.. _sphx_glr_api_gallery_structure_periodic_table:

The periodic table
------------------

Periodic trends across all 118 elements, the atomic-weight inversions,
and molar masses from chemical formulas.


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    <div class="sphx-glr-thumbcontainer" tooltip="Mendeleev ordered the elements by atomic weight but let chemical behavior overrule the order where the two disagreed. Most famously he placed tellurium (127.6) before iodine (126.9) so that iodine fell with the halogens. Moseley later showed that the true ordering quantity is the atomic number Z. Left: the standard atomic weights of all 118 elements in chemistrykit.periodic_table.PERIODIC_TABLE against Z. The points where weight decreases as Z increases are exactly the &quot;inversions&quot; an atomic-weight ordering gets wrong. Ar/K, Co/Ni and Te/I are the chemically real ones; those past uranium reflect only the convention of listing the longest-lived isotope&#x27;s mass number for elements with no stable isotope. Right: the periodicity itself, Pauling electronegativity rising across each period and collapsing at each alkali metal.">

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  .. image:: /api/gallery/structure/periodic_table/images/thumb/sphx_glr_plot_01_mendeleev_periodic_table_thumb.png
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  :doc:`/api/gallery/structure/periodic_table/plot_01_mendeleev_periodic_table`

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      <div class="sphx-glr-thumbnail-title">Mendeleev's periodic table: periodicity and the atomic-weight inversions</div>
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.. toctree::
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   /api/gallery/structure/periodic_table/plot_01_mendeleev_periodic_table