Before Russia's Mendeleev, many people had tried to arrange the periodic table of elements, but none of those tables had ever become widespread.
Mendeleev had loved playing cards since childhood and was rarely seen without a deck in hand. His parents and teachers had been furious about it, believing that a child so obsessed with cards would never amount to much. Mendeleev admitted that he liked playing cards. One day, instead of inviting his card-playing friends over, he shut himself in at home and played alone. But these cards were different from ordinary playing cards—they were made up of elements.
Mendeleev arranged those playing cards day and night. Several days later, one of his colleagues worried that he might have died at home and came to check on him. By then, Mendeleev was not far from madness. He actually told his colleague that he had dreamed of the playing cards dancing.
There were sixty-three known elements at the time, while many more had yet to be discovered. Mendeleev recorded the order in which the cards had appeared in his dream and left a blank card for each undiscovered element. He predicted a total of eleven undiscovered elements. Together with the sixty-three already known, the deck contained seventy-four cards.
No one believed him at first. Only after people successively discovered the eleven elements he had predicted according to his periodic table did they begin to believe what he had said.
Using the periodic law he had discovered, people found another eighteen new elements. Added to the previous seventy-four, there were ninety-two naturally occurring elements in the universe. The elements after uranium, element ninety-two, were not formed naturally; they were all artificial and did not exist in the universe.
Elements one through ninety-two were spread throughout the universe and were not unique