Class 12 > Unit # 26: Atomic Physics > Spectral Series of Hydrogen Atom

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Spectrum of Hydrogen Atom

Video Lecture: Spectrum of Hydrogen Atom

Watch the complete lecture detailing the formation of the hydrogen atomic spectrum and its spectral series:

Watch directly on YouTube (https://youtu.be/4wbxIIblZOc)

Spectrum of Hydrogen Atom

When an electron jumps from a higher orbit to a lower orbit, it radiates energy which appears in the form of a spectral line. A set of such spectral lines is known as the hydrogen spectrum. The hydrogen spectrum is the simplest one, consisting of five major series:

1. Lyman Series: When an electron jumps from a higher orbit to the 1st orbit (ground state, $p = 1$), the radiation emitted forms the Lyman series. It is obtained in the ultraviolet region. The wave number can be calculated by:
   $\frac{1}{\lambda} = R_H \left( \frac{1}{1^2} - \frac{1}{n^2} \right)$     (where $n = 2, 3, 4, \dots$)
2. Balmer Series: When an electron jumps from a higher orbit to the 2nd orbit ($p = 2$), the radiation emitted forms the Balmer series. It is obtained in the visible region. The wave number can be calculated by:
   $\frac{1}{\lambda} = R_H \left( \frac{1}{2^2} - \frac{1}{n^2} \right)$     (where $n = 3, 4, 5, \dots$)
3. Paschen Series: When an electron jumps from a higher orbit to the 3rd orbit ($p = 3$), the radiation emitted forms the Paschen series. It is obtained in the infrared region. The wave number can be calculated by:
   $\frac{1}{\lambda} = R_H \left( \frac{1}{3^2} - \frac{1}{n^2} \right)$     (where $n = 4, 5, 6, \dots$)
4. Brackett Series: When an electron jumps from a higher orbit to the 4th orbit ($p = 4$), the radiation emitted forms the Brackett series. It is obtained in the far infrared region. The wave number can be calculated by:
   $\frac{1}{\lambda} = R_H \left( \frac{1}{4^2} - \frac{1}{n^2} \right)$     (where $n = 5, 6, 7, \dots$)
5. Pfund Series: When an electron jumps from a higher orbit to the 5th orbit ($p = 5$), the radiation emitted forms the Pfund series. It is obtained in the far infrared region. The wave number can be calculated by:
   $\frac{1}{\lambda} = R_H \left( \frac{1}{5^2} - \frac{1}{n^2} \right)$     (where $n = 6, 7, \dots$)

Fig: Spectral series of hydrogen atom corresponding to electron transitions to different lower orbits.

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