This exciting volume helps students understand the central ideas of Mendeleyev's periodic law. Mendeleyev's major breakthrough was his arranging of the elements in sequence by atomic weight but recognizing that there were gaps where no elements had yet been discovered. This account of Medeleyev's struggling childhood in Tobolsk, Siberia, teaching in St. Petersburg, writing The Principles of Chemistry, and development of the table and how his idea was challenged by the scientific community will captivate readers and show them what it means to pursue a question significant enough to follow for a lifetime.