periodic+table

Early attempts at arranging elements began as early as Ancient Greece with Aristotle's //Four Elements// (30 B.C.). Not very many "elements" were known (at least as we know them today).

Antoine Lavoisier (1789) was the first to begin categorizing elements, but his arrangement was limited to metals and nonmetals.



John Dalton drew symbols for the elements:



Johann Dobereiner (1817) further arranged the known elements into triads - groups of three elements having similar chemical and physical properties.

Alexander Chancourtois organized the then 63 known elements according to atomic weights, and was the first to recognize chemical periodicity. He developed the Telluric Helix to arrange the elements.



John Newlands arranged the elements into groups according to their valences (called the Law of Octaves).



The most accurate periodic table to date was created by Dimitri Mendeleev, a Russian chemist who wanted to organize the elements into a chart for his textbook that he was creating at the time.



His was the basis for the modern periodic table of the elements that we use today.

A novel concept of Mendeleev's was the fact that he purposely left some blank spaces in his table, where he hypothesized the existence of new, undiscovered elements. This information was extremely useful towards isolating and identifying these unknowns.

Today, the same concept is applied to the extended periodic table, where new elements' atomic numbers and valences are known but the element has yet to be discovered or created in the lab.



Some alternative arrangements of the periodic table have arisen: