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  2. History of the periodic table - Wikipedia

    en.wikipedia.org/wiki/History_of_the_periodic_table

    This is an accepted version of this page This is the latest accepted revision, reviewed on 28 January 2025. Development of the table of chemical elements The American chemist Glenn T. Seaborg —after whom the element seaborgium is named—standing in front of a periodic table, May 19, 1950 Part of a series on the Periodic table Periodic table forms 18-column 32-column Alternative and extended ...

  3. Periodic table - Wikipedia

    en.wikipedia.org/wiki/Periodic_table

    Periodic table of the chemical elements showing the most or more commonly named sets of elements (in periodic tables), and a traditional dividing line between metals and nonmetals. The f-block actually fits between groups 2 and 3 ; it is usually shown at the foot of the table to save horizontal space.

  4. Periodic trends - Wikipedia

    en.wikipedia.org/wiki/Periodic_trends

    On the other hand, electrophilicity generally increases as electronegativity increases, meaning that electrophilicity follows an increasing trend from left to right on the periodic table. [28] However, the specific molecular or chemical environment of the electrophile also influences electrophilicity.

  5. Alexandre-Émile Béguyer de Chancourtois - Wikipedia

    en.wikipedia.org/wiki/Alexandre-Émile_Béguyer...

    De Chancourtois devised a spiral graph that was arranged on a cylinder, which he called vis tellurique, or telluric helix because tellurium was the element in the middle of the graph. [6] De Chancourtois ordered the elements by increasing atomic weight, with similar elements lined up vertically. [8]

  6. Period 3 element - Wikipedia

    en.wikipedia.org/wiki/Period_3_element

    A period 3 element is one of the chemical elements in the third row (or period) of the periodic table of the chemical elements.The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behavior of the elements as their atomic number increases: a new row is begun when chemical behavior begins to repeat, meaning that elements with similar behavior fall into ...

  7. Aufbau principle - Wikipedia

    en.wikipedia.org/wiki/Aufbau_principle

    The periodic table ignores them and follows idealised configurations. [9] They occur as the result of interelectronic repulsion effects; [7] [8] when atoms are positively ionised, most of the anomalies vanish. [7] The above exceptions are predicted to be the only ones until element 120, where the 8s shell is completed.

  8. Moseley's law - Wikipedia

    en.wikipedia.org/wiki/Moseley's_law

    Moseley's periodic law, concerning the modern periodic table. Auger electron spectroscopy, a similar phenomenon with increased X-ray yield from species of higher atomic number. Discovery of the neutron Mosley's law was an important step in the development of the understanding of the atom.

  9. Period (periodic table) - Wikipedia

    en.wikipedia.org/wiki/Period_(periodic_table)

    A period on the periodic table is a row of chemical elements. All elements in a row have the same number of electron shells. Each next element in a period has one more proton and is less metallic than its predecessor. Arranged this way, elements in the same group (column) have similar chemical and physical properties, reflecting the periodic law.