In physics, the Lyman series is the series of transitions and resulting emission lines of the hydrogen atom as an electron goes from n ≥ 2 to n = 1 (where n is the principal quantum number referring to the energy level of the electron). The transitions are named sequentially by Greek letters: from n = 2 to n = 1 is called Lyman-alpha, 3 to 1 is Lyman-beta, 4 to 1 is Lyman-gamma, etc. The series is named after its discoverer, Theodore Lyman. The first few hydrogen atom electron orbitals shown as cross-sections with color-coded probability density. ... A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range, compared with the nearby frequencies. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... Properties In chemistry and physics, an atom (Greek ἄτομος or átomos meaning indivisible) is the smallest particle of a chemical element that retains its chemical properties. ... The electron is a fundamental subatomic particle that carries an electric charge. ... In atomic physics, the principal quantum number symbolized as n is the first quantum number of an atomic orbital. ... The Lyman-alpha line is a spectral line of hydrogen in the Lyman series, emitted when the electron falls from the n=2 orbit to the n=1 orbit. ... Theodore Lyman (1874 - 1954) was a U.S. physicist and spectroscopist. ...

History

The first line in the ultraviolet spectrum of the Lyman series was discovered in 1906 by Harvard physicist Theodore Lyman, who was studying the ultraviolet spectrum of electrically excited hydrogen gas. The rest of the lines of the spectrum were discovered by Lyman from 1906-1914. Theodore Lyman (1874 - 1954) was a U.S. physicist and spectroscopist. ...

The spectrum of radiation emitted by hydrogen is non-continuous. Here is an illustration of the first series of hydrogen emission lines:

Historically, explaining the nature of the hydrogen spectrum was a considerable problem in physics. Nobody could predict the wavelengths of the hydrogen lines until 1885 when the Balmer formula gave an empirical formula for the visible hydrogen spectrum. Within five years Johannes Rydberg came up with an empirical formula that solved the problem, presented first in 1888 and in final form in 1890. Rydberg managed to find a formula to match the known Balmer series emission lines, and also predict those which were not yet discovered. Different versions of the Rydberg formula with different simple numbers were found to generate different series of lines. The first few hydrogen atom electron orbitals shown as cross-sections with color-coded probability density. ... The wavelength is the distance between repeating units of a wave pattern. ... Janne Rydberg Johannes Robert Rydberg, commonly known as Janne Rydberg, (November 8, 1854 - December 28, 1919), was a Swedish physicist mainly known for devising the Rydberg formula, in 1888, which is used to predict the wavelengths of photons (of light and other electromagnetic radiation) emitted by changes in the energy... In chemistry, the empirical formula of a chemical is a simple expression of the relative number of each type of atom (called a chemical element) in it. ... Two of the balmer lines (α and β) are clearly visible in this emission spectrum of a deuterium lamp. ...

The Lyman series

The version of the Rydberg formula which generated the Lyman series was: The Rydberg formula (Rydberg-Ritz formula) is used in atomic physics for determining the full spectrum of light emission from hydrogen, later extended to be useful with any element by use of the Rydberg-Ritz combination principle. ...

Where n is a natural number greater or equal than 2 (i.e. n = 2,3,4,...).

Therefore, the lines seen in the image are the wavelengths corresponding to n=2 on the left, to n= on the right (there are infinitely many spectral lines, but they become very dense as they approach to n=, so only some of the first lines and the last one appear).

The wavelengths (nm) in the Lyman series are all ultraviolet:

2-1 -- 121.6

3-1 -- 102.5

4-1 --- 97.2

5-1 --- 94.9

6-1 --- 93.7

7-1 --- 93.0

8-1 --- 92.6

9-1 --- 92.3

10-1 -- 92.1

11-1 -- 91.9

Limit: 91.15 nm

Explanation and derivation

In 1913, when Niels Bohr produced his Bohr model theory, the reason why hydrogen spectral lines fit Rydberg's formula was explained. Bohr found that the electron bound to the hydrogen atom must have quantized energy levels described by the following formula: Niels (Henrik David) Bohr (October 7, 1885 – November 18, 1962) was a Danish physicist who made fundamental contributions to understanding atomic structure and quantum mechanics. ... The Bohr model of the hydrogen atom. ...

According to Bohr's third assumption, whenever an electron falls from an initial energy level(E_i) to a final energy level(E_f), the atom must emit radiation with a wavelength of:

There is also a more comfortable notation when dealing with energy in units of electronvolts and wavelengths in units of angstroms: The electronvolt (symbol eV, or, rarely and incorrectly, ev) is a unit of energy. ... An angstrom, angström, or ångström (symbol Å) is a unit of length. ...

Replacing the energy in the above formula with the expression for the energy in the hydrogen atom where the initial energy corresponds to energy level n and the final energy corresponds to energy level m:

where R is the same constant Rydberg found.

For the connection between Bohr, Rydberg, and Lyman, one must replace m by 1 to obtain:

which is Rydberg's formula for the Lyman series. Therefore, each wavelength of the emission lines corresponds to an electron dropping from a certain energy level (greater than 1) to the first energy level.

See also

• Bohr model
• H-alpha
• Hydrogen spectral series
• Rydberg formula
• Balmer series
• Paschen series

The Bohr model of the hydrogen atom. ... In physics and astronomy, H-alpha, also written Hα, is a particular emission line created by hydrogen. ... This article needs to be cleaned up to conform to a higher standard of quality. ... The Rydberg formula (Rydberg-Ritz formula) is used in atomic physics for determining the full spectrum of light emission from hydrogen, later extended to be useful with any element by use of the Rydberg-Ritz combination principle. ... Two of the balmer lines (α and β) are clearly visible in this emission spectrum of a deuterium lamp. ... The Paschen series is the series of transitions and resulting emission lines of the hydrogen atom as an electron goes from n ≥ 4 to n = 3 (where n refers to the energy level of the electron). ...

External links

• Lyman series (animation)
• Lyman discovers series