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  2. Electron configuration - Wikipedia

    en.wikipedia.org/wiki/Electron_configuration

    In each term of an electron configuration, n is the positive integer that precedes each orbital letter (helium's electron configuration is 1s 2, therefore n = 1, and the orbital contains two electrons). An atom's nth electron shell can accommodate 2n 2 electrons. For example, the first shell can accommodate two electrons, the second shell eight ...

  3. Aufbau principle - Wikipedia

    en.wikipedia.org/wiki/Aufbau_principle

    The rule then predicts the electron configuration 1s 2 2s 2 2p 6 3s 2 3p 6 3d 9 4s 2, abbreviated [Ar] 3d 9 4s 2 where [Ar] denotes the configuration of argon, the preceding noble gas. However, the measured electron configuration of the copper atom is [Ar] 3d 10 4s 1. By filling the 3d subshell, copper can be in a lower energy state.

  4. Hydrogen atom - Wikipedia

    en.wikipedia.org/wiki/Hydrogen_atom

    The Rydberg constant R M for a hydrogen atom (one electron), R is given by = + /, where is the mass of the atomic nucleus. For hydrogen-1, the quantity /, is about 1/1836 (i.e. the electron-to-proton mass ratio). For deuterium and tritium, the ratios are about 1/3670 and 1/5497 respectively.

  5. Electron configurations of the elements (data page) - Wikipedia

    en.wikipedia.org/wiki/Electron_configurations_of...

    As an approximate rule, electron configurations are given by the Aufbau principle and the Madelung rule. However there are numerous exceptions; for example the lightest exception is chromium, which would be predicted to have the configuration 1s 2 2s 2 2p 6 3s 2 3p 6 3d 4 4s 2 , written as [Ar] 3d 4 4s 2 , but whose actual configuration given ...

  6. 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]

  7. Molecular orbital theory - Wikipedia

    en.wikipedia.org/wiki/Molecular_orbital_theory

    When one electron is removed from an sp 3 orbital, resonance is invoked between four valence bond structures, each of which has a single one-electron bond and three two-electron bonds. Triply degenerate T 2 and A 1 ionized states (CH 4 + ) are produced from different linear combinations of these four structures.

  8. Quantum number - Wikipedia

    en.wikipedia.org/wiki/Quantum_number

    An electron state has spin number s = ⁠ 1 / 2 ⁠, consequently m s will be + ⁠ 1 / 2 ⁠ ("spin up") or - ⁠ 1 / 2 ⁠ "spin down" states. Since electron are fermions they obey the Pauli exclusion principle: each electron state must have different quantum numbers. Therefore, every orbital will be occupied with at most two electrons, one ...

  9. Molecular orbital diagram - Wikipedia

    en.wikipedia.org/wiki/Molecular_orbital_diagram

    In hydrogen fluoride (HF), the hydrogen 1s orbital can mix with fluorine 2p z orbital to form a sigma bond because experimentally the energy of 1s of hydrogen is comparable with 2p of fluorine. The HF electron configuration 1σ 2 2σ 2 3σ 2 1π 4 reflects that the other electrons remain in three lone pairs and that the bond order is 1.