Probing the (empirical) quantum structure embedded in the periodic table with an effective Bohr model

The atomic shell structure can be observed by inspecting the experimental periodic properties of the Periodic Table. The (quantum) shell structure emerges from these properties and in this way quantum mechanics can be explicitly shown considering the (semi-)quantitative periodic properties. These periodic properties can be obtained with a simple effective Bohr model. An effective Bohr model with an effective quantum defect (u) was considered as a probe in order to show the quantum structure embedded in the Periodic Table. u(Z) shows a quasi-smoothed dependence of Z, i.e., u(Z) ≈ Z2/5 - 1.

O centenário da Teoria de Bohr

The year 2013 marks the centennial of that wondrous year in which Niels Bohr proposed a novel theory about the constitution of atoms and small molecules after which the way we regard atoms and their behaviour began to be drastically altered. Bohr drew on several sources for his original description of the atoms, most importantly on spectroscopy and Balmer's equation thereof, the new quantum hypothesis advanced a few years earlier by Planck, and the planetary atom proposed by Rutherford. Although Bohr's ideas were to be eventually overtaken by the advent of quantum mechanics, his theory was the basis of a new thinking about atoms and molecules which constitutes an invaluable asset in the development of science ever since.

O centenário da molécula de Bohr

A hundred years ago, a twenty-eight year old Danish scientist published a series of three papers in which electron motion was quantized. The Bohr atomic model is surely known by every chemistry student. Nevertheless in this same 1913 trilogy, Bohr studied atoms with several electrons as well as molecules. Chemistry students, in general, are not aware of the Bohr molecule. The present paper aims at rescuing this important classical model. A review of the Bohr atomic model for both one and several electrons is discussed, together with a theoretical presentation of the Bohr molecule.

Bohr: O arquiteto do átomo

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

O modelo atômico de Bohr e as abordagens para seu ensino na escola média

The teaching of modern and contemporary Physics subjects in high school is indispensable and it was already justified by several researchers. Among the subjects which must be taught, there is, for instance, Bohr atomics model. However, as it was noticed in literature review, many didactic materials do not deal with this model adequately, since that they do not take into account Bohr ideas, which involved Planck studies on black-body radiation, Einsten theory for photoelectric effect, Rutherford experiences and atomics model and the empiric results upon the spectrums of chemical elements emission. From that, it is extremely important teaching through approaches which potentialize the learning of the model proposed by Niels Bohr. On the other hand, teachers from high schools cannot have clearness about which approaches can be applied for teaching the mentioned model. Thus, it is presented some possibilities for teaching Bohr atomics model, with examples and justifications for the use of each one. Special treatment was attributed to the teaching from Science History and Philosophy, from the reading of scientific diffusion and original scientific texts, from analogies, from comic strips and from computer simulations.

The Hydrogen Atom: The Bohr Model in Detail

The Bohr Model for the Hydrogen Atom's electron is discussed in detail, with a recapitulation of angular momentum and a detailed discussion of relevant units (out of the cgs system).

The Kepler Problem (the road to Bohr)

The classical Kepler problem is reviewed in depth in preparation to studying the Bohr model of the atom.

Laerebog i matematisk analyse af Harald Bohr og Johannes Mollerup.

Mode of access: Internet.

Participants, 1933 Summer Symposia on Theoretical Physics standing outside (incl. Enrico Fermi, Niels Bohr, & Ralph A. Sawyer)

2 scans - 1of2 = photo, 2of2 = key to individuals pictured

Two-dimensional supersonic nonlinear Schrodinger flow past an extended obstacle

Supersonic flow of a superfluid past a slender impenetrable macroscopic obstacle is studied in the framework of the two-dimensional (2D) defocusing nonlinear Schroumldinger (NLS) equation. This problem is of fundamental importance as a dispersive analog of the corresponding classical gas-dynamics problem. Assuming the oncoming flow speed is sufficiently high, we asymptotically reduce the original boundary-value problem for a steady flow past a slender body to the one-dimensional dispersive piston problem described by the nonstationary NLS equation, in which the role of time is played by the stretched x coordinate and the piston motion curve is defined by the spatial body profile. Two steady oblique spatial dispersive shock waves (DSWs) spreading from the pointed ends of the body are generated in both half planes. These are described analytically by constructing appropriate exact solutions of the Whitham modulation equations for the front DSW and by using a generalized Bohr-Sommerfeld quantization rule for the oblique dark soliton fan in the rear DSW. We propose an extension of the traditional modulation description of DSWs to include the linear ""ship-wave"" pattern forming outside the nonlinear modulation region of the front DSW. Our analytic results are supported by direct 2D unsteady numerical simulations and are relevant to recent experiments on Bose-Einstein condensates freely expanding past obstacles.

Mn-doped cubic BN as an atomiclike memory device: A density functional study

We investigate the electronic properties of Mn(B) substitutional doping in cubic boron nitride (BN), for different charge states, using density functional theory (DFT) calculations. We show that the neutral Mn has a nonmagnetic ground state (S=0). Upon charge injection, it is unambiguously shown that the Mn(B)(-) has a high-spin configuration with a strong, localized magnetic moment of 5 mu(Bohr). We developed a simple model, parameterized by the DFT results, that allows us to interpret the rules played by the crystal-field and exchange-correlation splitting in the magnetization process.

The Tausk controversy on the foundations of quantum mechanics: Physics, philosophy, and politics

In 1966 the Brazilian physicist Klaus Tausk (b. 1927) circulated a preprint from the International Centre for Theoretical Physics in Trieste, Italy, criticizing Adriana Daneri, Angelo Loinger, and Giovanni Maria Prosperi`s theory of 1962 on the measurement problem in quantum mechanics. A heated controversy ensued between two opposing camps within the orthodox interpretation of quantum theory, represented by Leon Rosenfeld and Eugene P. Wigner. The controversy went well beyond the strictly scientific issues, however, reflecting philosophical and political commitments within the context of the Cold War, the relationship between science in developed and Third World countries, the importance of social skills, and personal idiosyncrasies.