https://doi.org/10.15255/KUI.2015.029
Published: Kem. Ind. 65 (11-12) (2016) 625–628
Paper reference number: KUI-29/2015
Paper type: Professional paper / Chemistry in Teaching
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Is the Periodic System of the Elements Really Periodic?

N. Raos

Abstract

The periodic system of the elements is periodic, but its periodicity is far from simplicity, i.e. the properties of the elements and their compounds cannot be reduced to the “algebraic, periodic function of the values of atomic weights of the elements”, as Mendeleev thought. Besides the well-known trends along the columns (groups) of periodic system, there are also secondary trends such as diagonal behaviour (e.g. similarity of Li to Mg, of Be to Al, and of B to Si), similarities between groups (n) and (n + 10), secondary periodicity inside the group, and knight’s move relationship. These complex relationships are reflected in many attempts at an “ideal” periodic table.

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Keywords

chemistry education, PSE, periodic system of elements, electronic configuration