Electrons Bohr model

The Bohr model is a determinant model of an atom. It implies that the position of the electron is exactly known at any time in the future, once that position is known at the present. The distance of the electron from the nucleus also is exactly known, as is its energy. And finally, the velocity of the electron in its orbit is exactly known. All of these exactly known quantities—position, distance from nucleus, energy, and velocity—can t, according to the Heisenberg uncertainty principle, be known with great precision simultaneously. 

Appendix 1 also shows how the periodic table of the elements (Appendix 5) can be built up from the known rules for filling up the various electron energy levels. The Bohr model shows that electrons can only occupy orbitals whose energy is fixed (quantized), and that each atom is characterized by a particular set of energy levels. These energy levels differ in detail between atoms of... 

However, in the sodium atom, An = 0 is also allowed. Thus the 3s —> 3p transition is allowed, although the 3s —> 4s is forbidden, since in this case A/ = 0 and is forbidden. Taken together, the Bohr model of quantized electron orbitals, the selection rules, and the relationship between wavelength and energy derived from particle-wave duality are sufficient to explain the major features of the emission spectra of all elements. For the heavier elements in the periodic table, the absorption and emission spectra can be extremely complicated - manganese and iron, for example, have about 4600 lines in the visible and UV region of the spectrum. 

In this chapter, you learned about the electronic structure of the atom in terms of the older Bohr model and the newer quantum mechanical model. You learned about the wave properties of matter, and how to describe each individual electron in terms of its four quantum numbers. You then learned how to write the electron configuration of an atom and some exceptions to the general rules. 

With the failure of the Bohr model it was found that the properties of an electron in an atom had to be described in wave-mechanical terms (p. 54). Each Bohr model energy level corresponding to... 

How the Bohr model explains the coloured lines in hydrogen s emission spectrum. When an excited electron falls from a higher energy level to a lower energy level (shown by the downward-pointing arrows), it emits a photon with a specific wavelength that corresponds to one of the coloured lines in the spectrum. 

Within the simple Bohr model used for weakly bound excitons, the radius of the electron-hole orbit is given by... 

The illustrations that depict the electron configurations of the atoms of each element are based on the Bohr model of quantum energy shells. 

An atom is composed of a nucleus of protons and neutrons surrounded by an electron cloud. Theoretically, electrons may be found at any distance from the nucleus, although they preferentially rotate around low-energy orbits or levels. Within a single level, various sublevels can be distinguished. [The term level corresponds to electron shell in the Bohr model. The terminological analogy is shell K = level I (n = 1) shell L = level II (n = 2) shell M = level III (n = 3) shell N = level IV ( = 4) and so on.] Electron levels are established according to four quantum numbers ... 

An overview of a scientific subject must include at least two parts retrospect (history) and the present status. The present status (in a condensed form) is presented in Chapters 2 to 21. In this section of the overview we outline (sketch) from our subjective point of view the history of electrochemical deposition science. In Section 1.2 we show the relationship of electrochemical deposition to other sciences. In this section we show how the development of electrodeposition science was dependent on the development of physical sciences, especially physics and chemistry in general. It is interesting to note that the electron was discovered in 1897 by J. J. Thomson, and the Rutherford-Bohr model of the atom was formulated in 1911. 

It is instructive to follow the derivation of the London dispersion interaction, for the simplest case of two interacting hydrogen atoms, nsing the Bohr model where the electron is regarded as travelling in well-defined orbits about the nucleus. The orbit of smallest radius, Uq, is the ground state and Bohr calculated that... 

In the Bohr model of the hydrogen atom, an electron travels in a circular orbit about the nucleus at approximately 5 x 10 mlles Per hour How many rev°-lutions per second does the electron make if the radius of the orbit is 2 x 10"9 inches ... 

An estimate of die size of the proton and an understanding of the structure of the hydrogen atom resulted from two major developments in atomic physics the Rudierford scattering experiment (1911) and the Bohr model of die atom (1913). Rutherford showed that the nucleus is vanishingly small compared to the size of an atom. The radius of a proton is on the order of 10-13 centimeter as compared with atomic radii of 10-3 centimeter, Thus, the size of a hydrogen atom is determined by the radius of the electron orbits, but the mass is essentially that of the proton,... 

Tn the Rohr model of the hydrogen atom, the proton is a massive positive point charge about which the electron moves. By placing quantum mechanical conditions upon an otherwise classical planetary motion of the electron, Bohr explained the lines observed in optical spectra as transitions between discrete quantum mechanical energy states. Except for hvperfine splitting, which is a minute decomposition of spectrum lines into a group of closely spaced lines, the proton plays a passive role in the mechanics of the hydrogen atom, It simply provides the attractive central force field for the electron,... 

Quantum Number (Principal). A quantum number that, in the old Bohr model of the atom, determined the energy of an electron in one of the allowed orbits around the nucleus, In the theory of quantum mechanics, the principal quantum number is used most commonly to describe the atomic shell in which tlie elections are located, In a somewhat general way, it is related to the energy of the electronic states of an atom, The symbol for the principal quantum number is n. In x-ray spectral terminology, a -shell is identical to an n = 1 shell, and an L-shell to an n = 2 shell, etc. 

The simple Bohr model of the hydrogen-like atom (one electron only) predicts that the X-ray energy or the transition energy, AE, is given as... 

With the particlelike nature of energy and the wavelike nature of matter now established, let s return to the problem of atomic structure. Several models of atomic structure were proposed in the late nineteenth and early twentieth centuries. A model proposed in 1914 by the Danish physicist Niels Bohr (1885-1962), for example, described the hydrogen atom as a nucleus with an electron circling around it, much as a planet orbits the sun. Furthermore, said Bohr, only certain specific orbits corresponding to certain specific energy levels for the electron are available. The Bohr model was extremely important historically because of its conclusion that electrons have only specific energy levels available to them, but the model fails for atoms with more than one electron. 

In the Bohr model of atomic structure, electrons are constrained to orbit a nucleus at specific distances, given by the equation... 

According to an early theory about the atom, the atom looks like a mini solar system. The nucleus of the atom would be the Sun and the electrons are the orbiting planets. This model of the atom is called the Bohr model. It is named for the Danish physicist, Niels Bohr, who proposed electron shells in 1913. The Bohr model is very useful for understanding how atoms work, but it does not answer some questions about the behavior of all atoms. 

Figure 3.2 In this Bohr model of a nitrogen atom, electrons orbit the nucleus much like planets orbit the Sun. The electrons are located in shells that increase in energy as their distance from the nucleus increases. In a nitrogen atom, there are two electrons in the first shell and five electrons in the second shell.

Students will demonstrate an understanding of the five basic atomic theories—the Dalton atom, the Thomson atom, the Rutherford atom, the Bohr atom, and the Schrodinger electron cloud model—and illustrate this understanding in a two-dimensional work of art. 

The location of electrons in an atom is one factor that determines how that atom will form bonds with other atoms. Scientists use two basic models to explain the location of electrons in the atom—the Bohr model and the quantum mechanics model. 

The Bohr model was developed in 1913 and describes electrons orbiting the nucleus being held in place with energy. In the... 

Bohr model, the energy levels are called orbits. The way electrons move along fixed orbits around the nucleus of an atom is similar to the way the planets orbit the Sun. This is the original, somewhat primitive model for the atom. The Bohr model works well for very simple atoms, but is no longer used in more complex chemistry. 

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