A Tale of Seven Elements

The periodic table, which arranges elements based on chemical behavior and physical properties, is a triumph of science. Yet the first table, developed in the late 1860s, was riddled with gaps created by undiscovered elements.

By the time researchers recognized in 1913 that elements should be arranged by atomic number (the number of protons in their nuclei) rather than by atomic weight, only seven gaps remained in the list of naturally occurring elements. Chapter by chapter and element by element, Scerri, a historian of science, chronicles scientists’ efforts to fill those holes. A bonus chapter covers elements above uranium, created in laboratories.