions that either start or end with the ground state of hydrogen. The Balmer series involves transitions dealing with absorptions or emissions from the first excited state of hydrogen, which happens to be n=2.