Video Transcript
Which of the following diagrams
best represents the Paschen series of transitions?
We’re being asked about electron
energy level transitions and specifically to choose which of the four diagrams shows
the Paschen series of transitions. Before we can choose the right
diagram, we should remind ourselves about how electron transition series are
named.
First of all, only transitions
where an electron loses energy, or goes from a higher energy level to a lower one,
belong to named series such as the Paschen series. Transitions where electrons gain
energy and go up to higher energy levels are not included in these named series. This allows us to eliminate answer
options (B) and (C).
Importantly, it’s the energy level
that the electron transitions down to that determines which series the transition is
a part of. It does not matter which energy
level the electron started from. Electron transitions down to level
1 are part of the Lyman series. Transitions down to level 2 are
part of the Balmer series. And transitions down to level 3 are
known as the Paschen series.
When we look at the remaining
answer options, we see that option (D) shows transitions to the second energy level,
which is the Balmer series. Option (A) shows transitions down
to the third energy level, which is the Paschen series we are looking for. Our final answer is option (A).
