Spectrum of hydrogen atom

Before we can analyze the spectrum of hydrogen atoms, we must become more familiar with light. In Chapter 14 light was characterized by frequency or wavelength. (Reread Section 14-3.1.) Now we shall consider another property of light... 

Eventually, other series of lines were found in other regions of the electromagnetic spectrum. The Lyman series was observed in the ultraviolet region, whereas the Paschen, Brackett, and Pfund series were observed in the infrared region of the spectrum. All of these lines were observed as they were emitted from excited atoms, so together they constitute the emission spectrum or line spectrum of hydrogen atoms. 

Fig. 5 (a) Power spectrum of oxygen atoms of bound and free water molecules, (b) Power spectrum of hydrogen atoms of different kinds of water molecules. 

Figure 29.4 (a) Energy level of hydrogen atom in a magnetic field, (b) EPR spectrum of hydrogen atom. 

In 1913 Niels Bohr proposed his atomic theory with the help of the line spectrum of hydrogen atoms and Planck s quantum theory. His postulates can be summarized as follows ... 

Breit was the first to suggest [3] that the unanticipated results of hyperfine measurements [4,5] may be explained if the electron g value deviates slightly from 2, the Dirac value. This observation was soon confirmed by the experiment of Kusch and Foley [6]. Together with the discovery of the Lamb shift in the spectrum of hydrogen atom, this provided a timely stimulus for the renormalization... 

The colored Images are called spectral lines, p) The line emissbn spectrum of hydrogen atoms. 

Figure 1.12 The line emission spectrum of hydrogen atoms in the visible region.

Each canponent color is focused at a definite position, according to its wavelength, and forms a colored image of the slit on the photographic plate. The colored irtuxges are called spectral lines, (b) The line emission spectrum of hydrogen atoms. 

C To account for the emission or line spectrum of hydrogen atoms,... 

Each spectral line corresponds to photons possessing a definite energy. For example, the 4102-A line in the spectrum of hydrogen atoms corresponds to 4.842 X 10 erg/atom. 

Draw an energy-level diagram that represents all the possible lines in the emission spectrum of hydrogen atoms produced by electron transitions, in one or more steps, from n = 5 to = 1. 

The hydrogen atom and its spectrum are of enormous importance in astrophysics because of the large abundance of hydrogen atoms both in stars, including the sun, and in the interstellar medium. 

The hydrogen atom, containing a single electron, has played a major role in the development of models of electronic structure. In 1913 Niels Bohr (1885-1962), a Danish physicist, offered a theoretical explanation of the atomic spectrum of hydrogen. His model was based largely on classical mechanics. In 1922 this model earned him the Nobel Prize in physics. By that time, Bohr had become director of the Institute of Theoretical Physics at Copenhagen. There he helped develop the new discipline of quantum mechanics, used by other scientists to construct a more sophisticated model for the hydrogen atom. 

The Brackett series lines in the atomic spectrum of hydrogen result from transitions from n > 4 to n = 4. 

Wavelength (A) A characteristic property of a wave related to its color and equal to the length of a full wave, 133 atomic spectrum of hydrogen, 136 color and, 17t... 

Mathematical models are the link between what is observed experimentally and what is thought to occur at the molecular level. In physical sciences, such as chemistry, there is a direct correspondence between the experimental observation and the molecular world (i.e., a nuclear magnetic resonance spectrum directly reflects the interaction of hydrogen atoms on a molecule). In pharmacology the observations are much more indirect, leaving a much wider gap between the physical chemistry involved in drug-receptor interaction and what the cell does in response to those interactions (through the cellular veil ). Hence, models become uniquely important. 

The mass spectrum of 2-methylbenzaldehyde suggests an aromatic compound because of the intensity of the molecular ion and peaks at m/z 39, 51, and 65 (see Figure 6.2). The loss of hydrogen atoms and loss of 29 Daltons from the molecular ion indicate that this is an aromatic aldehyde. Looking up m/z 91 in Part III suggests the following structure ... 

Schematic representation of an apparatus that measures the emission spectrum of a gaseous element. Emission lines appear bright against a dark background. The spectmm shown is the emission spectrum for hydrogen atoms.

The Bohr atom went a long way toward explaining the nature of atoms, but there were problems. Although scientists could calculate the emission spectrum of hydrogen using the Bohr model, the model could not account for the spectra of heavier atoms. The biggest problem with the Bohr atom, however, lay in its lack of a... 

The discovery of two other series of emission lines of hydrogen came later. They are named for their discoverers the Lyman series in the ultraviolet range and Paschen series in the infrared region. Although formulas were devised to calculate the spectral lines, the physics behind the math was not understood until Niels Bohr proposed his quantized atom. Suddenly, the emission spectrum of hydrogen made sense. Each line represented the energy released when an excited electron went from a higher quantum state to a lower one. 

However, the comparison of the whole series of experimental facts involving IR-spectroscopy of adsorption of molecular and atomic hydrogen as well as the change in electric conductivity of adsorbent is indicative of a more complex phenomenon. For instance, in paper [97] both the spectra of adsorption of adsorbed molecular hydrogen were studied together with those of hydrogen atoms adsorbed from gaseous phase. In case when H2 are adsorbed in a dissociative manner one would have expected a manifestation of the same bands 3498 and 1708 cm or at least one of them inherent to adsorption of H-atoms in the spectrum of ZnO. 

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