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  2. Bohr model - Wikipedia

    en.wikipedia.org/wiki/Bohr_model

    The Bohr model of the hydrogen atom (Z = 1) or a hydrogen-like ion (Z > 1), where the negatively charged electron confined to an atomic shell encircles a small, positively charged atomic nucleus and where an electron jumps between orbits, is accompanied by an emitted or absorbed amount of electromagnetic energy (hν). [1]

  3. Potassium - Wikipedia

    en.wikipedia.org/wiki/Potassium

    Potassium is a chemical element; it has symbol K (from Neo-Latin kalium) and atomic number 19. It is a silvery white metal that is soft enough to easily cut with a knife. [9] Potassium metal reacts rapidly with atmospheric oxygen to form flaky white potassium peroxide in only seconds of exposure.

  4. Niels Bohr - Wikipedia

    en.wikipedia.org/wiki/Niels_Bohr

    The Bohr model of the hydrogen atom. A negatively charged electron, confined to an atomic orbital, orbits a small, positively charged nucleus; a quantum jump between orbits is accompanied by an emitted or absorbed amount of electromagnetic radiation. The evolution of atomic models in the 20th century: Thomson, Rutherford, Bohr, Heisenberg ...

  5. History of spectroscopy - Wikipedia

    en.wikipedia.org/wiki/History_of_spectroscopy

    Bohr had been working on his atom during this period, but Bohr's model had only a single ground state and no spectra until he incorporated the Nicholson model and referenced the Nicholson papers in his model of the atom. [56] [57] [58] In 1913, Bohr [59] formulated his quantum mechanical model of atom. This stimulated empirical term analysis.

  6. 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.

  7. History of quantum mechanics - Wikipedia

    en.wikipedia.org/wiki/History_of_quantum_mechanics

    The model's key success lay in explaining the Rydberg formula for the spectral emission lines of atomic hydrogen by using the transitions of electrons between orbits. [24]: 276 While the Rydberg formula had been known experimentally, it did not gain a theoretical underpinning until the Bohr model was introduced. Not only did the Bohr model ...

  8. Timeline of physical chemistry - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_physical_chemistry

    Employing a voltaic pile of approximately 250 cells, or couples, decomposed potash and soda, showing that these substances were respectively the oxides of potassium and sodium, which metals previously had been unknown. These experiments were the beginning of electrochemistry. 1807: John Dalton: Published his Atomic Theory of Matter. 1807: Sir ...

  9. Hydrogen atom - Wikipedia

    en.wikipedia.org/wiki/Hydrogen_atom

    A hydrogen atom is an atom of the chemical element hydrogen. The electrically neutral hydrogen atom contains a single positively charged proton in the nucleus, and a single negatively charged electron bound to the nucleus by the Coulomb force. Atomic hydrogen constitutes about 75% of the baryonic mass of the universe. [1]