Question

In the below figure, ${E_1}$ to ${E_6}$ represent some of the energy levels of an electron in the hydrogen atom.
Which one of the following transitions produces a photon of wavelength in the ultraviolet region of the electromagnetic spectrum?

A) ${{\text{E}}_2} - {{\text{E}}_1}$
B) ${{\text{E}}_3} - {{\text{E}}_2}$
C) ${{\text{E}}_4} - {{\text{E}}_3}$
D) ${{\text{E}}_6} - {{\text{E}}_4}$

Answer 1

An electron in the lowest energy level of hydrogen atom $\left( {n = 1} \right)$ therefore it has energy of about 13.6 eV less energy than a motionless electron which is infinitely far from the nucleus.
The next energy level $\left( {n = 2} \right)$ where the energy is $\;3.4{\text{ }}eV$
For third $\left( {n = 3} \right)$ is $- 1.51{\text{ }}eV$,
For fourth energy level $\left( {n = 4} \right)$ is $- 0.85{\text{ }}eV$,
For fifth level of energy $\left( {n = 5} \right)$ is $\; - 0.54{\text{ }}eV$,and
For the sixth level of energy $\left( {n = 6} \right)$ is $- 0.38{\text{ }}eV$.

Complete step by step solution:
Lyman series: This series of lines has the lines that are emitted when an electron makes a transition from an outer orbit of quantum number to the First orbit of quantum number.
Therefore, Lyman discovered the spectral lines and the series are named after him.
The wavelengths of all the lines in the Lyman series of Hydrogen atoms belong to the ultraviolet band.

Hence the correct option is (A).

Note:
Balmer series: It includes the lines that are emitted when the electron from an outer orbit makes a transition to the orbit. This series is named after Johann Balmer. He gave an equation to predict the Balmer series in the year 1885, which is known as Balmer formula.
Paschen series: It includes the lines that are emitted by the transitions from an outer orbit to the orbit. Physicist Friedrich Paschen, first observed this kind of spectral series in the year 1908. The Paschen lines belong to the infrared band.
Brackett series: It includes the lines that are emitted by the transitions from an outer orbit. Frederick Sumner Brackett, a physicist who was the first man to observe the spectral lines in the year 1922.The spectral lines that belong to Brackett series range in the far infrared band.
Pfund series: It includes the lines that are emitted by the transitions from an outer orbit. This series was named after physicist August Herman Pfund, who experimentally discovered this series in the year 1924.