The iron atom in human blood is synthesized in the depths of stars, solid hydrogen is the lightest solid substance, and 3,500 proteins are formed in one cell. 4000 BC In Ancient China, indigo and kermes were used, and in Egypt, copper was used. The Periodic Table has 7 periods, 18 groups and 118 elements, of which, as we know, everything in the world consists. The biographies and characters of chemical elements were described by Ilya Abramovich Leenson - Candidate of Chemical Sciences, senior researcher at the Faculty of Chemistry of Moscow State University, Associate Professor at the Higher College of Chemistry of the Russian Academy of Sciences, author of scientific and popular science articles, books and teaching aids.