Question

The energy levels of one-electron ions are given by the equation:

En=(-2.18*10^(-18)J)(Z^2/n^2)

The series in the He spectrum that corresponds to the set of transitions where the electron falls from a higher level to the nf = 4 state is called the Pickering series, an important series in solar astronomy. Calculate the Pickering series wavelength associated with the excited state ni = 9.

What region of the electromagnetic spectrum does this transition fall in?

radio
microwave
gamma
infrared
UV
visible
X ray

Answer 1

So calculate E for n = 9 (and Z is 2). Call that E1
Then calculate E for n = 4 (and Z is 2). Call that E2.
Subtract the two (disregard the sign), then delta E = hc/wavelength. All of that gives you one line. That's the n = 0 to n = 4 transition.
You will have other lines; for example:
n = 8 to n = 4
n = 7 to n = 4
n = 6 to n = 4
n = 5 to n = 4

Answer 2

Im suppose to solve for lambda. How do I do that?

Answer 3

After you have delta E, then
dE = hc/wavelength.

Answer 4

gdhs