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  2. 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 ...

  3. Radium - Wikipedia

    en.wikipedia.org/wiki/Radium

    Of these, 221 Ra (half-life 28 s) also occurs as a 237 Np daughter, and 220 Ra and 222 Ra would be produced by the still-unobserved double beta decay of natural radon isotopes. [13] At least 12 nuclear isomers have been reported, the most stable of which is radium-205m with a half-life between 130~230 milliseconds; this is still shorter than ...

  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. 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 ...

  6. Radon - Wikipedia

    en.wikipedia.org/wiki/Radon

    Electron configuration 4f 14 5d 10 6s 2 6p 6: ... (half-life 3.82 days), which is a decay product of 226 Ra, the latter being itself a decay product of 238 U. [41]

  7. Lanthanum - Wikipedia

    en.wikipedia.org/wiki/Lanthanum

    Ra, the daughter of 232 Th, which is a strong gamma emitter. Lanthanum is relatively easy to extract as it has only one neighbouring lanthanide, cerium, which can be removed by making use of its ability to be oxidised to the +4 state; thereafter, lanthanum may be separated out by the historical method of fractional crystallization of La(NO 3) 3 ...

  8. Extended periodic table - Wikipedia

    en.wikipedia.org/wiki/Extended_periodic_table

    The collapse of the 5g orbital itself is delayed until around element 125 (unbipentium or eka-neptunium); the electron configurations of the 119-electron isoelectronic series are expected to be [Og]8s 1 for elements 119 through 122, [Og]6f 1 for elements 123 and 124, and [Og]5g 1 for element 125 onwards. [84]

  9. List of chemical elements - Wikipedia

    en.wikipedia.org/wiki/List_of_chemical_elements

    118 chemical elements have been identified and named officially by IUPAC.A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z).