Atoms and Molecules

Trends in Reactivity and the Periodic Table

How was the modern periodic table developed?

A French geologist named Alexandre Béguyer de Chancourtois is actually the first on record to list all of the elements in order of increasing atomic mass. His first version contained sixty-two elements and they were placed in columns that wrapped around a cylinder; however, there were a variety of issues with this first attempt that were later improved upon. Newlands made the next significant advance, publishing the elements in columns of those with similar properties, which brought the description close to the version chemists use today.

The modern version of the periodic table was proposed by a Russian scientist named Dmitri Mendeleev in 1869. His table was the first to lay out the elements in order of increasing atomic mass in columns of elements with similar reactivity. Elements on the table appeared periodically, essentially in accordance with the law of octaves, hence the name “the periodic table.” Mendeleev’s table had to include some blank spaces so that the elements were each in the proper column according to reactivity. As more elements were discovered, the blank spaces in the table were eventually filled in, validating Mendeleev’s table.


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