This book traces the history of development of periodic table and is titled Elementary Order: Mendeleev's Periodic System.Also we see how we have developed a better and deeper understanding of the order in elements after advent of quantum mechanics .The book was translated from Russian by Nicholas Weinstein and was first published by Mir in 1984. Contents How the Elements Were Reduced to Order 7 The Arduous Road Travelled by the Periodic Law 29 The Periodic Law is the Law of Atomic Structure 56 Artificial Elements 102 Foretelling the Future 132 The Omnipresent Law of Periodicity 151