Periodic table: scientists propose new way of ordering the elements - The Conversation UK

The periodic table of the elements, principally created by the Russian chemist, Dmitry Mendeleev (1834-1907), celebrated its 150th anniversary last year.

And by the 1860s, it was possible to list the known elements in order of their relative atomic mass – for example, hydrogen was 1 and oxygen 16.

But chemists were aware that certain elements had rather similar chemical properties: for example lithium, sodium and potassium or chlorine, bromine and iodine.

Something seemed to repeat and by placing chemically similar elements next to each other, a two-dimensional table could be constructed.

Importantly, Mendeleev’s periodic table had been derived empirically based on the observed chemical similarities of certain elements.

By the 1940s, most textbooks featured a periodic table similar to ones we see today, as shown in the figure below.

Thus, a periodic table which gives primacy to the electronic structure of atoms will differ from tables for which the principal criteria are certain chemical or physical properties.

These versions don’t differ by much, but there are certain elements – hydrogen for example – which one might place quite differently according to the particular property one wishes to highlight.

Rather more radically, however, we can also consider ordering the elements in a very different way, one which does not involve atomic number or reflect electronic structure – reverting to a one-dimensional list.

If we are to develop replacement materials which avoid the use of certain elements, the insights gained from ordering elements by their MN may prove valuable in that search.

Having many different tables and lists only serves to deepen our understanding of how elements behave