There he fell in love with Feozva Leshcheva and they were married on April 4, 1862 in the church in St. Petersburg, right next to the building where he worked . (3) After years of work, Mendeleev, with the help of other scientists, began to create the periodic law. Mendeleev was one of the first scientists to allow others to help him. He began to formulate his periodic law and summarized his laws. If you arrange elements by their atomic weight, they will exhibit similar properties. Elements with the same chemical properties have almost the same atomic weight. The arrangement of elements in groups corresponds to their valence electrons. Widely distributed elements have small atomic weights. The size of an element determines the compound body. We should expect the discovery of new elements whose weight will be between 65 and 75. The atomic weight of an element can be modified by knowing its contiguous atoms.