Question

Q1)

Calculate the energy of an electron in the n = 2 level of a hydrogen atom.

Energy = _______Joules

Q2)

What would be the wavelength of radiation emitted from a hydrogen atom when an electron moves from the n = 2 to n = 1energy level? In what region of the spectrum does this radiation lie?

Wavelength = ________nm

Region = _________(ultraviolet or visible or infrared)

Answer 1

1)
Energy in eV in nth level is given by:
En = -13.6/n^2
for n=2,
E = -13.6/2^2 eV
E = -13.6/4 eV
E = -3.4 eV
E = -3.4*1.602*10^-19 J
E = 5.45*10^-19 J

Answer: 5.45*10^-19 J

2)
Here photon will be emitted
1/lambda = R* (1/nf^2 - 1/ni^2)
R is Rydberg constant. R = 1.097*10^7

1/lambda = R* (1/nf^2 - 1/ni^2)
1/lambda = 1.097*10^7* (1/1^2 -   1/2^2)
lambda = 1.215*10^-7 m
lambda = 122 nm
Answer: 122 nm
this wavelength is less than wavelength of violet rays
So, this is ultraviolet