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  2. Helium dimer - Wikipedia

    en.wikipedia.org/wiki/Helium_dimer

    The 4 Π g state has a 1σ 2 g 1σ u 2σ g 2π u electronic configuration, its electron affinity E is 0.18±0.03 eV, and its lifetime is 135±15 μsec; only the v=0 vibrational state is responsible for this long-lived state.

  3. 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 ...

  4. Periodic table (electron configurations) - Wikipedia

    en.wikipedia.org/wiki/Periodic_table_(electron...

    Configurations of elements 109 and above are not available. Predictions from reliable sources have been used for these elements. Grayed out electron numbers indicate subshells filled to their maximum. Bracketed noble gas symbols on the left represent inner configurations that are the same in each period. Written out, these are: He, 2, helium : 1s 2

  5. Helium compounds - Wikipedia

    en.wikipedia.org/wiki/Helium_compounds

    The electron affinity is 0.080 eV, which is very close to zero. [2] The helium atom is small with the radius of the outer electron shell at 0.29 Å. [2] Helium is a very hard atom with a Pearson hardness of 12.3 eV. [3] It has the lowest polarizability of any kind of atom, however, very weak van der Waals forces exist between helium and other ...

  6. 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 ...

  7. Helium - Wikipedia

    en.wikipedia.org/wiki/Helium

    Electron configuration: 1s 2: ... For example, the stability and low energy of the electron cloud state in helium accounts for the element's chemical inertness, and ...

  8. List of elements by atomic properties - Wikipedia

    en.wikipedia.org/wiki/List_of_elements_by_atomic...

    This is a list of chemical elements and their atomic properties, ordered by atomic number (Z).. Since valence electrons are not clearly defined for the d-block and f-block elements, there not being a clear point at which further ionisation becomes unprofitable, a purely formal definition as number of electrons in the outermost shell has been used.

  9. Hydrogen-like atom - Wikipedia

    en.wikipedia.org/wiki/Hydrogen-like_atom

    A hydrogen-like atom (or hydrogenic atom) is any atom or ion with a single valence electron.These atoms are isoelectronic with hydrogen.Examples of hydrogen-like atoms include, but are not limited to, hydrogen itself, all alkali metals such as Rb and Cs, singly ionized alkaline earth metals such as Ca + and Sr + and other ions such as He +, Li 2+, and Be 3+ and isotopes of any of the above.