Bohrs model of the atom

Footnote The Wave Nature of the Electron. So far the electron has been considered as a particle, with clearly quantised energy levels, that can be precisely measured, as in the emission lines of the spectrum of hydrogen. Because the electron is so small and light, the accuracy with which it can be measured is very uncertain. This is associated with the Heisenberg Uncertainty Principle, which states that it is impossible to determine both the position and momentum of an electron simultaneously , i.e. Ax Ap = hl2it, where Ax is the uncertainty in measuring the position of the electron and Ap is the uncertainty in measuring the momentum (p = mass X velocity) of the electron. The two uncertainties bear an inverse relationship to each other. Consequently, if the position of the 

The allowed values of these quantum numbers are then  

Shell n /- Values Orbital types Capacity Total 

Thus while the Bohr theory provides evidence for the principal quantum number, n, shell structure of the atom, the photoelectronic spectra provide the evidence for the azimuthal, /, and the magnetic, m, quantum numbers. The evidence for the two spin quantum numbers + was obtained by subjecting a beam of silver atoms (Ag) to a non-homogene-ous magnetic field, which divided the silver atoms into two types, according to the spin angular momentum, + of the outer 5s configuration of the Ag atom. 

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As a final note, closer inspection of the emission lines from Na shows that most emission lines are not, in fact, single lines, but are closely spaced doublets or triplets - for example, the strong yellow line discussed above at 589.3 nm is composed of two separate lines at 589.0 and 589.6 nm. This is termed fine structure, and is not predictable from the Bohr model of the atom. It is addressed in the Bohr-Sommerfield model, and is the result of a quantum mechanical interaction, known as spin-orbit coupling, further discussion of which is not necessary for this volume. 

Which of the following did the Bohr model of the atom help explain ... 

The Bohr model of the atom took shape in 1913. Niels Bohr (1885-1962), a Danish physicist, started with the classic Rutherford model and applied a new theory of quantum mechanics to develop a new model that is still in use, but with many enhancements. His assumptions are based on several aspects of quantum theory. One assumption is that light is emitted in tiny bunches (packets) of energy call photons (quanta of light energy). 

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. 

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 principal quantum number n may have positive integer values (1, 2, 3,. ..). n is a measure of the distance of an orbital from the nucleus, and orbitals with the same value of n are said to be in the same shell. This is analogous to the Bohr model of the atom. Each shell may contain up to 2n2 electrons. 

Just as the Rutherford model of the atom developed in 1911 was scientifically startling with its revelation of the atom as mostly empty space, so was the Bohr model of the atom introduced in 1913 with its definition of the location of the electron within the atom. As Bohr and others realized that the atomic spectrum of each element is caused by electrons changing energy levels, a different picture of the atom emerged. The new picture of the atom had electrons at various energy levels within the empty space of Rutherford s model (Figure 8.6). This space can still be said to be empty because the mass of the electrons is extraordinarily small in comparison with that of the whole atom. 

E In the Bohr model of the atom an electron may orbit the atom s nucleus only at certain radii corresponding to certain energies. He called this the quantum theory of the atom. 

Because hydrogen has more than two energy levels, it actually emits electromagnetic radiation at more than one frequency. Bohr s formulation accounted for all of hydrogen s observed emissions. Bohr published his new atomic structure in 1913. According to Albert Einstein, the Bohr model of the atom was one of the greatest discoveries. ... 

Initially they tried to calculate the value of n from the Bohr model of the atom and then from the Lewis-Langmuir model. However the inapplicability of these models was soon realized and the value of n was determined empirically from the compressibility. 

BohrPT Bohr Model of the Atom - Four Quantum Numbers -Electron Configuration of the Atom - Electron Shells - Shapes of Orbitals - Wave Nature of the Electron - Wave Functions, Radial and... 

The electrons are negatively charged particles. The mass of an electron is about 2000 times smaller than that of an proton or neutron at 0.00055 amu. Electrons circle so fast that it cannot be determined where electrons are at any point in time, rather, we talk about the probability of finding an electron at a point in space relative to a nucleus at any point in time. The image depicts the old Bohr model of the atom, in which the electrons inhabit discrete "orbitals" around the nucleus much like planets orbit the sun. This model is outdated. Current models of the atomic structure hold that electrons occupy fuzzy clouds around the nucleus of specific shapes, some spherical, some dumbbell shaped, some with even more complex shapes. Even though the simpler Bohr model of atomic structure has been superseded, we still refer to these electron clouds as "orbitals". The number of electrons and the nature of the orbitals they occupy basically determines the chemical properties and reactivity of all atoms and molecules. 

The initial enthusiasm for the Bohr model of the atom began to fade soon after its introduction. New discoveries in modern physics indicated that Bohr s ideas needed to be modified. The Bohr model of the hydrogen atom pinpointed both the electron s energy and its distance from the nucleus at exactly the same time. However, the Uncertainty Principle of Heisenberg required that if the energy of the electron is known exactly there must be uncertainty concerning its location. Both could not be known exactly at the same time. 

This terminology is derived from the Bohr model of the atom, which was used in early descriptions of the alkali model, most notably by White [26]. 

For a one-electron system, the Bohr model of the atom (which, despite its shortcomings, gives the correct value for the ionization energy) leads to the velocity of the electron being expressed by the equation ... 

Despite its success in reproducing the hydrogen atom spectrum, the Bohr model of the atom rapidly encountered difiiculties. Advances in the resolution obtained in spectroscopic experiments had shown that the spectral features of the hydrogen atom are actually composed of several closely spaced lines these are not accounted for by quantum jumps between Bohr s allowed orbits. However, by modifying the Bohr model to... 

FIGURE 320. Variations of the Bohr model of the atom that was really much more subversive than it looks If an electron is forbidden to exist between orbits, how does it pass from one orbit to the next (from Born see Figure 309) ... 

Characterize the Bohr model of the atom. In the Bohr model, what do we mean when we say something is quantized How does the Bohr model of the hydrogen atom explain the hydrogen emission spectrum Why is the Bohr model fundamentally incorrect ... 

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