Spectral Series

A spectral series is a collection of wavelengths arranged in a logical order. Light, or any electromagnetic radiation released by energised atoms, has this property.

Because the hydrogen atom is the most basic atomic system found in nature, it produces the most basic series. When a slit allows a beam of light or other radiation to enter the device, each component of the light or radiation forms an image of the source. When resolved under the spectroscope, these images can be seen. 

The photos will be in the shape of parallel lines with consistent spacing positioned next to each other. When moving from a higher to a lower wavelength side, the lines will be farther apart on the higher wavelength side and eventually closed. The shortest wavelength has the fewest separated spectral lines, which is referred to as the series limit.

Line spectrum of the hydrogen atom

A hydrogen atom is made up of several line spectrum series, including:

1. Pfund Series
2. Brackett Series
3. Paschen Series
4. Balmer Series
5. Lyman Series

Spectral Series Formation

Bohr’s atomic model models and well explains the set of energy levels/states that each atom encloses. Quantum numbers (n=1, 2, 3, 4, 5, 6,…..) are used to name energy states. A photon of energy n_h – n_l is released when electrons jump from higher energy states (n_h) to lower energy ones (n_l). Because the energy related to each state is fixed, the difference between them is also fixed, resulting in a transition between similar energy states producing the same energy photon.

The electron transition to a lower energy state divides the spectral series into equivalent series. Within the series, the Greek alphabets are utilised to separate the spectral lines of corresponding energy. Hydrogen has the following spectral series:

• Lyman series (n_l=1) The series was discovered by Theodore Lyman between 1906 and 1914. As a result, it bears his name. When electrons transition from higher energy states (n_h=2, 3, 4, 5, 6,…) to n_l=1 energy states, according to Bohr’s model, the Lyman series appears. The Lyman series’ wavelengths are all in the Ultraviolet band. For a list of wavelengths related to spectral lines, see the table below:

• Balmer series (n_l=2) Johann Balmer was the first to discover the series in 1885. As a result, the series is named after him. The Balmer series emerges when electrons go from higher energy levels (n_h=3,4,5,6,7,…) to a lower energy state (n_l=2). The wavelengths of the Balmer series are all visible in the electromagnetic spectrum (400 nm to 740 nm). The H-Alpha line of the Balmer series, which is also a part of the solar spectrum, is used in astronomy to identify hydrogen. See the table below for a list of wavelengths associated with spectral lines.

• Paschen series (n_l=3) In 1908, a German physicist named Friedrich Paschen was the first to notice the series. As a result, the series is named after him. The Paschen series develops when electrons migrate from higher energy levels (n_h=4, 5, 6, 7, 8, …) to lower energy states (n_l=3). All of the wavelengths in the Paschen series are in the infrared portion of the electromagnetic spectrum. The Brackett series, which has the smallest wavelength, overlaps with the Paschen series. This series overlaps with all subsequent ones. See the table below for a list of wavelengths associated with spectral lines.

• Brackett series (n_l=4) In the year 1922, an American physicist named Friedrich Sumner Brackett spotted the series for the first time. As a result, the series is named after him. The Brackett series develops when electrons move from higher energy levels (n_h=5, 6, 7, 8, 9 …) to lower energy states (n_l=4). The wavelengths of the Brackett series are all in the infrared region of the electromagnetic spectrum. See the table below for a list of wavelengths associated with spectral lines.

• Pfund series (n_l=5) In 1924, August Harman Pfund became aware of the series for the first time. As a result, the series is named after him. The Pfund series emerges when an electron transitions from a higher energy state (n_h=6, 7, 8, 9,10, …) to a lower energy level (n_l=5). The wavelengths of the Pfund series are all in the infrared region of the electromagnetic spectrum. See the table below for a list of wavelengths associated with spectral lines.

• Humphreys series (n_l=6) In 1953, an American physicist called Curtis J Humphreys spotted the series for the first time, and the series is named after him. The Humphreys series develops when electrons migrate from higher energy levels (n_h=7, 8, 9, 10, 11…) to a lower energy state (n_l=6). The wavelengths of the Humphreys series are all in the infrared region of the electromagnetic spectrum. For a list of wavelengths linked with spectral lines, see the table below.

Also, Check

• Bohr’s Model of Atom
• Electromagnetic Spectrum
• Difference between Absorption and Emission Spectra

Atomic Spectra is the spectrum of radiation of electromagnetic waves produced due to the transition of an electron from one energy level to another level within an atom. Atoms have an equal number of negative and positive charges. Atoms were described as spherical clouds of positive charges with embedded electrons in Thomson’s concept. In Rutherford’s model, one tiny nucleus carries the majority of the atom’s mass, as well as its positive charges, and the electrons orbit it.

Every element’s atoms have their own unique spectra and are stable. The spectrum is made up of line spectrums, which are parallel lines that are isolated. In this article, we will learn atomic spectra, its definition, and more in detail.