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  2. Bohr–Sommerfeld model - Wikipedia

    en.wikipedia.org/wiki/Bohr–Sommerfeld_model

    The whole theory did not extend to non-integrable motions, which meant that many systems could not be treated even in principle. In the end, the model was replaced by the modern quantum-mechanical treatment of the hydrogen atom, which was first given by Wolfgang Pauli in 1925, using Heisenberg's matrix mechanics.

  3. Geometric design of roads - Wikipedia

    en.wikipedia.org/wiki/Geometric_design_of_roads

    Sag vertical curves are those that have a tangent slope at the end of the curve that is higher than that of the beginning of the curve. When driving on a road, a sag curve would appear as a valley, with the vehicle first going downhill before reaching the bottom of the curve and continuing uphill or level. Crest vertical curves are those that ...

  4. Bohr model - Wikipedia

    en.wikipedia.org/wiki/Bohr_model

    The Bohr model is a relatively primitive model of the hydrogen atom, compared to the valence shell model. As a theory, it can be derived as a first-order approximation of the hydrogen atom using the broader and much more accurate quantum mechanics and thus may be considered to be an obsolete scientific theory .

  5. Mathematical formulation of the Standard Model - Wikipedia

    en.wikipedia.org/wiki/Mathematical_formulation...

    The theory is commonly viewed as describing the fundamental set of particles – the leptons, quarks, gauge bosons and the Higgs boson. The Standard Model is renormalizable and mathematically self-consistent; [1] however, despite having huge and continued successes in providing experimental predictions, it does leave some unexplained phenomena. [2]

  6. Atomic orbital - Wikipedia

    en.wikipedia.org/wiki/Atomic_orbital

    Atomic orbitals are basic building blocks of the atomic orbital model (or electron cloud or wave mechanics model), a modern framework for visualizing submicroscopic behavior of electrons in matter. In this model, the electron cloud of an atom may be seen as being built up (in approximation) in an electron configuration that is a product of ...

  7. History of atomic theory - Wikipedia

    en.wikipedia.org/wiki/History_of_atomic_theory

    The current theoretical model of the atom involves a dense nucleus surrounded by a probabilistic "cloud" of electrons. Atomic theory is the scientific theory that matter is composed of particles called atoms. The definition of the word "atom" has changed over the years in response to scientific discoveries.

  8. Atomic model (mathematical logic) - Wikipedia

    en.wikipedia.org/wiki/Atomic_model_(mathematical...

    In model theory, a subfield of mathematical logic, an atomic model is a model such that the complete type of every tuple is axiomatized by a single formula. Such types are called principal types , and the formulas that axiomatize them are called complete formulas .

  9. Plum pudding model - Wikipedia

    en.wikipedia.org/wiki/Plum_pudding_model

    The plum pudding model was the first scientific model of the atom to describe an internal structure. It was first proposed by J. J. Thomson in 1904 following his discovery of the electron in 1897, and was rendered obsolete by Ernest Rutherford 's discovery of the atomic nucleus in 1911.