This book provides an overview of the origins and evolution of the periodic system from its prehistory to the latest synthetic elements and possible future additions. The periodic system of the elements first emerged as a comprehensive classificatory and predictive tool for chemistry during the 1860s. Its subsequent embodiment in various versions has made it one of the most recognizable icons of science. Based primarily on a symposium titled "150 Years of the Periodic Table" and held at the August 2019 national meeting of the American Chemical Society, this book describes the origins of the periodic law, developments that led to its acceptance, chemical families that the system struggled to accommodate, extension of the periodic system to include synthetic elements, and various cultural aspects of the system that were celebrated during the International Year of the Periodic Table.

This book succinctly traces the history of the metric system from early modern proposals of decimal measures, to the birth of the system in Revolutionary France, through its formal international adoption under the supervision of an international General Committee of Weights and Measures (CGPM), to its later expansion into the International System of Units (SI), currently formulated entirely in terms of physical constants. The wide range of human activities that employ weights and measures, from practical commerce to esoteric science, influenced both the development and the diffusion of the metric system. The roles of constants of nature in the formulation of the 18th-century metric system and in the 21st-century reformulation of the SI are described. Finally, the status of the system in the United States, the last major holdout against its everyday use, is also discussed.