Anyone who attended a high school science class can probably conjure an image of the periodic table of elements, an imposing array of multicolored rows and columns that sorts all the known chemical elements. This familiar way of displaying the building blocks of the universe is by far the most widespread, but it’s just one of countless possible arrangements. And in their quest for the ideal, chemists have suggested well over 1,000 others.
The version we all know is typically traced to Dmitri Mendeleev, a Russian chemist credited as the chief discoverer of the law that lends the table its name: periodicity. Central to our understanding of chemistry is the fact that certain chemical properties recur regularly, or periodically, as you go along a line of elements. Each of these elements is distinguished from the rest by its atomic number: how many protons reside within one of its atoms. Elements of the same column, or “group,” in the modern table tend to look and behave similarly.
In 1869, when Mendeleev published the first of his many tables, he organized it in such a way that these relationships between elements shone through. The progression is akin to moving upward through the octaves on a piano, where every key bears a resemblance to others at fixed intervals. “Of course, these notes are not identical,” says Eric Scerri, a chemist and philosopher of chemistry at the University of California, Los Angeles. “But anyone with half a musical ear can tell that they are the same note.”
